Jump to content
Dziadeczek

Photo Etching - do it yourself

Recommended Posts

Hi,

I am about to embark on an entirely new technology for me - namely brass sheet photo etching and I have no clue how and where to start.

Before I relegate this task to someone alse, I would like to try doing it by myself, at home, with fairly simple methods and acceptable results.

I need a few intricate brass etched parts for my French 74 guns ship model, which I am building in 1: 48 scale, specifically an ornate stern balcony ballusters, quarter galleries ballusters and gunports hinges, and such...

I've  already built a UV lamp, have drawn some artwork and I am wondering, what's next. I have only a vague idea of how the entire process works, but don't know specifically, where I can obtain chemicals, suitable transparencies, etchants and so on, within the territory of the US  (specifically Southern California). I would prefer not to order those from oversees, since these are corrosive, hazardous chemicals and I might have problems with shipment.

Hence, I have a million questions to ask.  Should I start with purchasing a good book, booklet, brochure, which would in simple, concise words explain everything to a beginner, and if so, which book is recommended? Are there any good tutorials?

Or should I first collect necessary ingredients and start experimenting?

I must unfortunately bypass the offer from Micro Mark, since their kit only permits etching very small plates and I have to etch rather bigger details.

 

Any help in this matter will be greatly appreciated.

Regards,

Thomas

Share this post


Link to post
Share on other sites
1 hour ago, Dziadeczek said:

... I have to etch rather bigger details.

Can you say how big, and what thickness material? One side surface etching or all the way through?

Everything is possible.

 

Bruce

Share this post


Link to post
Share on other sites
23 hours ago, bruce d said:

Can you say how big, and what thickness material? One side surface etching or all the way through?

Everything is possible.

 

Bruce

Bruce,

The size of the plate (brass sheet 0,3 mm [0.014 in.] thick) would have to be about 24 x 14 cm [9.5 x 5.5 in.] to accomodate all parts.

Since it has to be etched all the way through and the sheet is rather thick, I think that it would have to be exposed on both sides and etched a bit longer.

This all is a mystery to me, but I will try to do it myself first and see if it works. If not, I will have to look for someone else who knows how to do it.

At this point I am at the stage of gathering all materials and figuring out what to do.

Thanks for asking!  

Thomas

Share this post


Link to post
Share on other sites

For a learning experience, MicroMark offers a "kit" for etching.   I've heard that it's pretty good for learning the basics and getting a feel for etching.

Share this post


Link to post
Share on other sites

Thomas, I have done a bit of this but only for small parts.

A couple of points that I would make:

1.  It is going to take a long time to etch a large sheet of the dimensions you give. You may be better off to etch several smaller sheets as things do not always go to plan and you could more easily repeat smaller sheets.  than having to repeat a large sheet.

2. One of the problems with thick sheets is "undercutting" where the etchant leeks under the image.

3. MicroMark partly deal with this by having an image on either side of the plate but registration might be a problem.  I have not used their system.

4.  What I did was attach a block of polystyrene to the back of the plate so that the plate floated and only the image side was in the etchant.

Hope this helps.

 

John

 

Share this post


Link to post
Share on other sites

Thomas, John has given good advice. To add my two cents' worth, I cannot emphasize enough how important registration is if etching from both sides. Have a go at etching, there are several good YouTube guides and I suggest you find one that you feel suits your capabilities and facilities: some of the jeweler's processes can look very casual and amateurish but the fact is they work for those people.

However, modellers who need through-etching are not well served by YouTube, and the reason is the difficulty of registering artwork produced without professional equipment. It can be done but the smaller the piece the easier (and the greater the chance of success.)

Brian King's book (in the link in earlier post) is useful but the key to success in 2019 is to use the facilities available in 2019. The etching part of the process is within the grasp of any amateur willing to approach the task methodically, but getting the image onto the workpiece is, and always has been, the 'the trick'. Assuming you are going to use a photoreactive etch resist on your workpiece, finding out how your printer performs when given the task of printing mirror-image versions of an image is the first task. The reason is that you will need two images, exact mirror-images of each other, printed on clear sheet to be placed on either side of the workpiece. The image on these sheets must align perfectly, and this is where home printers may let you down. A slight skew or distortion in most printing jobs is invisible and will never matter at all but in this task any difference in the two images will produce an inferior etching. Also, the image toner must be on the surface that is against the etch resist that will be exposed. If it is not then the light will diffuse through the thickness of the sheet and give a false edge, which translates into a soft/poorly defined edge on the developed resist.

