Using an Airbrush for Semi-gloss or Gloss Finish

[BobG]

I am currently building the Pen Duick by Artesania Latina and will be painting the hull soon with my new airbrush after practicing with it on some scraps. At this point, I plan to use Vallejo Model Air Acrylic Paints for the 3 different colors on the hull. I want to simulate the resin hull of the Pen Duick after it was restored by Eric Tabarly in the late 1950's. The photos I have seen of the yacht at this time show that the sleek hull was highly polished. I am assuming that a semi-gloss would be appropriate or maybe even a gloss finish similar to many of the America's Cup, J-Class racing sailboats. So I have a couple of questions regarding using an airbrush to obtain an appropriate finish like that on the hull.

 

First of all, would a semi-gloss or gloss finish be more authentic and what would what the best way to apply a crystal clear, semi-gloss or gloss finish using my airbrush? Is clear coating with an airbrush any different than normal painting with an airbrush?  Does anyone have experience obtaining this kind of clear, polished finish and, if so, what clear coat products did you use? 

 

Thanks very much.

[jwvolz]

Bob,

 

In scale, semi-gloss would be more appropriate.

 

I've used my airbrush for many years to finish plastic models, and wooden ships as well. Since you are already using Vallejo, I can recommend their varnishes. Just thin them with water to get them to spray properly. In this case I would use the Satin, but you may want to try a blend of some combination of matte/satin/gloss to get the exact gloss level you want. 

 

Keep the pressure low (15 or so PSI) and apply in smooth wet coats. If you get too high with pressure or too far from the model you can end up with a rough finish due to the varnish drying in the air on the way to the model. 

 

Practice on some scrap until you are comfortable. 

 

 

 

[BobG]

Thanks very much, Joe.

 

11 minutes ago, jwvolz said:

In scale, semi-gloss would be more appropriate.

 

I've used my airbrush for many years to finish plastic models, and wooden ships as well. Since you are already using Vallejo, I can recommend their varnishes. Just thin them with water to get them to spray properly. In this case I would use the Satin, but you may want to try a blend of some combination of matte/satin/gloss to get the exact gloss level you want. 

I've been happy with brushing Vallejo Acrylics so I just thought I'd continue with them since I am totally new to airbrushing. I take it that they don't make a semi-gloss varnish so I'll need to experiment as you have suggested.

 

14 minutes ago, jwvolz said:

Keep the pressure low (15 or so PSI) and apply in smooth wet coats. If you get too high with pressure or too far from the model you can end up with a rough finish due to the varnish drying in the air on the way to the model. 

It gets very hot and dry here in Sacramento during the summer. I will be painting outside so it looks like I'll need to spray early in the mornings as well when applying a clear varnish to try prevent the varnish drying in the air. How long do these varnishes generally take to dry before applying additional coats? Are several coats preferred for getting a nice finish with these varnishes?

 

A few more questions:

 

Have you used the Vallejo Model Air Paints other than their varnishes? If so, did you need to thin them very much with water? Is it better to use distilled water than regular tap water? Would the Vallejo Thinner be better to use than water?

 

Much appreciated. 

[kurtvd19]

Bob:

I agree 100% with Joe's advice.

 

There is another alternative.  Plastic modelers have used the household floor finish FUTURE for a gloss coat finish - over all sorts of paints.  They have changed the name several times but Future or Pledge was always someplace on the label.  I had to buy a new bottle and the bottle now says Pledge - Floor Gloss.  The thing I like about the newest product is that it isn't a true gloss coat with only one airbrushed coat.  Semi-gloss with the first coat going to true gloss with additional coats.  Makes it more suitable for my purposes.

 

Applying any clear coat you have to watch how much is applied - I have found that a bit of practice off the model will give you the experience you need to judge how much is enough and how much is too much.

 

 

[cog]

Plastic, wood, metal. It all comes down to the right varnish, and dilution for you. I for instance do not like the airbrush varnishes from Vallejo, I prefer mig or Tamiya, and will try MrColor when it comes in next week. Preparation is another important element. You might want to give this chap's handy work a look:

https://youtu.be/1zAmzmnDJoA

[BobG]

Thanks Kurt and Carl. It looks like I have quite a bit to learn before I actually commit to painting the hull. I really do not want to mess up the paint job on this hull. 

