Greetings all. For my first ever post on Armorama, I'm looking for some troubleshooting assistance. I've been having a real problem airbrushing various brands of acrylic clear flat coats. The main problem is that no matter what formulas, brands, thinning ratios or ritual dances to the modeling gods I use, I always end up with a finish that makes the model look dusty. No outright frosting, like you get if you spray Tamiya Flat Base straight, but varying degrees of a dusty layer that looks more like weathering than a clear coat. My goal is to get as dead flat finish as possible. A slight sheen isn't too bad, but would prefer not to have any...especially on figures.

After spending too many evenings experimenting and spraying, I'm throwing my arms up in frustration and looking for some input on what I might be doing wrong.

Late last year I returned to modeling after an eight year hiatus. Back in the day, I used Polly-S clear flat and I loved it. I went on dead flat without thinning and it never frosted or turned dusty on me. But after getting back into the hobby and discovering that Polly-S paints were no longer available, I started to look into other options.

Here is what I have tried thus far:

(Let me add that I'm airbrushing all of these in either a Paasche VL or an Iwata HP-CS, at between 10-15psi in all of my many tests. All testing has been done with light, listing coats a varying distances from the test surfaces. None of this seems to have an impact on the results.)

Testors Model Master Acryl Clear Flat Coat:
This was my first effort at finding a replacement for the Polly-S flat clear. Suffice it to say, that I find using anything in the Acryl line an effort in frustration. These paints clog both my airbrushes no matter what I thin them with, and no matter the ratio. The Clear Flat is no different, but it has the added bonus (and honor) of giving me the most prevalent white dusty finish of the flat clear solutions I've tried.

Tamiya Flat Base mixed with Future:
After reading about this, I thought it was goign to be my salvation. But as I've read many places online, getting the right balance of Flat base and Future is tricky and there is a fine line between not enough Future (giving a semi-gloss finish) and too much Flat Base (giving a frosted finish). Over the past week I've poured over these forums and elsewhere, testing just about every mixing ratio I could find...2-3, 1-10, 1-7, 1-5...I think I've tried them all and even made some up as I went along. But I've never been able to find that sweet spot of the perfect finish that so many people say they are getting with their "magic" ratio numbers. I get either a semi-gloss, or a dusty finish. My very first batch of 1 part flat base to 5 parts future wasn't bad, but not flat enough for my tastes...it was more of a "dull semi-gloss" and just had too much of a sheen. Any slight variation from that leads to a dusty finish.

Vallejo Model Color Flat Varnish:
Just got a bottle of this in the mail today, and tried it out after work. Because I'm here writing this novel, you can guess how that went. I also got a bottle of the Vallejo thinner. I thinned the varnish with the thinner, along with some distilled water. Got a very white finish right off the bat. Adding more and more water and thinner, I've ended up with what has to be at least 80% thinner and 20% varnish...still getting a dusty finish.

I'm really at my wits end. It seems that no matter what variations of finish, thinner, distance, planetary alignments I use, the results are always the same...dusty finishes.

So, if anyone can give some insight as to what I might be doing wrong or suggest something I haven't tried yet. Let me also add that Testors Dullcoat is not an option. I use strictly acrylic paints (mostly Tamiya, love them) and Future for a gloss coat...a lacquer isn't going to to help there, plus the fumes aren't something I can tolerate.

Thanks in advance for any words of wisdom that can be offered!

I can't speak for the other brands, but I have used the Vallejo Matt Varnish with no problems. Don't thin it at all, just drop it in the airbrush and go.

Hi

Since you like using Tamiya acrylics, Tamiya launched XF-86 Flat Clear in their acrylic mini range - 10ml bottles.

I've never tried it since I still have enough PollyScale flat coat but once I've run out of PollyScale will give XF-86 a bash since I also you Tamiya acrylics.

I would assume its nothing like XF-21 Flat Base since there is also X-35 Semi Gloss Clear and they added new flat coats to their spraycan range too.

Hope this helps

Hi Bill,

I have used Vallejo GAME COLOUR matt varnish neat through my Aztek for several years now and it has always given a perfectly flat finish. I recently switched to an Iwata and had to dilute it a little with water, but had the same result. How far away are you spraying from? I find that holding the model about a foot or so from the airbrush and misting it more than spraying it gives the best result. Hope this helps.

