humbrol gloss varnish issues

[Guest]

Not sure if this the place to ask dopey questions, but I am new to forums, so bear with...

I am just nearing completion of a 1.48 Trumpeter Seahawk (nice kit), and did my usual routine with the gloss varnish pre decals, then another coat to seal everything.

First coat was ok, decals on, then second coat applied, at which point the surface wrinkled up in several places, as though the varnish had reacted with itself. I managed to just about sort it out with some careful use of polishing cloths, but still obviously its not ideal.

Theories :

The varnish may be sensitive to changes of temperature ( I work in a summerhouse at the end of the garden, so it can be cold)

Its old stock, and gone off

I tried both spray from a can, and thinned and applied by brush, still the same result.

Any input appreciated !

Also, any suggestions for alternative products

cheers

Graham

[Ian M]

Hi Graham.

I moved this to the painting section.

The only thing's I can think of are either, as you suggested the temperature or maybe the thinners.

Also I stumbled a bit where you wrote sprayed from a can and thinned and brushed on. It could be the spray can one has a different formular than the one in a jar?

Ian M

[Guest]

Hi Ian,

Thanks for moving this to the obvious place (told you I was new)

So, to clarify, all the products are Humbrol (thinners / varnish -spray can and tin) You may have a point about the formula, but I have done the same thing loads of times before, with no problems, and in the same environment/variable temperature.

I think I may try some different products, although I will ask Humbrol as well

Graham

[Guest]

Just a thought Graham.

Had difficulties when varnishing the windows externally when the temperature was low. I put it down to humidity. Even though the surface seems dry it is not & a very thin base of water vapour is trapped between the two coats of varnish. The varnish dries at a differing rate to the water vapour which is trapped.

Or perhaps you have varnished with the heater on then left to dry with the heater off. Air takes up more moisture as it is heated up but then releases as it cools down ie condensation again not necessarily seen by the eye.

Cannot think of any other explanations. That is unless the varnish is contaminated some how.

Laurie

[Guest]

Thanks Laurie, you make a valid point about humidity. I shall have to do some experiments I think !

cheers

Graham

[Guest]

The water traped on the first coat is called "Blushig" and we get it when spraying full size planes with dope if the humidity and temp is to high. It usually leaves a dull "milky" look to the paint.

What could also be a thing is that the first coat might have not cured totally and the second coat sealed in some of the solvents that were still flashing off form the first coat.This will wrinkle the paint.

Theuns