Having an expensive printer is no guarantee of this particular characteristic.  This task is not what modern printers were designed to do with great accuracy so it is necessary to test (you may find that the output of the printer is best in one part of the printed page, such as the middle or bottom, and that is where you will have to place the image). It is easy to see why size matters.

There are build logs on the forum that include home etched components. It would be a good idea to study them and see if they match what you want to achieve and are willing to do.

 

HTH

Bruce

 

 

Share this post


Link to post
Share on other sites

Many thanks to you all for good advice!

I too was thinking about getting this Micro Mark kit just for learning expernience - like you said, Mark. I may go this way later on. As far as the video tutorials, and the books, I already searched this options (and learnt a bit, thank you very much). The book mentioned by grsjax doesn't have  very good opinions, is supposedly a bit dated and doesn't deal a lot with the actual etching process, so I might skip it after all. But thanks anyway!

I too agree that I should start with smaller pieces - easier to etch and manage. However the longest piece I have to etch, is about 22 cm [8.75 in.] in length and I'd rather not etch it in sections and solder the pieces together later on, since I don't think it would look perfect.  So I think I have to etch it whole. See the attachment (this drawing I prepared in Photoshop with the resolution of 600 dpi, so I think it should be fine enough. But I am still tweaking it).

Oh, by the way, the light box I made, has both sides equipped with UV light strips (the bottom and the cover), so I can expose both sides of my plate at the same time. What do you think about it? Would it work?

Yes, I know that I have to place the light sensitive transparency the ink side down, towards the brass plate, - somewhere in those tutorials it was emphasized.

I intend to copy the drawings with a good quality laser printer (professional quality machine) onto dedicated laser printer transparencies (and make mirror images of them for two sided exposures) , rather than using regular printer and cheap transparencies. Someone said it makes a big difference in the quality of prints.

 

Later on I will let you know how my experiments went. Keep your fingers crossed, please!    :)
Regards to all,

Thomas

PS: Does anyone know the US source of Positiv 20 in a spray can? (I couldn't find it anywhere within the US).

Or should I rather use a photoresist foil? Which one is better?

artwork08.jpg

Share this post


Link to post
Share on other sites

Thomas,

 I agree entirely with Bruce's comments about registration.  As I said above I have not used the MicroMark system which uses photo resist on both sides of the plate but I did recently try to print some flags by printing one image on the "front side" side and a mirror image on the other side.  I expperienced a real problem with registration. My printer did not even produce the same sized image when it printed a mirror image!  In the end I got close by using four registration marks on an image in photoshop then flipping it in photoshop and making sure that the registration marks lined up in photoshop before printing.

 

Regards,

John

Share this post


Link to post
Share on other sites

I have etched a lot of printed circuit boards and brass photo etch parts - they use the same processes. Here are some thoughts about photo etching.

 

I have used the Micromark system. It works mostly, but really hit or miss. The main problem is the photoresist. I had great difficulty getting uniform development across the work piece, so parts of the sheet would etch correctly and other parts wouldn't etch at all. Even after it is developed a thin invisible film may remain and this slows or prevents etching. Also, the maximum brass work piece size is about 3" x 3".

 

Larger pieces came out OK, but I was never able to get fine line pieces to etch evenly. I wasn't too happy with it.

 

I had no problems getting good alignment for images on both sides, but I have been making my own double sided circuit boards for about 35 years and have that figured out. I place registration targets in three corners of the film for front and back pieces. I tape the back side to a glass window (or back lighted glass sheet) with blue painter's masking tape. Then I place the front film over it, carefully align it, and then tape it on one edge to the back sheet. Then I slip the brass sheet between the two films for exposure.

 

Do not try to print backwards on your printer. First invert the image in Photoshop, your CAD program, or whatever you are using to generate the artwork.

