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dull coat issue

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dull coat issue
Posted by NVSRR on Sunday, January 22, 2023 6:53 PM

 I have an issue I never cam eaccross before.   I hve two small half once jars of pollyscale dull coat.    I mixed one up and decided to use it.  applied it and it turned white in places not clear.   I managed to get some of it off.  after thinging it was some kind of reaction. Does not appear to be the case thought.  I though some creative weathering would make it blend in and hide some of it.    Didnt work.   Now what? Anybody ever encounter this and manage to fix it?

 

Shane

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Posted by Pruitt on Sunday, January 22, 2023 7:34 PM

Dullcote can turn whitish if the humidity is too high...

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Posted by gmpullman on Monday, January 23, 2023 5:29 AM

NVSRR
I hve two small half once jars of pollyscale dull coat.

If it's Pollyscale then it isn't Dullcote. Just this weekend I put the "foundation" for weathering three steam locos. I laid a base of Testors 1160X bottled Dullcote thinned with plain paint thinner about 50/50 in an airbrush.

Once that was dry, only about five minutes, I sprayed some PollyScale "dust" over the Dullcote. Now the dust is something I did expect to have a bit of whitish look to it, which it indeed did.

 PRR_J 6488 dusty by Edmund, on Flickr

You can see this around the valve gear where I probably got a little heavy handed but I will reduce this effect later when I apply more of an oily surface here.

I may have gone a wee-bit overboard with the Polly Scale dust effect on this Hudson but since it is a base coat I'm not too concerned about it. I'll tone it down a little with Pan Pastel chalks and more overspray of oily grime.

 NYC_5361_dusty-2 by Edmund, on Flickr

I have a couple bottles of Polly Scale404103 Satin Finish (½ oz.) and 500003 Dust also the larger size 414305 Dust. These are easy to overdo while shooting since they are thin it is easy to put on too much. The 404106 flat finish really needs to be shaken thoroughly. I use a vortex shaker for this then let the bottle sit for ten minutes or so to deaerate.

Dullcote comes in a 1.75 oz. square bottle and requires VOC thinners. I have spotty luck with the little rattle-can Dullcote sometimes resulting in orange peel. I only use these on scenery items now.

You might want to try a thin, airbrushed coat of real Dullcote (1160X) and that might knock down your chalkiness. Can you provide a photo of what your results were?

Good Luck, Ed

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Posted by dknelson on Monday, January 23, 2023 10:01 AM

Whatever you're doing Ed it sure makes the details "pop" on those locomotives

Dave Nelson

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Posted by Mark R. on Monday, January 23, 2023 11:01 AM

That can often happen with old bottles of flat finish. Flat finishes use talc as the basis for the flat finish along with carriers, binders and reducers. What happens over time is that the liquid properties of the original finish can degrade or evaporate leaving a higher ratio of talc than there should be. When the mix is applied and gassed off, the talc comes to the surface and leaves a whitish appearance. usually an overspray of a good mix will bury the exposed talc and the whitish appearance will disappear.

Mark.

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Posted by NVSRR on Monday, January 23, 2023 4:55 PM

These are old bottles of flat finish.    Here is the slug

I didnt try to overspray.   all the white is the talc.  

 

Shane

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Posted by kasskaboose on Monday, January 23, 2023 6:34 PM

How long can you store (in and outdoors) the dullcoat before the white appears on the loco?

That is weird about the white appearance.

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Posted by NVSRR on Tuesday, January 24, 2023 7:52 AM

kasskaboose

How long can you store (in and outdoors) the dullcoat before the white appears on the loco?

That is weird about the white appearance.

 

less than 24 hours after it dries.

 

shane

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Posted by doctorwayne on Wednesday, January 25, 2023 9:18 PM

I still have dozens of bottles of Pollyscale paints, but I don't ever recall seeing a jar of Pollyscale clear finish, either dull or shiney.  I have always used Testors Dullcote and Glosscote and almost always apply it with an airbrush.  If it needs only a slight touch-up, a small brush will suffice.

