Using an Airbrush for Semi-gloss or Gloss Finish

[BobG]

32 minutes ago, vaddoc said:

My experience is that trying to fill imperfections with primer will not work, I remember spraying layer after layer of thick automotive primer and sanding in between, still the imperfections were visible. Really the surface needs to be prepared before the primer goes on

That's what my experience has been using a filler primer a couple of days ago. I had the hull sanded about as smooth as I could get it before I sprayed it with the filler primer but it did not fill the tiny imperfections very well. I sanded it and sprayed it again and, although there were fewer tiny imperfections, there were still a some after about a total of 6 coats total now. Of course, I'm trying to get the hull glass smooth since I plan to put a semi-gloss clear coat on it after painting it. I think I may try some Vallejo Gray Primer and see how that works. 

[kurtvd19]

When I want a real smooth wood surface I use this auto body filler.  It's meant to cover the scratches from sanding on metal/fiberglass not big dents.  I use an old credit card or the ones we all get in the mail as a spreader.  I force the filler into the surface as thin as possible.  When it's cured I sand it and check as best I can that I have a good smooth surface and then I prime.  Depending how the primer looks I either lightly sand and apply more filler in areas where it's needed and then sand again or if it's good at that point I skip the sanding and then paint.  When the primer doesn't show any defects it's time to paint.

[BobG]

Thanks Kurt. I'll definitely give that filler a try. 

 

If you end up sanding the primer, how fine do you go...320..400...? I was sanding the primer I used up to 600 and it's almost as smooth as plastic. Now I'm wondering if that may be too smooth a surface for airbrushing the paint...??

 

I have 2 fan spray nozzles for my airbrush also: 0.3 mm and 0.5 mm. I was wondering if you find them useful for spraying larger areas like hulls etc?

[kurtvd19]

Using 400 or 600 there is adequate "tooth" for the paint to adhere it might feel smooth to your fingers but microscopically it's plenty rough enough for the paint.  I rarely use anything finer than 320.

A wide pattern is good for larger areas and a fan spray is good.  I have a small detail touch up gun (Model 400) that Badger used to sell - a miniature body shop type gun.  Perfect for a big hull.  Since I quit the r/c boats I use a Badger 350 for large surfaces. 

The wider the pattern you are able to spray the number of passes you need to cover goes way down.

 

[BobG]

Well I tried out my new airbrush for the first time today and it's awesome! 

 

 I had previously sprayed a filler primer on the hull and sanded it a bit. Today, I decided to use my airbrush to spray the hull with Vallejo Gray Surface Primer and it's much, much better than using a rattle can. I started off with my small paint cup with 10 drops of paint in it and quickly found out that I needed to switch to my largest paint cup. I put 30 drops of primer in it and added 3 drops of Vallejo Flow Improver to it and it seemed to work fine for me. 

 

I'll most definitely try out my larger fan nozzle the next time I prime a hull. The small 0.3 mm regular nozzle had too small of a spray pattern and it took a lot of passes to get consistent coverage. 

 

I don't know if I needed the Flow Improver but I had read good things about it. People saying their nozzles don't clog when they use it. So I decided to give it a go.

 

I don't know anything about what pressure to use so I just used the compressor as it came out of the box. It showed about 22 PSI when I was spraying. The video that came with the kit said it is capable of up to 65 PSI. 

 

I also took the airbrush apart and cleaned everything. I know that I need to at least clean the cup and spray cleaning fluid through the airbrush until it is clear but I'm not how sure I need to do the complete cleaning. It was pretty simple to do so I figured it would be a good idea.

 

I may never use a rattle can again!

 

 

[cog]

9 minutes ago, BobG said:

I'll most definitely try out my larger fan nozzle the next time I prime a hull. The small 0.3 mm regular nozzle had too small of a spray pattern and it took a lot of passes to get consistent coverage. 

Keep in mind you'll need to change distance from the object you are spraying as well as altering pressure when you in or decrease needle/nozzle size

 

I don't know anything about what pressure to use so I just used the compressor as it came out of the box. It showed about 22 PSI when I was spraying. The video that came with the kit said it is capable of up to 65 PSI. 

The more you dilute, and want to get closer for very fine spraying, the lower the PSI. In general with a 0.2 nozzle, and standard milky paint, 18 to 20 PSI suffices

 

I also took the airbrush apart and cleaned everything. I know that I need to at least clean the cup and spray cleaning fluid through the airbrush until it is clear but I'm not how sure I need to do the complete cleaning. It was pretty simple to do so I figured it would be a good idea.