 

I have used several inkjet and laser printers and some just do not print accurate scale. One HP laserjet always printed at 0.976 true size, so I always used a 1.024 scale multiplier. I used my CAD program to produce a 10 inch "ruler" and measured it with an accurate machinists ruler to determine the scale multiplier. Whatever printer you use be sure to open the printer dialog and set the highest quality print possible. This will place more pigment on the film. Print at 300 dpi or better.

 

There are  bunch of rules for metal thickness versus minimum line/spacing width. The thicker the metal the greater the potential for undercutting - etching metal in the interior of the sheet deeper into the piece than at the surface where the resist is. Faster etching helps reduce undercutting. Thicker metal etches more slowly. Use the thinnest metal suitable for the job. Stainless steel etches slower than brass.

 

The last time i checked the rule for minimum etch widths was something like 1.2 times the metal thickness, So for a gap 0.010" wide the maximum metal thickness is 0.0083". Or with 0.010" thick metal the minimum etched gap width is 0.012".

 

Use a good quality brass! Simple cold rolled brass sheet may have irregularities in hardness that causes some parts to etch slower than others. Any slight bends during the rolling process or handling will result in harder spots. Hard spots can happen if the rolling process stops or varies in speed.

 

You need some method of eliminating the etched residue from the metal surface while etching. If you just lay the sheet flat in a dish the etched material will build up over the surface and slow or stop the etching process. I found the Micromark etch tank with a fish tank air bubbler to be pretty good, but it helps to swish the piece around in the etching solution occasionally. You can also remove the piece from the tank, wash it gently under running water (do not wipe) and return it to the etching solution, but be careful to  not wash the photoresist off the metal!

 

The etchant solution is usually ferric chloride - the same as used for making printed circuit boards. CAUTION: you MUST use plastic or ceramic containers for etching. The etchant solution will also etch metal trays!

 

There are two types of photo resist. With one you design your photo masks so the exposed parts will resist etching (the Micromark process works this way). So your artwork will be dark where you want to remove metal (a negative). With the other the exposed parts will be etched so your artwork will be a "positive" with the dark parts being the part that is not etched. You have to match your artwork with the photoresist type.

 

Use a bright UV lamp to expose the resist! This will allow a fast "flash" exposure. Dim lights will require long exposures and this seems to cause fuzzy outlines in the resist that cause unpredictable etch widths.

 

****

 

For me I think I will go with a commercial photo etch shop, at least for anything that has fine line details.

 

Phil

Share this post


Link to post
Share on other sites

There are two main challenges in doing this at home:

 

- getting the masks with sufficient density of the black parts; neither ink-jet printers nor laser-printers do a job good enough for the purpose; you can fiddle a bit with the direction of printing, as the cross-direction usually gives better densities and you can orient your parts accordingly; there are also 'toner-enhancers', used by the PCB fraternity, that intend to fuse the toner into a more uniform layer, but this is still not good enough for most of the intricate etching we do; I think the way to go is to find a commercial reprographer who can print directly from your file to reprographics film.

 

- small frets, say up to credit-card format can be etched to an acceptable standard in a tray, for larger formats you need an uniformely agitated (vetical) tank; the reason is the velocity distribution when you agitate, it is not uniform across the fret, so that some areas are ready, while others are not yet.

 

As a (geo-)chemist with years of experience in a lab environment, I am very hesitant to mess around with large quantities of corrosive chemicals in the home environment. So I restricted myself to the credit-card format with say a maximum of 50 ml solution at any one time. This has also the advantage that I am using fresh solutions for nearly each fret.

Share this post


Link to post
Share on other sites
8 minutes ago, wefalck said:

... the way to go is to find a commercial reprographer who can print directly from your file to reprographics film.

Absolutely. And be sure to order the two front-and-back images to be printed 'emulsion to emulsion'.

It is worth shopping around as prices vary.