Wayne

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Posted by Soo Line fan on Thursday, January 26, 2023 7:53 PM

Mark R.

That can often happen with old bottles of flat finish. Flat finishes use talc as the basis for the flat finish along with carriers, binders and reducers. What happens over time is that the liquid properties of the original finish can degrade or evaporate leaving a higher ratio of talc than there should be. When the mix is applied and gassed off, the talc comes to the surface and leaves a whitish appearance. usually an overspray of a good mix will bury the exposed talc and the whitish appearance will disappear.

Mark.

 

 

Can you tell by looking at a bottle if its bad? I have a bottle of Floquil flat and can see hunks of white in it. When I shake it they disappear for the most part. Some remain in the bottom. The others eventually return.

A new bottle of testors dull coat does not act like this. Thinking its not worth taking a chance?

Jim

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Posted by NVSRR on Friday, January 27, 2023 6:59 AM

I don't recommend shaking paint.  It doesn't disperse the pigment in the binder well resulting in uneven pigment concentrations throughout.  Making for uneven color distribution to.  I recommend the little cheap mixers. Micro mark has a version.    It mixes the pigment and binder completely back to the factory ratio blend.   Making even color.   I have Polly scale and cliquish bottles pushing 20 years old.   Perfectly fine nothing wrong with the paint.  

the clumps could be a sign of something wrong.  Or not. Just not getting properly mixed.     If you are unsure, make a test.   piece to try it on. (Something I should have done).      I have a bunch of testers dull and gloss coat. Al, new. And none are any good. Recently purchased purchased too.   The dull coat doesn't dry just gets sticky and the gloss dries to a dead flat finish no matter the application method.  Yet they look fine.   And smell fine.    

 

shane

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Posted by NVSRR on Friday, January 27, 2023 7:14 AM

doctorwayne

I still have dozens of bottles of Pollyscale paints, but I don't ever recall seeing a jar of Pollyscale clear finish, either dull or shiney.  I have always used Testors Dullcote and Glosscote and almost always apply it with an airbrush.  If it needs only a slight touch-up, a small brush will suffice.

Wayne

 

 

I keep forgetting to take a pic of the bottle for you .  It wasn't something very heavily promoted.  

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An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by doctorwayne on Friday, January 27, 2023 3:22 PM

NVSRR
I keep forgetting to take a pic of the bottle for you . It wasn't something very heavily promoted.

Yeah, I don't recall ever seeing it or even ever hearing about it (until you mentioned it, of course.)

I had been using Testor's clear finishes for so long that I never even thought about similar coatings from other manufacturers.

I do have some bottles of Testor's paints, but they're definitely not my favourites.

I have three large-ish (1.75 fl. oz.) bottles of Testor's Dullcote, and another four similar-sized bottles of Glosscote.   Based on what is yet needed to be accomplished, that's probably enough.

Wayne

 

 

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Posted by gmpullman on Friday, January 27, 2023 6:21 PM

Here's some of the selection of clear finishes I have on hand:

 Clear Finishes by Edmund, on Flickr

I use the Dullcote (bottled) or dull/gloss blend 95% of the time. The acrylic finishes I might use on a structure or other detail part but for rolling stock it is strictly Dullcote.

I use a vortex mixer most of the time.

 Paint_Vortex-pollyscale by Edmund, on Flickr

 

 

 Paint_Vortex-ops by Edmund, on Flickr

 Paint_Vortex by Edmund, on Flickr

Regards, Ed

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Posted by NVSRR on Sunday, January 29, 2023 6:28 PM

There you go Wayne.  That is the halk oz bottle of polly scale flat

dont think i will use it anymore.     bit the bullet and et the cost.  go back to water based flat and gloss I have been using.   

 

Shane

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by doctorwayne on Sunday, January 29, 2023 7:40 PM

Thanks Shane...until you mentioned it, I had never realised that it even existed, as I had been using Testors clear gloss & matte for years.  Pollyscale paint is still my go-to choice, at least for the colours that I still have.

Wayne

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