Polly Scale Clear Flat Frosting

[MiG31]

I'm presently working on a 1:72 P-40E, and I'm encountering this problem for the third or fourth time: frosting as a result of mis-use of Polly Scale. This is supposedly the older formulation, requiring distilled water rather than stating that acrylic thinner should be used.

That said, the damage is done, and it is over a layer of Future. I've done a little research on the topic, and the solutions seem to range from cooking oil to an overcoat of Future. Which would work best in this circumstance?

[Triarius]

I'd go with the Future application.

Cooking oil will go rancid, and may do odd things with the paint and decals. While boiled linseed oil will not go rancid, it may well do odd things to the paint and decals.

Another option is light sanding of the affected areas with 800 to 2000 grit, depending on severity.

[MiG31]

It's my understanding that the cooking oil has to be cleaned off afterward, which makes sense given what you've said. The issue there is that the means of removing the oil might damage the Future, which is why I'm leaning towards another Future coat to fix the frosting.

[Frankhenrylee]

I have just encountered this same problem. It seems to cause some silvering in the decals as well. Last night I was messing with trying to fix it and noticed that when I wiped it with windex it went away till it dried. So I hit it with another coat of future and most of it went away, some of the worser areas needed more coats. I haven't put another flat coat back on it so I don't know if it will come back or not. Needless to say I will use Polly Scale no more.

[Mackie]

Oooohh... I'm not sure I'd put decals on anything _flat.

I don't know what to tell you about fixing your problem....

I still use PS Clear Flat. It is dicey but I thin it waaaaaay down with Testors Universal and just barely mist it on. Then I let it thoroughly dry to see what it looks like before I even think about adding another mist layer.

PS suits me because I like a matte finish to my A/C but I know others like a really flat finish. Still looking for a replacement for Polly Scale.

--Has anyone used MM Acryl clear flat? Is it just watered down PS?

[Frankhenrylee]

I didn't put the decals on afterward. I think it ate into the future below the decal causing it to silver. It would seem like an acrylic flat would be the easiest on the decals, but I don't want to go out and buy distilled water for my flat finish. I also like to tint my flat sometimes. I'm going to use MM gloss, then decal, then MM flat next time. Does the MM flat lacquer have any effect on decals?

[GGoheen]

It's my understanding that the cooking oil has to be cleaned off afterward, which makes sense given what you've said. The issue there is that the means of removing the oil might damage the Future, which is why I'm leaning towards another Future coat to fix the frosting.

Sorry to hear of this problem you recently experienced. I can say that I too had the exact same problems with PollyScale clear flat. I know many good things have been said about this product, which is why I wanted to give it a try, but after these same results I switched back to MM clear flat lacquer over Future and have never experienced the problem again. Likewise, I thought that I might be able to salvage the finish by re-shooting with Future but to no avail....I eventually pitched the kit.

Greg

[MiG31]

That's one reason I'm considering alternative flat coats. You say you use MM clear flat lacquer. Does it yellow like some of their other clear products? If it doesn't, how are you applying it?

Edited April 6, 2010 by MiG31

[Spruemeister]

I have used both MM acrylic and lacquer based flats with no poroblems. I've not experienced any yellowing with either. I have much more experience with the Dullcote than the acrylic, and I love it. Works very well over Future. I just used some MM acrylic flat mixed with gloss to come up with a semi-gloss and was very happy with how that turned out. I thinned with MM's acrylic thinner very sparingly. They don't need much at all. The lacquer based clears need quite a bit of thinning.

Rick L.

[Fishwelding]

I'd try adding some future or Polly Scale clear gloss to the flat. It will give it mild satin finish (which I find looks really good), and might prevent the whitening problem you're describing. No guarantees, but worth a shot. I seem to recall a similar problem in the past, and now I never use straight flat, and have not encountered the problem.

As to Testors' lacquer clear coats, I find they are excellent. I've largely embraced acrylics, but have no quality complaints with Testors' enamels and lacquers, and use both when the weather outside is nice.

[Isaac]

Go buy some Vallejo Model Air Flat Varnish. Thin it to 50:50 with tamiya thinner. Works great for me.

Edited April 7, 2010 by Isaac

[Thommo]

Timely topic as i approach the home straight with my Hornet

I bought jars of Pollyscale flat clear and gloss clear maybe 5 years ago, and was most impressed with the flat clear performance

Then some years later, I used it on a B-25 and got horrible frosting/white residue. I was able to fix this by re-applying a gloss coat (can't remember if i used the PS gloss clear or Future), then re-doing the flat after thorough mixing in the jar before diluting in the airbrush cup.