 

Share this post


Link to post
Share on other sites
19 hours ago, grsjax said:

Here is a book on the subject aimed at model builders.  Might be a good place to start.

https://www.amazon.com/Photo-Etching-Workshop-Practice/dp/1854862375/ref=sr_1_2?keywords=photo+etching&qid=1559513506&s=books&sr=1-2

I have a book by these same authors – probably the same thing, but under a slightly different title: Photo Etching for Modellers. Dances around the  subject without actually telling you how to photo etch.

 

I have the Micromark set. The hardware might not be useful to your project, but you can experiment with it pretty simply and might be able to make use of the chemicals and photo-resist material, etc.

 

In So. Cal, you should be able to find chemical suppliers very easily and avoid shipping. I found a place in Sacramento, but it was a while back. I assume you'll be using Ferric Chloride for the etchant and Sodium Hydroxide (Lye - nasty stuff) to strip the photo-resist. Those are what are included in the Micromark set. Micromark also sells those chemicals separately.

 

🤞

Share this post


Link to post
Share on other sites

Thomas,

 

Gene Berger is a member of the Hampton Roads Ship Model Society and he does his own photo etch for his award winning scratch built models.  I consider him a master builder.  He is on MSW as gberger.

 

Here is a link to his website that has a presentation on photo etching.  www.geneberger-models.com/photo-etching/

 

He has taught several of our Club members how to make photo etch parts.

Share this post


Link to post
Share on other sites

Many thanks for the extremely useful info I got from you all, since my last entry! Things are slowly clearing up for me, thanks to you!
Dr PR - I printed your reply and will use it for future references. Ryland - this link is exactly what I've been looking for! I will try to contact Gene Berger and ask him if he could possibly etch these details for me (for a fee, of course). But, as I said, I will first give it a try by myself, if I manage to gather all chemicals and other necessary paraphernalia.

I too would prefer to etch smaller plates, but unfortunately I have this one long piece of 22 cm (8,5 in.) that will have to be etched whole. Other pieces are smaller, about 2, 5 in. so perhaps I should try to do them first as a learning experience, before etching that long one, I think?

 

In any case, thanks again!   :)

 

Regards,

 

Thomas

Share this post


Link to post
Share on other sites

It is always fun to experiment, but I have been there and done that and I don't do it anymore. I had the Micromark PE kit and used it for several projects. It works, but is very time-consuming and finicky. About 75% of my attempts were unusable for one reason or another but with lots of work and practice I did use it to make decent parts for maybe 4-6 projects before I gave up.

 

Now I send .DXF files to https://ppdltd.com/ and a week later receive perfectly formed parts.

 

Cheers and good luck, however you decide to make your parts!

Share this post


Link to post
Share on other sites

Hi fellow shipmodelers,

It has been a long while since my previous post - time spent on my attempts to photoetch at home, as well as  other home tasks, eg. staying alive and healthy recently, socially distancing myself, and such, but finally I have some constructive reporting to post now.

I closely followed the online tutorial on photoetching given by Mr. Gene Berger, which was suggested earlier on by one of the members. Many thanks for it to the Gentleman. I also had a very pleasant telephone conversation with Mr. Berger himself, where he gave me some extra tips.

 

Well, after many trials and errors and various changes into the exposure time and the concentrations of my chemicals, yesterday I finally managed to obtain an acceptable plate. It is not perfect, but it is good enough for my model (Boudriot's 74 guns in 1:48).   What I did is, first - I had to change the cheap developer from some generic Sodium Hydroxide I obtained somewhere online, into the one from Micromark, because my generic NaOH simply did not want to develop anything and subsequently my etchant could not etch anything. It turned out  to be a big lie rather than lye .   :-)   Waisted that way lots of time and material!

Also, I managed to pinpoint the best exposure time for my UV lamp I built earlier. It turned out to be about 90 - 120 seconds only! (45 to 60 secs on each side). The UV light in there really takes care of the photoresist quite quickly, as opposed to the ordinary incandescent light or unpredictable sunlight.
The first trial of a partial plate with the above settings - and the first time a modest success! Voila!!!
My second time - this time with the whole plate rather than its part only, turned out to be not so good. I found out, that the chemicals, both the Micromark developer and the etchant (ammonium persulfate - in my case) are rather unstable and quickly degrade, not just after the first process of etching, but even after a few days, being stored in plastic containers (bottles) and they produce unexpected and unacceptable results - partial, blotchy etching in places and overetching elsewhere.

