Tamiya Thinner goes bad?

You haven't cross-contaminated between acrylics and enamels have you?

Tamiya actually has both types, ie. acrylics and enamels. They're not available in all countries (eg, not available in the US), but in locations where they are, they're often sold side by side.  

The acrylics come in round jars and the enamels in rectangular jars similar to the old Testors range. The thinners are not cross-compatible. Acrylic thinners are labelled X-20A and enamel thinners are labelled X-20  (in the 10ml size it has a clear cap, but larger sizes have a blue cap).

I did have a problem a while back with Tamiya thinners, have a look at the link below

148449.aspx

In the end I tracked it down to the cleaning of the airbrush. Now after I clean it with water I run through some Vellejo airbrush cleaner and I haven't had the issue since and I'm still using the same battle of thinners too. My guess is that it was some weird reaction with something in the water!!

Hope that helps

Phil

i rarely use tamiya x20a for spraying anymore, just IPA, i ALWAYS use ipa to thin it when handpainting .

Thanks for the suggestions gents... Talentless what is IPA?  alcohol?  I use acrylics exclusively, Model Master and Tamiya.  When I clean my airbrush - the last thing I run through ( after a bit of windex ) is either the MM or Tamiya thinner or cleaner.  

But here's the thing that has me buggered: there seems to be a strange reaction even in the cap of the bottled paint when I use it.    I guess I should just bite the bullet and go get a couple new paints and thinner (these are nearly 3 years old by now, if not a bit older) and see how that works.  I thought I read that the Tamiya thinner is not sold in the US anymore?

Sorry, yes ipa is isoprpoyl alcohol.