I think one of 3 things causes the white residue problem, but have not entirely worked it out:

1. The flat clear goes off after a while

2. The flattening agent settles out and it needs to be thoroughly stirred before use (ie a bit like No.1)

3. I didn't thin it enough.

When i come to aiming it at my Hornet, I'll be mixing the hell out of it, and starting with a very dilute mixture.

Was down at the hobby shop this week pondering switching to Testors Dullcoat (in spray can) ot Tamiya flat clear (also in spraycan), but will go with the Pollyscale again this time and hope for the best

[Triarius]

Thommo, I suspect you are on the right track. Flat pigments tend to settle and flocculate ($5 word for clumping) fairly readily, since they are an amorphous form of silica that wants to be crystalline. (Given sufficient time, it will be.)

So mix the @#$%! out of it. This is one area where I really recommend using a powered stirrer. And strain it before it goes into the airbrush!

[Old Blind Dog]

Yep, Thommo is right on the money. I've never had a frosting problem with Polly Scale clears through the airbrush, but I employ thorough thinning and stirring as SOP. Over time, the "pigments" tend to settle and need to be re-combined with the carrier. I thin with Tamiya X-20 A to the consistency of skim milk (about 15 drops to a new bottle; older bottles may need more). I then stir (NEVER SHAKE) with a clean craft stick.

The only time I've had trouble with PS clears and frosting was when brush-painting the PS over areas with still-fresh (unevaporated) decal solvent. Impatience will get you in trouble every time.

Triarus is also right on; occasionally, straining may be required as older bottles have a tendency to clump up.

cheers

Old Blind Dog

Edited April 8, 2010 by Old Blind Dog

[madmike]

The last applications of my PS flat clear resulted in frosting even after long periods of mixing so I tried Vallejo flat clear to put the clear finish on my recent Platz 1:72 Predator build. The Vallejo needed a number of coats for the flat finish I wanted but worked well.

I now believe frosting can occur when too heavy a coat is applied.

[GGoheen]

That's one reason I'm considering alternative flat coats. You say you use MM clear flat lacquer. Does it yellow like some of their other clear products? If it doesn't, how are you applying it?

No, MM clear flat lacquer does not yellow the finished aircraft nor the decals. I thin with KlearStrip/hardware store lacquer thinner approx. 3:1 without any problems...and never any frosting.

Greg

[MiG31]

No, MM clear flat lacquer does not yellow the finished aircraft nor the decals. I thin with KlearStrip/hardware store lacquer thinner approx. 3:1 without any problems...and never any frosting.

To be certain, you're referring to lacquer thinner like this? Given my experience with the stuff, I'm hesitant to let that near anything made of plastic.

[GGoheen]

That's the stuff....buy it by the gallon and transfer to a smaller container to refill my recycled eye-dropper bottle for thinning paints to be airbrushed. Never had it melt plastic yet in my years in this sport.

Greg

[UKPonchoMan]

I've had these problems here in the UK with both the Polly Scale Flat (green bottle?) and the Model Master (red?), both from brand new fresh bottles too!

I have a possible solution to try out - mix and thin ready to spray then head up your container in some hot water. I've had problems with Humbrol GlossCote remaining tacky and I found that warming it up caused it to dry perfectly - I wonder if the same thing might work for Polly Scale / MM ??

[Old Blind Dog]

I have a possible solution to try out - mix and thin ready to spray then head up your container in some hot water. I've had problems with Humbrol GlossCote remaining tacky and I found that warming it up caused it to dry perfectly - I wonder if the same thing might work for Polly Scale / MM ??

This is good advice. Generally with Polly Scale, the warmer the paint is the better it behaves. It certainly atomizes more efficiently.

cheers

Old Blind Dog

[Cunumdrum61]

Didn't the formula for PS clear flat change recently? I tend to use the Gunze clears and never had a problem with them. Their flat is really good and dries quickly.

[balls47]

If you use Dullcote, make sure that you dust it on. If airbrush it on and it looks wet for very long, then, yea, it will attack stuff.

[Triarius]

Didn't the formula for PS clear flat change recently?

Yes. The Polly Scale line was reformulated in 2007. However, I have used both formulations of flat and satin and found little difference.

[MiG31]

An update: I sprayed the affected areas with Future after some judicious wet-sanding to try to mitigate the worst of the frosting. The results were mixed. While the Future did improve matters, there were some nooks and crannies that still contained a bit of frost. Some dry-brushing helped with this, and while it's not perfect, I think it works out overall, given the plane is heavily weathered.