Good to get used to it. You can clean the airbrush in between colours just with thinner or cleaner and a q-tip or a brush - I use a paint brush to wipe the cup. If I plan not to use it for a longer period than two days, I take it apart.

 

 

[BobG]

Thanks for the informative reply, Carl. I can tell that I need to practice quite a bit to get more familiar with competently using my airbrush.

[gjdale]

I view cleaning the airbrush much the same way as sharpening a chisel - keep the tool clean/sharp and it will serve you better. Once you get used to stripping down, cleaning and reassembling the airbrush you’ll find it’s not that big a deal and you’ll become very proficient at it - much the same as gaining proficiency (and speed) at sharpening a chisel. If you get lazy about either task, the tool will not perform at it’s best and you’ll end up taking longer over the main task and likely with more re-dos.

[BobG]

The Vallejo Gray Surface Primer went on the hull so smoothly that I barely needed to sand it. I went over very lightly with 400 sandpaper and it is silky smooth. The difference between using an airbrush to apply primer versus a rattle can is like night and day. I'm really excited to learn to use this airbrush better!

 

[Nirvana]

Bob, you have done a fantastic job with airbrushing.
I have only used Vallejo paint so regarding other brands I have no clue how they are in comparison.
However, when I airbrushed Bluenose, which was my first attempt I was surprised of how well the Vallejo covered the area.

I think the pigmentation in that brand is higher than any other. 

When you are to get the waterline in place, which I found was tricky before I realized there is a trick.

The trick is to use a laser levels self-leveling, place tick mark along that line and it should make it easier.

[BobG]

Thanks Per.

 

I'm really impressed with the airbrush. I've only used Vallejo paints too and I like them very much. Thanks also for the tip for marking the waterline

[vaddoc]

Bob, it will be interesting to see how many coats you ll need to cover the grey primer. Hand brushing it took me a dozen or so

 

Regarding marking the waterline, this is the method I used. Advantage that you can just wipe it clean and start over. 

https://modelshipworld.com/topic/18455-another-way-to-mark-the-waterline/?tab=comments#comment-567858

 

[BobG]

Thanks a very creative way for marking the waterline, vaddoc. Thanks for the tip!

[BobG]

I marked off the the white waterline stripe using an Amati waterline marking jig to give me some lines to spay the general area that will be white. The white stripe will be marked again and then masked off before spraying the green and the black.

 

I sprayed the white stripe using a .3 mm fan spray nozzle in order to give me a broader spray pattern but it still took a lot of passes to get good coverage. Upon closer inspection of the hull after it dried, I found some small imperfections that I didn't see before with the primer on the hull. I'm sure they will be magnified with a semi-gloss varnish as a finish coat so now I'm considering filling them and doing some more sanding which means probably priming the hull again. Maybe I can carefully sand them with 600 grit and see if I can carefully eliminate them. One step forward and two steps back....

 

These imperfections are very small and a couple of them are simply from the slight pressure from the pencil when I marked the white stripe. I'm on the fence as to whether I should try and get the hull even smoother and eliminate tiny imperfections like these, there are only a few but, knowing me, I'll probably take the long road and do try and make it better. Hopefully, I won't screw it up if I do.

 

Getting this hull perfectly smooth so it will look good with a semi-gloss finish is not an easy task. It looks gorgeous with the primer on it but the finish paints are showing up the tiniest little imperfections and that bugs me!

 

Should I or shouldn't I work on making it better...that is the question? I'll have to set it aside and think about it a bit...

 

 

[kurtvd19]

Fix it.  If you don't you will look at it sometime in the future - near or far out - and wish you had. 

The voice of experience.

[cog]

Kurt is right Bob. You will be irritated or very annoyed in the future, if you do not correct the problem. Every time you look at that hull ...

[BobG]

Thanks Kurt and Carl. It will bother me for sure and I've already started trying to fix them. 

 

I'm using the the Bondo Glazing and Spot Putty that Kurt recommended previously for small imperfections. I like it so far. I'm just smoothing on a tiny dab with my finger and then letting it dry before sanding it. I has a rather toxic odor so I'm using it outside. I think I should probably spray the primer again after I've finished touching up the hull. 

[BobG]

I filled the all the tiny imperfections I could find and sanded the hull lightly with 400. Then I sprayed it again with Vallejo Gray Primer using a .5 mm fan nozzle. I also added some Vallejo Flow Improver to the paint at the rate of 1 drop per 10 drops of paint. It turned out well and the imperfections are gone!

 

 

[cog]

Bob, well done. If you have tiny scratches you can also use Mr.Surfacer 500 (also available in rattle can)

[BobG]

Thanks, Carl. I'm happy with the way the hull turned out and I appreciate the advice and encouragement.