[jwvolz]

14 minutes ago, BobG said:

Thanks very much, Joe.

 

I've been happy with brushing Vallejo Acrylics so I just thought I'd continue with them since I am totally new to airbrushing. I take it that they don't make a semi-gloss varnish so I'll need to experiment as you have suggested. Vallejo makes a satin, which is close to a semi-gloss. 

 

It gets very hot and dry here in Sacramento during the summer. I will be painting outside so it looks like I'll need to spray early in the mornings as well when applying a clear varnish to try prevent the varnish drying in the air. How long do these varnishes generally take to dry before applying additional coats? I generally apply several light coats right on top of each other. With acrylics you can apply mulitiple coats within about a one hour window, or else wait about four hours. Too soon  can cause cracking as the underlying layers are still drying. Are several coats preferred for getting a nice finish with these varnishes? Yes, generally several coats to even gloss levels out. 

 

A few more questions:

 

Have you used the Vallejo Model Air Paints other than their varnishes? Yes, all the time. If so, did you need to thin them very much with water? I never need to thin them for airbrushing.  Is it better to use distilled water than regular tap water? Would the Vallejo Thinner be better to use than water? When I do thin paints for airbrushing I use tap water (mine's not bad) with a few drops of alcohol and Liquitex flow-aid to help to slow it from drying on the tip.

 

Much appreciated. 

 

[jwvolz]

Also... I agree with Kurt about "Future" it's good stuff, it does just have a bit more of a learning curve. The current name is "Pledge Revive It Floor gloss". I get it at Walmart. 

 

I've used it for years as gloss prep coat for decaling plastic models. If you do use it make sure to keep the pressure down, as it's very prone to not laying smoothly at high pressure. Also...it magnifies the paint surface it goes over, so very matte paints end up looking glossy but still feel rough. Rub them down beforehand with a soft cloth to knock off the peaks and valleys of the flat paint. One more point is to make sure the underlying paint is fully dry; at least 48 hours. I've had cracking issues when I've applied too early. 

[BobG]

Thanks, Joe. I'm excited to learn to use my airbrush and the information I'm getting here from experienced modelers will be invaluable to me. This is outstanding information!

[kurtvd19]

5 minutes ago, jwvolz said:

When I do thin paints for airbrushing I use tap water (mine's not bad) with a few drops of alcohol and Liquitex flow-aid to help to slow it from drying on the tip.

 

Joe:

Alcohol speeds up the drying of acrylics and promotes tip dry.  I have seen this promoted many places - but think about it - alcohol evaporates much quicker than water.

 

As to adding tap water - perfectly fine if adding it to the paint for the session only.  But if adding water to the entire jar it is much better to use distilled water for longer storage.

 

I offer the above not in any was as argument but as official policy of Badger Airbrush - who also manufacture the Badger Modelflex Paints as well as other acrylic paints under the Badger name.

 

[jwvolz]

No disagreement there Kurt. The reason I use a tiny bit of alcohol is to break surface tension and help flow. I do agree though, that's why I only use a little. 

 

I never thin in the bottle, just mix directly into airbrush cup for that session. Helps with shelf life and I don't generally want the bottle too thin as it hurts coverage when brush painting. 

[BobG]

Great discussion everyone! 

 

Here's another question from this airbrush newcomer: Is there much difference between Vallejo Model Air Paints and the regular Model Paints? I assume that they may have difference viscosities and, if that's the case, it would stand to reason that the Vallejo Model Air Paints are thinner right out of the bottle and the regular Model Paints will need to be thinned before usage?  

[jwvolz]

Bob,

 

Yes, big difference in viscosity right out of the bottle. The regular are very thick and I find them a pain to adjust to airbrush viscosity. I use the "air" for everything including brush painting. I find the thinner paint leaves fewer brush streaks, and that way I'm also not doubling up on colors. 

 

I'm a big fan of the Model Air line. 

[kurtvd19]

I use Badger paints exclusively - they are airbrush ready.

Almost all "model" paints are air brushable - some with thinning some as they come.  The pigment of model paints is ground very fine - a necessity so details are not hidden by thick paint.  Don't even consider going to the hardware store and then thinning the house paint or other paint they sell.  Most advertise "Cover in One Coat!" which means the pigments are very coarsely ground in order to cover in one coat.  Thinning doesn't change the size of the pigment - just the viscosity.  Model paints usually have very small pigment sizes in the order of one micron where the house paints usually have a pigment size on average of 37 microns.  I can tell you that my fine detail airbrushes will instantly clog if I were to load one up with this stuff.