So, yesterday I decided to prepare brand new chemicals and yet another new brass plate and start all over again. I warmed the etchant to 42 deg C and started the whole process after succesfully developing it. After a few minutes I noticed that the temperature of etchant in the tank was rising. Towards the end, when all elements were about etched, the temp was already 65 degrees C! I think that this was due to the size of my plate 4.5 x 10 in. - quite a big area of etching. This must be quite an exotermic reaction!
Anyway, to make the whole thing short - after 30 minutes of etching, the plate was done! See the attachments.
 I enclose two attachments, the first one shows my artwork I prepared on the Photoshop, and the second one - etched elements from yesterday, shows my parts after the etching. I cut them out with small snips and freed them from the rest of my plate and blackened them with Birchwood Casey - the one for brass/copper. Here I loosely placed them in the same manner as they are on my artwork - to compare both.

 

In conclusion, I have to say, that the entire process of photoetching at home is certainly doable, (though quite tricky), however one must prepare oneself for it beforehand. Firstly, obtain or build a suitable UV exposure lamp, get a laminator, get a few plastic containers for developer and water, get a good etching tank with temp control and a bubble agitator and all neccesary chemicals and photoresist.

Very critical to the entire process is to properly prepare the brass plate, to be as close to perfection as possible, shining like a mirror, free from any debris and grease from your fingertips. Use only distilled water for the entire process. And also the process of applying photoresist onto the plate is quite finicky. Observe exact UV exposure time! If you do everything properly, the rest is just patience - exposing your plate in the chemicals and waiting for the results.

I had lots of experience with an old fashioned B/W analog photography from my earlier, young years, but this process, although somewhat similar in principles, is more demanding and unforgiving. You have to be more exact throughout it, for any deviations will result in unexpected and undesireable results.

BrassEtching2.jpg

etched elements.jpg

Share this post


Link to post
Share on other sites

Hi  Dziadeczek, 

 

Thank you for the interesting post.  This is something I am going to try myself in the near future.  Is it possible for you to provide some details on the process and the chemicals you used?  This would make an extremely useful tutorial and I am sure others also would appreciate it?  For example how you transfer the the image to the brass, do you sit the sheet in the batch of chemicals, or hang it or raise it off the bottom with posts etc etc. 

 

Your gingerbread turned out very nicely, clean sharp edges.  What size brass plate did you use for this - 0.3mm?  Also why did you include the ruler/scale - was this to ensure no loss in accuracy when transferring?

 

Stay safe, best regards

 

Pat

Share this post


Link to post
Share on other sites

Hi Pat,

Thanks for your post.

To answer your questions, first of all, the home made photoetching process has a certain learning curve in it, if one has never done it before. There are several variables to tackle and adjust, depending on your chemicals, their concentrations, temperatures, thickness of your brass, your UV light source, and so on. There are no universal numbers, one has to figure them out through his/her trials and errors, because one uses different chemicals and different ligh sources. So, prepare for yourself adequate supplies of materials and arm yourself with plenty of time/patience. For first several trials to determine those variables, use small samples of your brass and chemicals, not to waiste them excessively. For sure, your first trial or two at least, will not turn out perfectly.  So, be patient and try again and again, until you'll arrive at good results. Write down your variables to be used later as your standards.

For most of your questions you'll find the answers in the above mentioned tutorial by Gene Berger, which is here:   http://geneberger-models.com/photo-etching/   Here I will only signal some points to watch.

I was using a rather thick brass plate = 0.01 inch (0,025 mm). For that thickness you'll have to etch it on both sides simultaneously to avoid excessive underetching (etchant creeping under the photoresist foil ruining details).

You have to prepare your artwork as perfectly as possible, using one of the graphic programs, Photoshop, Corel or Gimp, or similar. Make your drawings in large resolution, 900 dpi, if possible. Everything has to be either pitch black or completely transparent, no grey areas whatsoever. Make sure your drawings are in the proper scale (size) - hence you see a ruler in my artwork. After printing both transparencies i checked one final time to make sure details were in correct sizes. After you are done, make a mirror image copy of it - for your transparencies pocket (see further). Then copy it on laser transparencies using a laser copier with settings of biggest contrast and biggest resolution. The more perfect your artwork, the better will be your etched plate.