All the best,

Paul

I use the Testors Model Master Acryl Clear Flat through my airbrush all the time, I do not thin it, I use it straight from bottle through my Paasche VL at about 18-20psi. Never clogged, and always comes out flat.


I should be noted that the Testors Model Master Acryl Clear Flat is being discontinued, and being replaced with Aztek Acryl Clear Flat, which I have found sprays just as well, but not as dead flat as the Testors was.

The one thing you havent mentioned is an 'extender'. Acrylic paints dry extremely quickly which can cause the frosting effect. I use one drop of Badger Accuflex extender in each airbrush bowl of Testors modelmaster acryl paint. The extender does exactly what it says...extends the drying time to ensure wet paint is hitting the surface. It's also a great way of keeping a small amount of any special colors you have mixed in case you need some at the end of the build. I had a small plastic tub (with a lid) of a desert yellow which kept liquid for 2 weeks after I added two drops of extender to the mix. I don't think accuflex is available any more but you can find similar products in good art or hobby stores under 'extender' or 'retarder'. Testors also have one in their product line.

I just ordered a bottle of Tamiya XF86, and will post my findings as soon as I shoot it.

I've been using Testors Glosscoat and Dullcoat (both lacquer)based for more then 40 years, and never had any issues. I do thin them 3:1, @ 18 psi without any issues. I'm switching simply because of the smell even when using paint booth.

Joel

What do you thin your Dullcote with?

I had Testors Dullcote frost badly on me several years ago. I used my usual generic mineral spirits, which I had been using for quite some time. A second coat using a different thinner, Testors own, reversed the issue.

I have been using MM Acryl Flat for a while now. I add a drop or two of MM Acryl thinner and it sprays just fine at 20 psi. wet paint gets to the model and dries nicely.

G

I've used Testors dulcote for ever straight from the spray can without much problem.I had 1 hard lesson at first,that it had to be shaken very well first,my finished model was a write off as it turned into totally white dust.I am going to try something Gino suggested on another post.Modelmaster lusterless flat,#1960.I had no idea it existed and I have yet to find it.

Tom

I have been using Liqutex matt varnish thinned slightly with water and some of their Slow-Dri Fluid Retarder for almost a year now with no problems.It sprays well and is cheap to use.Jeff T.

Thanks for all the responses thus far. I've done some more testing using the suggestions from you all, but unfortunately don't have any real progress to report. My best success (if you want to call it that) seems to have been with my thinned mixture of Vallejo Model Color Matte Varnish with a couple drops of Liquitex Flo-Aid added. Thanks to iowabrit for the extender/retarder suggestion. That seemed to have brought some improvement, but unfortunately I'm still getting a slightly frosted finish no matter what I do.

@viper29_ca:
I'm curious if you're possibly using the Vallejo Air Matte if you don't have to thin it. I have the Vallejo Model Color Matte and it seems too thick out of the bottle for the siphon of my Paasche VL to pull it up into the brush. Haven't felt like tearing it down to try with the Iwata yet, but I suspect it might be too think neat for that as well.

@spacewolfdad:
I do hold the brush about one foot from the model when spraying. But your suggesting it made me consciously keep the distance in mind while spraying. Even with the retarder added, I still get a frosted dusting for the finish.

@SgtRam:
The Testor MM Acryil flat was the first one I tried, and I did try using it without thinning....got horrible frosting. I did try your suggestion of 20psi, but the frosting as still really bad. I had always thought the higher air pressure would cause the paint to dry in the brush, causing clogging and drying before it hit the model, which is why I've been doing my testing at between 10-15psi.

In all cases, I've had no problem getting the flat finish I want. The huge problem is the frosting. Like I said, my best results in the latest round of testing was the Vallejo Model Color Matte with some retarder added. Spraying on my test models, I thought I had it sussed.

But then I tried it on the 1/48 Tamiya GAZ_67B I've been working on, and it frosted. A very light frosting, but just enough to obliterate the subtle washes and streaks I had painted onto it. A quick shot of Future seems to have brought it all back. I think my test models were still slightly frosted from my last testing session hiding how much frosting there actually was. So now I seem to be back to square one.