[cog]

I know Bob, it looks real smooth, hence my remark for future reference

[BobG]

I've been worried about applying a clear coat to the hull but I finally pulled up some courage and did it this morning. 

 

I have 3 Vallejo Varnishes: matte, satin and gloss. I wanted to try and get a semi-gloss finish so I airbrushed some satin and some gloss on a piece of clean, clay pottery that had a similar matte finish on it as the paint I used to paint the hull. I thought the satin sheen was too low and the gloss was too high so I mixed them the two together in a 50/50 mixture and that looked good to me. 

 

I mixed the the satin and gloss varnishes in the cup of my airbrush along with 1 drop of Vallejo thiner to every 3 drops of varnish. I used a .5 mm fan spray nozzle and lowered the air pressure a bit per the advice I got from Joe Volz previously.

 

It turned out ok but I think it could be better. The sheen is good: somewhere between satin and glossy...just what I was hoping for but, when I look closely at it, it looks a bit rough and I can feel some roughness in the texture. I think I had the air pressure a little too high. Overall, it's pretty good and I think a lot of people would be happy with it but I'm now wondering if I should try and get it smoother.

 

It seems like there might be a couple of options. I ordered some Micro Mesh Polishing Pads that come with 9 flexible sanding pads that range from 1500 to 12000 grit and people seem to love them for polishing out hard surfaces from satin to high gloss. I thought this might be something to try. The second option would be to lightly sand the hull and spray it again and the third option would be to leave it alone since it looks pretty good as is. I suppose I could end up making it worse so it might be in my best interest to leave well enough alone!

 

It's been several hours now since I sprayed it and it still has a very slight tackiness feel to it so I'm going to let it sit until I can't feel any tackiness at all before I try anything. I feel like I've got a lot to think about...

 

I hope you can see the semi-gloss sheen in the photos below. The last photo is an extreme close-up that clearly shows the roughness in the texture. It looks awful in that photo but you really don't notice it unless you hold the hull up close and examine it.

 

So what to do now? Is there a proper fix or should I just leave it alone...?

 

 

[Nirvana]

Bob, did you experience the same with the white and black colors?
It's hard to tell in the pictures. 

I have use the soft-pads available from 2000 through 12000 grit with success.
 

37 minutes ago, BobG said:

I hope you can see the semi-gloss sheen in the photos below. The last photo is an extreme close-up that clearly shows the roughness in the texture. It looks awful in that photo but you really don't notice it unless you hold the hull up close and examine it.

 

So what to do now? Is there a proper fix or should I just leave it alone...?

 

The paint job looks good to me, and when viewing it from lets say 2ft and you can't see it - leave it.
I know how we are as perfectionists.... can't leave it until 200% satisfied.

[BobG]

22 minutes ago, Nirvana said:

Bob, did you experience the same with the white and black colors?

Yes, it's here and there in all the colors but the white is the most difficult to see it. 

 

23 minutes ago, Nirvana said:

I have use the soft-pads available from 2000 through 12000 grit with success.

Did you use them on any clear coats? Were you able to get rid of this "orange peel" effect that I'm seeing in the clear coat?

 

25 minutes ago, Nirvana said:

The paint job looks good to me, and when viewing it from lets say 2ft and you can't see it - leave it.
I know how we are as perfectionists.... can't leave it until 200% satisfied.

Thanks, Per.

 

This is the first thing I've ever painted with my new airbrush. I'm pretty sure I must have had the pressure too high. I was going to lower it more but the nozzle clogged almost immediately and I had to empty the paint cup and clean the airbrush. At that point, I decided not to lower the pressure for fear that I might get another clog. I'm at that stage of "live and learn" when it come to airbrushing.

 

My perfectionism can be a pain in the butt at times!

[Nirvana]

Bob,

Yes I have used it on clear coat, just making sure you are using water as well.

 

I am considering buying new compressor with tank, this way you won't have any issues with dropped pressure, the pressure is easier to set and the airflow will be more even.

Also the "paint brush" is very important, there is a reason some of the "brushes" are over 100 dollars. 
Secondly maintenance and cleaning of the brush is very..... very important.

[BobG]

11 minutes ago, Nirvana said:

Yes I have used it on clear coat, just making sure you are using water as well.

I used Vallejo Model Varnish and it is water based. Would wet sanding be a problem on these water based varnishes?

[Nirvana]

That's a real good question, I would suggest to do a test on a separate item not on the ship.

Only a test will tell, unless someone else has the answer.
I used enamel varnish, which may have been an overkill.