Once you have both transparencies mirror imaged, you have to create from them a pocket for your brass plate. Tape one transparency to a sheet of glass iluminated from underneath, with its matte side facing you. Tape the second transparency on top of the first, aligning carefully both, but this one with its dull side facing the first transparency. Carefully remove from glass pane both transparencies which are taped together along three edges, to form a pocket.

 

You have to keep in mind that, if you are using a photoresist foil, the process is similar to analog b/w photography (a negative film vs a positive paper principle). Your transparencies have to be in "negative" of what you want to etch. That means, everything you want to be etched away, has to be black and areas to be left intact, have to be transparent. If you are using a photosensitive spray Positive20 (popular in Europe), this has to be in reverse, what'll be etched away has to be transparent and what has to be left intact, must be black. The carefull allignment of both transparencies is critical for a sharp edges of etched plate.

Another critical variable is a super careful and detailed preparation of your brass plate - polishing and wet sanding with several gradations of fine sanpaper, until the surface is sparkling clean and shines like a mirror. Wear rubber gloves to avoid any grease spots from your fingertips. Do a final rinse of your plate with distilled water, which should run off the brass in sheets.

Now, under UV protective light (a yellow bug lightbulb is OK) you'll apply a layer of your photoresist to both surfaces of your plate . This comes in a roll, sort of like a Saran wrap, covered in a black protective plastic foil, to avoid accidental light exposure. Unroll and cut a neccesary length of this foil (under the UV safe yellow light) and carefully remove the inner protective plastic layer from it's inside curled surface. The best is to use a short piece od Scotch tape taped to its corner and peel it off and discard, to expose super thin bluish layer of this photosensitive foil. Carefully place this foil onto your brass, the peeled off surface down, making sure there are no air bubbles trapped in between. Do the same on the other side of your brass.

Place your brass/photoresist sandwich in a laminator and run it at least 2 times, back and forth. Check again for air bubbles - pierce them, if present, with a sharp point of exacto knife or a needle and run your plate through the laminator once again. Insert your plate/photoresist sandwich inside your transparencies pocket and finally, place this brass/photoresist plate in between two sheets of glass (quartz glass is best, obtained for example from an old copier or scanner) and clamp it tightly together. Place everything in your UV exposure lamp source and expose it on both sides for a predetermined time. This will transfer your artwork from the transparencies onto the brass - you should end up with a distinct black hardened outlines of your details on the photoresist attached to your brass. Remove this sandwich from your light source, unclamp both panes of quartz glass and remove the plate from the transparencies' pocket and store it somewhere in darkness until you are ready to etch.

 

Until now, these are the most important steps, demanding great precision and dexterity, good eyes and patience, because you were working under diminished light - a bug yellow light. The end result of your etching will depend on how well you have prepared your plate.

 

The actual process of etching is now just a matter of preparing your chemicals, pouring them into suitable containers, checking temperature of your etchant, removing  second outer protective layers from a photoresist foil and developing your plate + a final etching of it.

 

Everything on the specific chemicals, materials and where to obtain them from, and other details, you'll find in the above mentioned tutorial by Mr. Berger.

 

I used a special etching plastic tank Gene is talking about, where I suspended my plate vertically and etched it hunging there immersed in etchant. This tank will control and maintain the temperature of your etchant (with a built in heater) and will do all necessary agitating with an aquarium style bubbler. You just sit and wait.

 

Thomas

PS: Sorry for my less than perfect English - after 40 years of living in the US, it is still my 2nd language.    :-(

 

PHOTO ETCHING HOME MADE instructions.pdf

Share this post


Link to post
Share on other sites

Hi Thomas, many thanks for your very informative response which is most helpful.  I had no problems with you English at all, so please no need for any apologies.  As a matter of fact it is better than mine perhaps and it is my first language :)

 

I had anticipated a considerable learning curve and a certain amount of wastage in experimenting so thanks for confirming that.  I am still not sure which path/method to take/use,  but l am leaning towards the photo-resist method at the moment.  I will do a bit more reading of Gene's tutorial, and anything else I find on the subject, before deciding on which method to use.  I think, to a large degree, this will be governed by the availability of resources, the chemicals in particular.  The chemicals cannot be posted/mailed here so I will have to develop a method for chemicals and products I can source locally.