Reading everyone successes with their various methods, and my apparent inability to replicate them is frustrating to say the least. I may try going back to the Future/Tamiya flat base mixture and live with the sheen that gives. At this point, I'd really rather have a semi-gloss finish that a dusty looking model. I just for the life of me don't understand why I continually get frosting when I have tested with so many variations of mixture, air pressure and spraying distance. I do enjoy troubleshooting, but this really has me perplexed. The constant frosting is the real problem, and not so much the level of flatness to the finish. I want a finish that doesn't alter the coloring of the model...I've seen that and done that in the past, so I know it's possible. I suppose I could build nothing but my airliners where everything is gloss, but I have soooo many other cool kits in my stash! :-)

I will also try the new Tamiya XF-86 as afew of you have suggested. It my LHS doesn't have it and doesn't seem to be widely available in the US as of yet. I did find several overseas sellers on eBay with it, so I may order a couple of bottles this weekend.

Thanks again for all the great suggestions! Please keep them coming....at this point I'll try almost anything.

Both the Model Color, and Model Air Matt Varnish is the very same product, and actually they aren't differentiated anymore as Model Air/Model Color, it is all the same bottle now, but even before that, it was the same product in each bottle.

Just up your air pressure, 25psi should do, have had no problems spraying it "neet" right out of the bottle.

Of course now Vallejo also has new Polyurethane acrylic varnishes in 60ml bottles in Gloss, Satin and Matt as well, but same thing....little higher air pressure, straight from the bottle, not thinned needed.

Testors Dullcoat and Glosscoat are Lacquer based, so you can't thin them with mineral spirits, as that's use with enamels. I thin them with plain old store bought Lacquer Thinner. Works great. No issues except the horrendous odor.

Joel

Grr....just tried that. Nothing but wintery frost.

If you have to up the psi that high, the clearcoat is way too thick, and you're just forcing it through the needle. It also won't flow on smoothly, where you end up with a rougher surface.

I've tried the Neet procedure and didn't much care for it.

Joel

Bill,
I have run into this same issue, I use Future with Tamiya flat and was getting some bad frosting to start. Mine was not so much a dusting but some white spots like runs, I carefully scratched those areas off with a knife and added more Future to the mix it does seem to be a little tricky getting the right mix but it does work.

Cheers Rob.

Well, that was a waste on an entire day. I've literally spent my entire day trying to figure out a solution to the white, dusty flat coat quandary. The only conclusion I've come up with is that I want my Polly-S flat coat back.

I still an totally in the dark as to why EVERY combination of flat coat, viscosity, mixture, pressure, spraying distance, etc. results in a white, dusty finish. I'm posting two photos I took a short while ago to show what is happening. On both test models, the darker, glossy areas are a plain coat of Future that was masked off. In both cases, two different mixtures of Tamiya Flat Base and Future were used. But I also get the same exact results: A white, dusty finish that totally ruins the underlying painting effects. At no point in the hours and hours I've spent on this today was anything CLEAR and flat...just dusty white.






This really can't be that hard. I've tried to follow all the advice in this post and many other similar ones here to the letter, I've remixed three batches of Tamiya Flat Base and Future with different mixing ratios, and even tried mixing Future with the Vallejo. EVERYTHING comes out dusty. Hell, I even tried just a two drops of Vallejo into a cup full of Future and it STILL was dusty. I also tried thinning my various Future/Tamiya mixtures down with 91% IPA. That started to look promising, but in the end, it was either a semi-gloss or you guessed it....dusty white.

I've pretty much given up on the Vallejo. I know some folks rave about it and have said to spray it neet, and I've seen suggestions of thinning it 50/50 with distilled water, but all I get is dust no matter what I do with it.




Thanks, Rob...I wish I was getting just white spots, it would be better that the dusting on the entire surface I'm getting.:-)

What kills me, is I mixed up a batch several months ago that was a good finish right off the bat. I used it all up and needed some more, but just can't get any of the mixing ratios to work. I was really hoping to just find an "in the bottle" solution so I wouldn't have to play Mr. Chemist everything I ran out.

I'm frustrated beyond measure. Sorry to rant, but I've got 30+ years of modeling experience, and have never been faced with such a darned perplexing issue. Seriously, I want my damned Polly-S flat back. Thanks, Testors! Will hopefully have the ambition to try again tomorrow.