[Bob Cleek]

It does appear that the paint was applied too heavily and, hence, the "orange peel" effect, although I've encountered much worse. As has been said, the surface preparation has to be perfect... smooth as the proverbial baby's bottom. Your fingertips are the best measure of this. You can feel the imperfections better than you can see them. I always use a sanding base coat which is made for the purpose of filling minor imperfections and easily sanding to a perfectly smooth surface. Anything more than very minor surface imperfections require filling with "surfacing putty." I generally take down my base coat to 320 or 400 grit. There's not much point in going finer than that before airbrushing.

 

If the entire surface is as in the last picture, I'd say that if you want it to be good, you are going to have to sand the entire hull with 320 and then 400 to get the surface fair to begin with.  Be sure to allow the paint to really dry for a few days so it's good and hard and doesn't gum up your sandpaper. As you will be sanding hard paint instead of sanding base coat, it may be a pain, but take your time and make sure it's really perfectly smooth. Hopefully, you won't sand through the paint surface and won't need to repaint, but if you do, then make sure your paint is thinned well. Several thin coats, allowing time to dry well between each, is the way to go. Try to resist trying to get that last bit of "cover" over a wet surface. Too much wet paint is going to give you that "orange peel" again. You might also consider adding some "flowing" conditioner to the paint. This retards the drying and allows the paint to "level" better. Your paint may require a proprietary "flowing" additive. If it's an acrylic, you might experiment with Flood's "Floetrol." https://www.flood.com/products/paint-additives/floetrol-latex-based-paint-additive

 

After you've sanded the hull fair, you can apply another coat of paint if need be. (Again, build up your paint coating with multiple thin coats. Never apply paint thickly.) I wouldn't waste time messing with proprietary varnishes of varying glosses. They are often tricky to use and get just right. Instead, I'd let the paint dry well and then rub it down to the gloss level you desire using rottenstone and pumice. These provide two degrees of very fine "grit," rottenstone being the larger grit. They are powdered abrasives applied with a water-dampened soft cloth. It will probably take some time rubbing, but you will be able to see the level of gloss as you use them. If you want, you can also speed up the process a bit by using finer grit sandpapers, and then go to the finer rottenstone and pumice abrasive. Continued rubbing with the finer pumice will bring the gloss up as high as you want. You can get pretty close with an airbrush, sometimes even "close enough," but rubbing out the surface is the only way I know to get a perfect finish.

 

Here's a two-part video that shows how to do it on bright-finished wood, but the process is the same for varnished or painted surfaces. You won't need an electric polisher because you've only got a small piece to do and the electric polisher won't do so well on your curved surfaces. (In these videos, he uses fine grit sandpapers instead of the rottenstone and pumice because they work better with a powered sander on flat surfaces. I use rottenstone and pumice on model hulls because the surfaces are curved and a damp cloth abrades more evenly on the curves. Rottenstone and pumice, available at any paint store, are a lot cheaper than fine grit sandpapers, too!) I'd advise you paint up two or three pieces of scrap wood and use these to practice on before attacking your model. It's a process of experimenting to see how much sanding and polishing you really need to do to get to where you want the finish to be.

 

 

 

 

 

[BobG]

Thanks very much for your reply, Bob. Much appreciated.

 

I think you are spot on about what happened. I tried to keep the varnish fairly wet and ended up putting on too heavy a layer. When I painted the hull I used Vallejo Model Air paints and I added some Vallejo Flow Improver to the paint and I was really satisfied with the way the hull turned out. They were all matte colors and I needed to put on a clear coat to get the sheen I wanted.

 

Today, however, I just thinned the Vallejo Varnish and didn't put the Flow Improver into the mix. I sprayed outside in my garage in the morning and it was cool so I didn't think I'd need the Flow Improver since the paint had been thinned. In hindsight, I probably should have added it. That said, I think that the main culprit was that I applied the varnish too thick. Of course, the other culprit, was me being entirely new to this.

 

Oh well, they say we learn the best through our mistakes but, damn, I hate it when that happens...

 

 

[vaddoc]

Bob, I am not sure that the flow improver or the retarder are designed for the varnish. They are to be used with the acrylic paint that is completely different to the varnish.

You should not really have a rough surface after varnish, it should be very smooth. Also, It should not really feel tacky after all this time. I think that either your varnish suspension broke up by using too much thinner (the varnish is not paint, I think you can thin up to 20%) or that the water media evaporated before the varnish touching the hull. The Valejo varnishes have extraordinary self levelling properties. It could also be that these varnishes need water to thin and not the air thinner.

 

These are only some of my thoughts as there are very little info on the Valejo site or anywhere else really.