How to fix overthinned paint?

[WelshZeCorgi]

I accidently over thinned a bottle of paint, is there a proper way to thicken it back up?

[Rob G]

Add more unthinned paint. Or let it stand until the thinner evaporates, but that's hit and miss and usually results in abject failure.

[WelshZeCorgi]

36 minutes ago, Rob G said:

Add more unthinned paint. Or let it stand until the thinner evaporates, but that's hit and miss and usually results in abject failure.

Why? What happens if you let it stand?

[dnl42]

If your want to keep your paint in the best condition, only thin the amount of paint you're going to use in a single session. Then discard any excess thinned paint when you're done with the session.

[bmwh548]

Leave the cap off for a while and check on it every now and then. You should be fine.

[Gorby]

1 hour ago, dnl42 said:

Then discard any excess thinned paint when you're done with the session.

I've never done that and never had a problem with reused paint.

If I did it would double my paint bill.

[Jamie @ Sovereign Hobbies]

This depends entirely on the type of paint and what it has been over thinned with.

[WelshZeCorgi]

5 hours ago, Jamie @ Sovereign Hobbies said:

This depends entirely on the type of paint and what it has been over thinned with.

It was Tamiya acrylic paint with tamiya's x20a acrylic thinner. 

[Kev The Modeller]

There's a good little trick with Tamiya, but it must be done when they're new.  Open a new jar and top up with X20A to about 10mm from the top of the jar, I've been doing for a good while now works every time and last as long as the paint does 

[Black Knight]

If its not too far gone you can try adding Artists Acrylic Medium. Its a white/clear goopy paste which artists add to acrylic paints to give them 'body'.

I have a tube and add some to thin acrylic paints which I have bought. It helps a bit. The paste itself dries clear and has no affect on drying time, it merely thickens the paint

[Kev The Modeller]

Just buy another jar and use that to reduce thinner ratio, they only cost $2.50 ish.  

[sapperastro]

Let it stand for a while, stirring it now and again. Tamiya thinner evaporates fast.

[Steve Noble]

Quickest way, just buy another bottle and add it to the too thin one. But in future only thin what you need when you need it..

[RJP]

The worst possible case seems to be the total loss - of a single bottle of paint.

 

You have already seen the error inherent in guessing the amount of thinner to use.  How can you know how much new paint to add to get where you want to be? 

 

You would be better off getting a new bottle and using the over-thinned mixture to thin it, rather than the other way 'round.  You will lessen the possibility of a repeat that way.  Slow and easy works every time.

 

 

 

 

 

[Vladan Dugaric]

Tamiya acrylic paints are lacquers; they dry by evaporation of solvent, so it is safe to let some of the solvent evaporate. If too much thinner evaporates, you can add more thinner, as it will dissolve even fully dried paint.

 

Enamel paints dry and cure (chemically react with oxygen from air), and cured paint is then not soluble in the thinner in the paint; that makes the paint somewhat or entirely unusable, depending how much of it cured, when adding thinner to gloopy paint will not dissolve it any more.