Bill,sorry you are having so much trouble.I know it can be frustrating not being ablle to fix a problem.Let me ask you a few questions.
1.This problem just started,yes?
2.It happens with both the Paasche(siphon feed) and the Iwata(gravity feed)?
3.Does the clear go on dry and dusty,or are you putting a wet and shiny coat on and, as it dries, it gets frosty?Jeff T.

Bill,
Sorry you are having so much trouble.
This is the ratio I started with:
3 parts Future and 2 parts Tamiya X-21 flat base,
then added Future as needed. Hope that helps.

Cheers Rob.

PS one other question, have you tried a different bottle of Future?

Thanks, Jeff...to answer your questions:

1.This problem just started,yes?
Yes. I had previously used a Future/Tamiya mixture that worked well, but not totally flat, and have been trying to at least get back to that. Also wanted to find an "out of the bottle" solution so I wouldn't have to jump through hoops to get the right mixture every time I needed more flat coat, so I was looking at the Vallejo as a solution.

2.It happens with both the Paasche(siphon feed) and the Iwata(gravity feed)?
Yes. I switched to the Iwata during my marathon spraying session yesterday hoping the better control I can get with it would help. It was to no avail though.

3.Does the clear go on dry and dusty,or are you putting a wet and shiny coat on and, as it dries, it gets frosty?
Yes to both. Initially I have been spraying with the brush roughly 8-12" from the surface spraying in light misting coats. Doing that I can see the surface turn dusty as I'm spraying. This happens with all the different pressures I've tried, as well as varying the amount of fluid coming from the brush, with or without a retarding agent.

Yesterday to see what would happen, I held the brush closer and sprayed a heavier coat. It turned frosty when it dried, as I expected it to.

With a slightly clearer mind this morning, I'm thinking the key is either the pressure or the distance of the airbrush...or both. Since the dusting happens with every product and every mixture I've tried, no matter how thin and no matter how little flattening agent I use. Pressure and distance seem to be one constant in everything, so I might focus on that.

Not sure if I'll get to it today though. Yesterday was not a good modeling day for me and I might need a break from it. :-(

Thanks, Rob...

Yes, I did start using new bottle of both Future and Tamiya Flat base yesterday. Thanks for bringing it up though. Also have made sure everything is mixed well.

I did start out using the 2:3 ratio but it frosted so I kept adding Future. Also tried a 1:5 and 1:10 ratio yesterday and still got the dusting. I must have ended up at a 1:15 ratio at some point and still got dusting. I kept adding Future to them as I went along but it didn't seem to make any difference other than bringing the finish close to a semi-gloss, but with the dusting still present.

If this was the middle of summer, I could write it off to humidity. But something else is going on that nothing I do seems able to fix. When I try again, I'll focus on the pressure and spraying distance. That seems to be the only constant in all the brands and mixtures I've been trying.

I just can't believe that something so simple is proving so difficult and time consuming, especially when so many others have success that I can't seem to replicate using the same methods. Sort of makes me wish I didn't like using acrylics so much. Lacquers like Dullcoat seem to be a no-brainer that just work. Meh.

But thank you for all the help and suggestions! Will keep plugging away at it though.

Bill,a few more questions
1.Have you tried spraying color on something?If so does the color act the same way,as far as being rough,although maybe not frosting?
2.Are you sure your AB's are clean? Just askin',nothing personal
3.What is the temperature and humidity You are spraying in? Jeff T.

Looking at your pictures Bill I'm getting a bit of this too, only nowhere near as bad. I'm interested in what you find that works.

I found mine got a lot better when I sprayed Vallejo flat straight out of the bottle but kept the coats very light. I'm not suggesting its a solution, only that it helped. Good luck with the quest ;-)

Here's my honest advice as I've heard of this issue before. Seems that it's a condition that is the end result of the Tamiya Flat and Future when their is to much humidity in the air. The White is actually trapped water vapor.

I would suggest that you switch to Tamiya's new acrylic flat, or another product like Micro Flat which I cut with 70% Iso alcohol. As I originally stated, Testors Dullcoat works great, but it's a lacquer based product, so ventilation is a must.
Joel