 

Many thanks again, I will now have a much deeper read and be in a better position to experiment.

 

regards

 

Pat

Share this post


Link to post
Share on other sites

Thomas, I am glad you have experienced success in your photo etching of your parts.  It is an interesting process and I have been very fortunate to have seen Gene Berger demonstrate how he makes his photo etched parts.  Gene continues to improve his photo etching expertise with each project he completes.  He shows that it can be successfully done in a home workshop.

 

For those that want more information on do it yourself photo etching, check out Gene's photo etch tutorial at this link: http://geneberger-models.com/photo-etching/

Share this post


Link to post
Share on other sites

I found that the only really critical step is making the masks, i.e. achieving a dense enough blackening. While this is not really a problem for people making circuit boards, it is a problem, when you want to push the technology to its physical limits, which is what we need to do in model building, at least for small-scale models. Neither laser-printed nor ink-jet-printed transparencies are really good enough.

 

I also found that etching 0.1 mm brass or nickel-silver is not a problem, even up to 0.25 mm it works reasonably well, thicker sheets are difficult at least in trays. If you have cuvette with a percolator (air bubbling device), you may be able to push it a bit further. However, it is difficult to match the quality of professional foam- or spray-etched parts. One always battles with over- or under-etching in certain areas of the fret.

 

However, I am talking here about exploring the technique in full, with surface-etching and having details as wide as the sheet-metal is thick.

Share this post


Link to post
Share on other sites

Perhaps, Wefalck, you are more experienced in photoetching than me. I was a complete greenhorn in it, starting from point ZERO!

For me, strangely enough, preparing my artwork, and later on copying it onto laser transparencies, wasn't a problem. Just time consuming. The transparencies (my "negatives") turned out quite fine, enough details, sharp borders and nice b/w contrast. I saved them onto a thumb drive and took it to a nearby Kinko, asked them to photocopy them on laser transparencies, using their highest resolution and max. contrast. They turned out quite nice, certainly adequate for my purpose.

Then, I tried to prepare my brass plates, sanding them into madness, sand paper, starting from about 1000 to 3200 grads. Then I didn't know if I shoud rinse the brass with some isopropyl alcohol or another degreaser. Mr. Berger later on told me that he doesnt' use any degreaser, just sandpaper and makes sure that the water runs off from his brass in "sheets" and doesn't "gather up". So, I stopped degreasing it, after having some problems with it. Than, there was a problem with applying a film (photoresist) on my plates, first removing the outer, curled up protective plastic sheet with sticky tape. It turned out that the photoresist, being very thin, was reacting differently, if I cut a piece from the bigger roll with an exacto knife, versus if I cut it with a pair of scissors. If I used an exacto knife, sometimes I had real difficulties separating this protective layer from the emulsion; that layer wasn't separating nicely, was tearing up the emulsion, and so on... Frustration!  But when I used scissors, the separation along the edges was somewhat easier - I don't know why?

Then, I had a problem with applying the piece of photoresist (exposed emulsion side down onto the brass). If I used a clear tap water to rinse the brass after sanding it untill it looked raw and shiny like a baby's behind, I would find that, after laminating the "sandwich", the tap water would be leaving blotchy, milky spots between the metal and the layer of photoresist, even though before the lamination everything looked perfect. These spots would later on make etching difficult and uneven. So, I started using distilled water for rinsing brass after sanding. That helped.

Than, there was a problem with adequate exposure time in my home made UV light box. I had to determine the best time; not too short, because the emulsion would be too soft and the developer would wash away EVERYTHING, or not too long - than the emulsion would harden so much that the developer would not remove completely areas to be etched away later on. My optimal time turned out to be about 90 seconds (45 seconds on each side, while exposing both sides simultaneously). Generally, if you use a specific UV light source (with appropriate UV light lenghts), the exposure time is much shorter, that with using a regular incadescent lightbulb. And the etching process is more even.