 

Stick with a model paint that works for you.  Try to stick with one brand so you are not constantly trying to make the new stuff work.  Once you are experienced feel free to experiment (NEVER on the model itself) but maybe there is a new paint that will work better for you at some point.

[DelF]

I’m grateful to Bob for raising this topic. 
 

Being new to airbrushing myself I’m finding this discussion very interesting and valuable. There certainly seems to be a steep learning curve for beginners, but my experience so far (less than a week!) is that the results you can achieve make the effort well worthwhile. One bonus for me is that I’ve found I can airbrush shellac - my preferred finish for bare wood. 
 

Derek

[BobG]

10 minutes ago, DelF said:

There certainly seems to be a steep learning curve for beginners, but my experience so far (less than a week!) is that the results you can achieve make the effort well worthwhile.

That's great to hear, Derek! I'll be trying out my new airbrush in the next couple of days and I'm excited. 

[vaddoc]

7 hours ago, BobG said:

Is there much difference between Vallejo Model Air Paints and the regular Model Paints?

Just to add regarding the Valejo, that the thinner for air brushing and for hand brushing are very different and not really interchangeable.

 

For hand brushing, it is important to use the proper thinner to get good results, I did not have good results using the air thinner that comes in a very big bottle or water. However, using the hand thinner with a bid of retarder and thinning the quite thick paint to a milky consistency, painting is a dream with no brush marks at all. This is why I do not have an airbrush despite the large scale I work at. 

[BobG]

I have a couple more questions that have come to mind:

 

1) Is it best to apply a good primer before painting with an airbrush? If so, are common rattle can primers acceptable or are specific model paint primers better?

 

2) Is it a wise to wear a mask for lung protection when using an airbrush? 

[gjdale]

If you are using an airbrush Bob, why not use it for the primer as well? If you are using Vallejo paints, their primers are also very good. I have found that thinning them 3 parts paint to 1 part (Vallejo) thinner works pretty well.

 

Although acrylic paints don’t have the “nasties” in them, they are still atomising the paint, so lung protection is always a good call.

[kurtvd19]

21 hours ago, BobG said:

1) Is it best to apply a good primer before painting with an airbrush? If so, are common rattle can primers acceptable or are specific model paint primers better?

I didn't always use a primer because I use Badger Modelflex paints and primer isn't required for them.  I am starting to use primer more now that Badger developed a new primer called Stynylrez - for use over Styrene, Nylon and Resins.  They started with gray, black and white but after it was released demand made them provide it in more colors as many are using it as a final coat when doing figures and sci-fi.  They now provide it in 18 colors and I have used it as the final color coat on a couple of models myself.

However, I always use a primer when I am painting over a model with any filler added or when different materials are used (not 100% wood or 100% plastic) to hide the different colors that will make the paint look a bit different over each underlying material.

I also always use a primer when painting certain colors like yellow that don't cover well w/o many coats.

As to using rattle cans - it depends on the size of the model.  If it is large enough to be able to do a light sanding of the entire model then rattle can applied primer is fine.  If I can't easily sand it because of size or nooks and crannies I don't use the rattle can.  Or I decant the rattle can paint and use it in an airbrush.

 

In the last couple of years I have switched to using Stynylrez primer on all work I do.

 

21 hours ago, BobG said:

2) Is it a wise to wear a mask for lung protection when using an airbrush? 

If you are not using a spray booth I would recommend a particulate filter mask - the fumes of acrylics are not particularly harmful but all sprayed paint has particles you don't want to breathe in.  Using a good spray booth makes a mask unnecessary - at least in my opinion.  The fumes and particles are sucked into the filters of the spray booth.  Using acrylics a good filter on the end of the fan outlet is sufficient unless you are in a very small area and should then direct the booth's output to the exterior.  Absolutely do that if using solvent based paints.

[BobG]

Thank you Kurt and Grant for the great information. I'm excited to start trying out my new airbrush!

[BobG]

How finely should the primer be sanded before you paint it with an airbrush... 220 grit, 320, 400, 600...?? I would assume dry sanding only...not wet sanding??

