Paint skinning. Anyone know why ?

[Smallfry]

I have recently been painting odd things with spirit based paints, by that I mean thinned with white spirit or similar.

Been going on for years, but does anyone know why some part used tins seem to survive for years without skinning over, and others skim over in a few days/weeks ?

I am always fastidious in cleaning the top and rim of the tins, even more so if I know that it is not going to be reused for some time.

Different types of paint or is it conditions ?

 

[Endeleus]

I always tip the can upside down for a few seconds before putting away on the shelf, that usually guarantees a good enough seal on the lid to prevent a skin forming in storage.

 

[zzr1200]

I always shake the tin after refitting the lid, helps to seal any slight air leaks around the lid, that might allow evaporation/skinning of the paint.

 

[ajlelectronics]

I store cans of paint and contact adhesive upside down.

 

[Gareth J]

I always put it down to contamination I don't know what; moisture, dust, air maybe.

Always reckon that the longer you have the lid off the more of a contaminant load there is in the paint. Painting with a brush from a tin seems to almost guarantee skinning.

If it's moisture related, making sure the tin is warm before opening might help reduce condensation on the surface when it's opened.

This is all very much speculation and I've not properly noticed any definite relationships.

 

[Maxakarudy]

Oil based paints cure in oxygen environments, not by solvent evaporation, the more air in the can the quicker the skinning occurs, hence new cans don't
skin until open as there is very little air in the can.

 

[steveo3002]

some seem worse than others , i do the upside down trick but doesnt seem to work always

anytime its really mattered i order some smaller tins and decant the left overs so theyre full to the brim

 

[Gritineye]

I've had some success with laying a plastic bag on top of the paint before fitting the lid, spread the bag out to the edge with something.

 

[Erie Fred]

I have seen others take their TIG torch and flow some argon in the can just before closing it up.

 

[ajlelectronics]

some seem worse than others , i do the upside down trick but doesnt seem to work always

anytime its really mattered i order some smaller tins and decant the left overs so theyre full to the brim

Lost your marbles? A good handful added to the tin will decrease the quantity of air.

 

[DanZac]

Lost your marbles? A good handful added to the tin will decrease the quantity of air.

It's cheaper to buy new paint than marbles.


(Unless you happen to have a bucket full in the man cave that you've hoarded and constantly tripped over for the last 50 years just in case they come in handy, but I can't imagine that would apply to anyone on here).

 

[brightspark]

I store cans of paint and contact adhesive upside down.

and on a hot day it expands and blows the lid off or leaks if its not sealed properly

 

[dave h 2]

and on a hot day it expands and blows the lid off or leaks if its not sealed properly

Aluminium paint party trick.


Some paints dry, others oxidise

 

[RichardM]

My great uncle used to be a painter and decorator, always used to store part used time upside down.

 

[Rrobson]

As a few have said, store them upside down. You also don’t get lumps on the lid falling into the paint when you open it next time!!!

 

[Smallfry]

I have seen others take their TIG torch and flow some argon in the can just before closing it up.

Now theres a good idea. Will try that, but with Argoshield.

 

[Smallfry]

All interesting stuff and I guess it depends on the paint formulation.

I have never done the upside down trick, as I have had a few lids fly off in the heat. Would make quite a mess !

Have got the semi underground cellar/utility room which would be better temperature wise, but probably not a good idea to store a lot of paint in the house.