Finally, I had to determine proper concentrations of my chemicals. Mr. Berger gave me some tips, but it turned out that I was using a wrong developer. It was supposed to be Sodium Hydroxide. And mine was! I got it inexpensively from somewhere on line. And I was using 20% concentration - 1 part of this lye to 4 parts of water - like in Mr. Berger's tutorial. But my developer wasn't developing anything! I was getting more and more frustrated and started already to think about etching my plate in some kind of professional etching service.

Then I changed my developer into the one from Micro Mark. A major difference! I started getting some results!!!

From that point on, it was just a matter of finetunning the entire process.

So, as you can see, there are multiple variables to determine before you'll start getting acceptable results.

Then, in order to further improve the quality of your etched parts, perhaps one has to perfect further his artwork. I agree with you on this point.

 

Also, one has to remember, that there are many other chemicals and processes used in photoetching, which require yet different variables to perfect it. I just was using Sodium Hydroxide for developer and Ammonium Persulfate for etching, trying not to complicate everything too much.   :-)

 

Best regards,

Thomas

Share this post


Link to post
Share on other sites

Thomas, I got into this from zero myself some 12 years ago, but stopped because of a house-move and other reasons. I had to figure it out the hard way with few suitable tutorials available at that time. On the other hand, I am a sort of chemist, so that side of the process did not challenge me too much and I understand what is happening (or not) and why.

 

I think the key step for your success was to have the transparencies printed by professionals on high-resolution machines. It would be even better to go to a digital reprography company, where they expose repography films in a special camera, rather than melting toner onto the a transparent sheet. The repography process ensures 100% saturation and the resolution is probably an order of magnitude or more higher than even in professional laser-printers.

 

I obtained my materials from a specialist supplier, including brass sheet already covered in photoresist. This takes out some key variables from the process, though cost more in terms of materials. But then the wastage may be less and it saves a lot of time. Still, I wasted a lot of material until I got all the parameters right, from the exposure times, to the concentrations of the solutions used, to the processing times, etc.

 

Currently, I am actually rethinking the process, having acquired a small laser-cutter a few months ago. I will try to cover brass-sheet in black varnish and then burn the varnish away with the laser-cutter. This cuts out the step with preparing the masks. A technical problem to solve for double-sided etching is the poor zeroing behaviour of the cheap laser-cutter, which makes it difficult to achieve a good rapport when loading the second drawing into the cutter after flipping the sheet over.

Share this post


Link to post
Share on other sites

I respect all who wish to make a hobby all in itself of photoetching. Having done some PCBs and etched model parts myself, and having dealt with the nasty chemicals, I decided the better approach was to take the same money and pay a specialist for better parts. I've had good luck with Hauler in the Czech Republic: https://www.etchworks.eu/

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

About us

Modelshipworld - Advancing Ship Modeling through Research

SSL Secured

Your security is important for us so this Website is SSL-Secured

NRG Mailing Address

Nautical Research Guild
237 South Lincoln Street
Westmont IL, 60559-1917

About the NRG

If you enjoy building ship models that are historically accurate as well as beautiful, then The Nautical Research Guild (NRG) is just right for you.

The Guild is a non-profit educational organization whose mission is to “Advance Ship Modeling Through Research”. We provide support to our members in their efforts to raise the quality of their model ships.

The Nautical Research Guild has published our world-renowned quarterly magazine, The Nautical Research Journal, since 1955. The pages of the Journal are full of articles by accomplished ship modelers who show you how they create those exquisite details on their models, and by maritime historians who show you the correct details to build. The Journal is available in both print and digital editions. Go to the NRG web site (www.thenrg.org) to download a complimentary digital copy of the Journal. The NRG also publishes plan sets, books and compilations of back issues of the Journal and the former Ships in Scale and Model Ship Builder magazines.

Our Emblem

Modelshipworld - Advancing Ship Modeling through Research
×
×
  • Create New...