[gjdale]

If you’ve used a modelling type primer (eg Vallejo), I wouldn’t be sanding at all before applying main paint. When you use it, you’ll see just show smooth a surface it provides.

[BobG]

Primers always show up tiny imperfections that I can't see before applying the primer. Doesn't the same thing happen when you use a modeling type primer and wouldn't you then need to sand out those imperfections and, perhaps, reapply the primer?

[gjdale]

I was assuming you'd already done that bit Bob. Once you've got a nice smooth surface, then the primer doesn't need further sanding.

[Bob Cleek]

9 hours ago, BobG said:

How finely should the primer be sanded before you paint it with an airbrush... 220 grit, 320, 400, 600...?? I would assume dry sanding only...not wet sanding??

It depends upon how thick the primer will be applied. It should be applied very thinly on a model, so I'd say 320 would be as coarse as you dare. 400 would be better. 600 is probably finer than you need it.

 

Wet or dry, doesn't matter. Dry is a lot less messy.

 

It has to be perfectly smooth. Use your finger tips to feel for imperfections. Touch is better than sight.

[Bob Cleek]

10 hours ago, BobG said:

How finely should the primer be sanded before you paint it with an airbrush... 220 grit, 320, 400, 600...?? I would assume dry sanding only...not wet sanding??

It depends upon how thick the primer will be applied. It should be applied very thinly on a model, so I'd say 320 would be as coarse as you dare. 400 would be better. 600 is probably finer than you need it.

 

Wet or dry, doesn't matter. Dry is a lot less messy.

 

It has to be perfectly smooth. Use your finger tips to feel for imperfections. Touch is better than sight.

[DelF]

For me, one of the benefits of airbrushing is that it lays such a thin coat of paint that it doesn't mask details, especially on small, fine parts. Using primer, I'd be worried that I'd lose some of that detail.

 

I've only used primer once in the (very!) short time I've been airbrushing. I didn't find I needed it on photo etched parts provided they were properly prepared, either by chemical etching or light rubbing with a very fine sanding stick or steel wool. I didn't use it on Speedy's swivel guns either, where the airbrush covered the plastic barrels and brass mounts very well.  As for wood, I tend to use sanding sealer which gives a very smooth finish for hand brushing and seemed to work equally well for airbrushing when I painted the channels. The only time I used primer was on Speedy's anchors which were bright white metal, which I felt might need a base coat. But I wasn't so concerned about detail in that instance. 

 

The common feature in all these cases where I didn't use primer is that they all involved small components that wouldn't be subject to much handling after painting. I imagine it would be very different if you were dealing with a whole ship's hull, for example.

 

Obviously there are vastly more experienced people on the forum who can give much more information than I can. I just wanted to report my early experience which is that primer is not necessary in every situation.

 

Derek 

[BobG]

7 hours ago, DelF said:

For me, one of the benefits of airbrushing is that it lays such a thin coat of paint that it doesn't mask details, especially on small, fine parts. Using primer, I'd be worried that I'd lose some of that detail.

That's a good point about the benefit of airbrushing in retaining fine details. I think that the primers that are made specifically for modeling and can be applied with an airbrush are thinner than the typical rattle can primers so they would not obscure details as much.

 

I'm using a rattle can of Rustoleum High Build Gray Primer on the hull of the Pen Duick that I'm currently building. I had sanded the hull and had filled any imperfections that I could see with Elmer's Wood Filler before I sprayed it with the rattle can primer. I was not interested in preserving any details though. I chose the high build type primer because I wanted it to fill the tiniest of imperfections. My plan has been to prime and sand the hull until it is as perfect as I can get it since I know that the semi-gloss clear coat I will apply over the acrylic paint will magnify any imperfections.

 

I'm not sure that it was the best choice to use a high build type primer. It may have been overkill. We'll see...

[vaddoc]

I always seal the wood before painting, it leaves a very smooth surface, I do not like to paint raw wood. I often use primer, to improve adhesion but mainly to have a uniform colour as a base and reduce the number of coats of paint needed

I ve used automotive primers in the past and they are not very good for modelling. They spray very thick, take a long time to cure and are smelly. For a long time now I ve been using Humbrol primers that come in red, white and grey, the latter I find is the most useful. They are expensive but very nice-no nasty smells. It leaves the surface smooth but a quick pass with 400 grit could be done.

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