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Wrinkles with certain Humbrol enamels


Beardie

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This is something that I have noticed over quite a long time and I wonder if anyone else experiences it and may have a solution to it.

 

The problem is that I find that certain Humbrol enamels, even after giving them a good few days to dry, will tend to wrinkle and lift if you try to paint another coat over them, The main offenders in my current build, Wingnut Wings Early Sopwith Snipe, are 121 for Clear doped Linen and 98 for PC12. I sprayed them and let them dry for several days and then went to put a white spirit thinned gloss varnish over the top and the paint almost immediately started to wrinkle and lift. I have noticed this effect numerous times in the past, particularly with the light colours like 71 Light Oak and 74 Linen

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I had a similar problem in the past Beardie, it was with an olive/green shade they don't make any more (114 Soviet Green) that I used (wrongly) on a PZL P-24. It actually started to come off the surface on a second coat, after quite a few days :o. Totally off :blink:!

 

I don't know if it will work with all colours, but I tried again using Humbrol's own enamel thinners (after stripping right back to clean plastic with ModelMaster paint remover) and it worked ok. It appeared that that shade didn't (really didn't) like white spirit. Or, at least the one I was using.

 

How Humbrol enamel thinners is different, I don't know :confused: ? Maybe there is another variable I missed; it could be worth trying to change the thinner all the same.

 

Hope you can get to the bottom of it,

All the best

TonyT

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What varnish is it? Perhaps the white spirit may be a little too harsh. Or the varnish isn't totally compatible. When using enamels, I usually use Liquitex acrylic gloss varnish over the enamel, Decals, add weathering, etc, and then humbrol matt cote over the gloss varnish at the end

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Thanks for your input Tony and sapperastro. The varnish was Winsor and Newton Gloss art varnish applied lightly by airbrush. I have had this problem even when just putting a second coat of the same colour on. It only seems to happen with certain colours. I do wonder if, perhaps, the coat was too thin and so the thinners were able to penetrate through to the plastic below and lift the paint up. Humbrol thinners are basically liquid lighter fuel (Naptha) and not dissimilar to White spirit except that it is more refined to lessen the smell and unwanted impurities.

 

The more I think about it the more I suspect that the paint film thickness for those particular colours has to be thicker or it will be too weak to resist breaking up and lifting.

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Ok, I have tried 121 on some cleaned bare plastic, very thin coats, and then glosscote, both thinned with humbrol thinners. No probs. For the record my tin is one of the Hornby tins with the blue stripe at the bottom, not the new UK made blue swoosh label tins. The gloss cote is a new bottle, as are the thinners.

 

So, the variables would be (without looking at how thin your coats are) what vintage your enamel is, white spirit vs Humbrol thinner, and two different oil based gloss varnishes. Just a process of elimination now.

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My 121 is the same as yours with the blue stripe along the bottom, I wonder if it is possibly mold release agent on the parts that causes the problem as I have not been in the habit of washing my parts for some time. I think I might have to start giving my parts a good wash before action from now on.

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