Jump to content

Recommended Posts

Posted (edited)

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

Edited by Dziadeczek

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
Posted (edited)

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

Edited by Dziadeczek

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

It is safer to mirror-image the drawing in your program and sent them two files. If you have any surface-etched details, you will have two images/files anyway.

Share this post


Link to post
Share on other sites
Posted (edited)
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.

 

🤞

Edited by catopower

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
Posted (edited)

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

Edited by Dziadeczek

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

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...