Frosting on matt varnish

[Spaceowl]

(I realise that title is probably going to look strange to our New World members )

I've noticed the last couple of times I've tried to matt varnish things with Humbrol spraycans that I'm getting a sort of frosting forming as the varnish dries. What is causing this to happen? Any steer on what I'm doing wrong, all help gratefully accepted.

[iggie]

I've no idea what causes it, but I've had the same with Humbrol spray gloss. I no longer use Humbrol spray products, and would you belive it, the problem has stopped

[Andy Dighton]

I've also had the same. I've given up with Humbrol varnish.

[TeeELL]

I have a suspicion that it is all to do with humidity. A few years back I was building an Airfix Hurricane as the ‘presentation’ aircraft for Mussolini. The afternoon before I did a test spray of Humbrol Mattcote which worked very well. Overnight it rained and the following and time critical day I did exactly the same spraying - to my horror the model ended up with a white finish.
I still use Humbrol Glosscote and Mattcote but I monitor the humidity.

[Stuart]

Tony's probably got it spot on, but as the others have said, I've given up using all Humbrol clear products except their enamel based clears - I just find them too unreliable. tbh I'm a bit worried about the red Humbrol spray can I've purchased for my Red Arrows builds - but I'll take Tony's advice.

If in future you want a decent set of clears that are reliable, try the Mr Super Clear cans. I've been using them all year on about ten or so models thus far and have not had a single issue with either the Gloss (I'm on my third can of gloss), Semi-Gloss or Matt - and I have used them in the garage on a cold and damp days. I'll be interested to see how they perform over the winter.

I do keep them in the house where it's warmer before I spray, and I do keep the coats light (although with the gloss one light coat is generally all I've needed).

[Andy Dighton]

. tbh I'm a bit worried about the red Humbrol spray can I've purchased for my Red Arrows builds - but I'll take Tony's advice.

TBH I've never had any problem with HU19 from a can.

[TeeELL]

Stuart,
are those acrylic varnishes? If so, have you used them over enamel paints at all - if yes, did they react?

[Stuart]

. tbh I'm a bit worried about the red Humbrol spray can I've purchased for my Red Arrows builds - but I'll take Tony's advice.

TBH I've never had any problem with HU19 from a can.

That's good to know!

[Stuart]

Stuart,
are those acrylic varnishes? If so, have you used them over enamel paints at all - if yes, did they react?

Good point Tony, no I haven't as I only use acrylics - can't comment on if they'd work over enamels.

[Stuart]

Stuart,
are those acrylic varnishes? If so, have you used them over enamel paints at all - if yes, did they react?

Good point Tony, no I haven't as I only use acrylics - can't comment on if they'd work over enamels.

Oh actually - that's not entirely true. I have used it over Tamiya Lacquer based sprays and Citadel sprays as well - with no ill effects. Alas I no longer have any enamels to try it out on, otherwise I'd give it a go and let you know.

[TeeELL]

Thanks Stuart. I am assuming they are acrylic sprays as I cannot find any confirmation in the descriptions I’ve seen.

[Spaceowl]

Tony's probably got it spot on, but as the others have said, I've given up using all Humbrol clear products except their enamel based clears - I just find them too unreliable. tbh I'm a bit worried about the red Humbrol spray can I've purchased for my Red Arrows builds - but I'll take Tony's advice.

If in future you want a decent set of clears that are reliable, try the Mr Super Clear cans. I've been using them all year on about ten or so models thus far and have not had a single issue with either the Gloss (I'm on my third can of gloss), Semi-Gloss or Matt - and I have used them in the garage on a cold and damp days. I'll be interested to see how they perform over the winter.

I do keep them in the house where it's warmer before I spray, and I do keep the coats light (although with the gloss one light coat is generally all I've needed).

That's good to know, Stuart - do they have a UK stockist?

[Stuart]

That's good to know, Stuart - do they have a UK stockist?

I don't know about individual stockists, but there are plenty of UK based sellers on ebay which is where I get mine from.

[JohnRatzenberger]

FWIW, with any rattle-can paint or varnish, I always warm the can in a sink of hot water, then shake well, before using.
I had too many frosting instances (with over here products) in the past to skip that step.
FWIW#2, my current varnish is Modelmaster from a rapidly diminishing # of jars, through my airbrush, and I am not having the problem for the while.

[iggie]

At the risk of being labelled a safety killjoy, can I just suggest that if warming any aerosol in water that the water should be significantly lower than 50⁰c (122⁰f) to avoid potential for rupturing the can. I know everyone on here is unlikely to need this advice, but visitors to the site may not be as experienced or aware.
Allowing time for a can to come up to average room temperature naturally is probably a better option, together with shaking as necessary...