Humbrol gloss/mattcote taking very long to dry

Hobbes · July 09, 2012, 10:40:53 AM

I've been using Humbrol's gloss/satin/mattcote on a few models now, and I've noticed that it takes weeks (literally) to dry fully. After a day it'll seem dry to the touch, but if I pick up the aircraft and hold it for more than a few seconds, I'll leave fingerprints and the paint will feel tacky.
On my Tristar, I had to do some work after putting the mattcote on, and I left some dirty fingerprints. I was able to clean that up with white spirit, but it looks like I've wiped off the glosscote along with the dirt.

I've thinned the glosscote with Humbrol's own enamel thinner for airbrushing.

I've read somewhere that thinning it with cellulose thinner helps, but won't that destroy my decals or enamel paint?

andrewj · July 09, 2012, 11:08:10 AM

I've got a model of a Seafire FR47 I made over ten years ago and used Humbrol Mattcote to finish it, it's still not really dry , feels tacky to the touch and you can wipe the Mattcote away with a white spirit dampened cloth. I have never used the stuff since, aways now use Games Workshop "purity seal" spray.

Andrew

Dizzyfugu · July 11, 2012, 04:10:08 AM

Recent production stuff (in the new, tall glasses), or older varnish? I haven't had issues yet, but in some cases, when the matte varnish had been resting very long, the stuff needed thorough shaking and stirring, because the thinner/fluid medium and the varnish itself would separate, and when the mix is not right, the coat would end up rather shiny and tacky. The Humbrol varnish also seems to dislike certain enamels - e. g. Revell. I had cases of shinyness, even yellowing, but never issues with Humbrol or Model Master/testors enamels. Just the MM Authentic Tone enamels (esp. the semi-gloss paints) seem to be VERY touchy when varnish is applied.

Hobbes · July 11, 2012, 05:09:12 AM

I bought it a few years ago.

I know it needs a good stir, so I've used my cordless drill with a stirring stick to stir it for several minutes.

I have been using it over Revell enamels, so maybe that's it.

Howard of Effingham · July 11, 2012, 06:03:10 AM

i don't disagree here regards any of the humbrol 'cote' series of varnishes.

i did decide several years back NOT to use white spirit to thin down as that seemed to affect
drying time too.

good stir? well, about 20 minutes or so usually does the trick.

drying time can be aided i think by placing the model in an airing cupboard or similiar.

Mossie · July 11, 2012, 06:16:05 AM

Try putting it somewhere warm before you stir it (like the airing cupboard, near a radiator etc), or placing the jar in a bowl of hot water. I keep mine in the garage and it tends to thicken up considerably when it's settled and cold. Warming it makes it much easier to stir and I seem to get better results from it.

Dizzyfugu · July 11, 2012, 06:17:35 AM

Ah, then I suppose it'd the Revell enamel - its just does not go well with Humbrol's enamel varnish. The symptoms sound very familiar to me, that's why I avoid Revell enamels, if possible, or use water-based acryllic varnish on them.

Hobbes · July 11, 2012, 06:23:47 AM

Quote from: Dizzyfugu on July 11, 2012, 06:17:35 AM
use water-based acryllic varnish on them.

Do you have any recommendations?

Dizzyfugu · July 11, 2012, 07:02:42 AM

Not really. I frequently use an acryllic matte varnish from the rattle can, from Duplicolor (not certain if it is available outside of Germany, and it's only available in 400ml cans in DIY and hobby stores).

I have heard good things about Revell's acryllic paints and the varnish, though (a friend tried them and is very enthusiastic), but haven't used them yet personally, so I am rather careful.

NARSES2 · July 11, 2012, 07:35:47 AM

Quote from: Hobbes on July 11, 2012, 06:23:47 AM
Quote from: Dizzyfugu on July 11, 2012, 06:17:35 AM
use water-based acryllic varnish on them.

Do you have any recommendations?

Harro I sometimes use Windsor and Newton's "Galleria" matt varnish. It's very, very matt and gives a good finish. You need to try it out first on a test piece to get the hang of it though as it can be a little thick

Hobbes · July 12, 2012, 11:46:57 AM

Quote from: Dizzyfugu on July 11, 2012, 07:02:42 AM
Not really. I frequently use an acryllic matte varnish from the rattle can, from Duplicolor (not certain if it is available outside of Germany, and it's only available in 400ml cans in DIY and hobby stores).

I think I can get Duplicolor over here. Have you used it over enamel paints?

Go4fun · July 12, 2012, 01:46:44 PM

Different companies use different formulas in their paints. Mixing a base from one company with a gloos or flat over-coating from a different company can be as bad as putting acrylic over enamel or vice-versa.

Dizzyfugu · July 12, 2012, 11:35:28 PM

Quote from: Hobbes on July 12, 2012, 11:46:57 AM
Quote from: Dizzyfugu on July 11, 2012, 07:02:42 AM
Not really. I frequently use an acryllic matte varnish from the rattle can, from Duplicolor (not certain if it is available outside of Germany, and it's only available in 400ml cans in DIY and hobby stores).

I think I can get Duplicolor over here. Have you used it over enamel paints?

Yes, frequently, e. g. on Humbrol, Testors/Model Master, Tamiya and even Revell (glossy enamel, though). Works like a charm, and it dries up only with a very slight sheen shimmer to it. Not 100% as dull as Humbrol Matt Cote, but very close. Dries fast, no stench, I am a big fan of this stuff and also use it as a coat for dioramas. Only drawback ais that you can get only (around here?) 400 ml cans.