Can I permanently thin paint?

[Valkyrion]

I've got a new unopened bottle of Corax White - can I immediately put a thimble full of water directly in the pot? 

I'm not sure if I come to the paint pot again in 6 weeks or months time that it won't have done something funky to it, or have other adverse effects.

[Oxydo]

You can, but I would use the corresponding medium instead since that's just transparent paint which means you only dilute the pigments instead of changing paint composition and hence its behavior.

I've watered down paints "permanently" with both medium and water, depending on what I'm using them for and if they are fresh or have dried out a bit.

 

For example, today I've mixed some Akhelian Green contrast with contrast medium to achieve the proper level of opacity that I want for my LI models. Ended up at around a 4:5 ratio that now has its own bottle.

Adding water makes the paint more runny , so if you're panel lining that might be what you want to do, which I've also done.

[Bryan Blaire]

Yes, you can, although like Oxydo said, use medium, not water.  You can also throw some thinner and/or flow improver in there as well - I prefer to use a mix of mostly medium, plus just a little bit of thinner + flow improver, in any paint I usually use more thin, even ones I put onto a wet palette.

 

Also toss in some kind of stainless, rustless agitator while you are at it, because thinning down almost any paint in bottle is going to separate over time and require agitation to get back to “right” for painting purposes.  I do that to all of my paints, regardless of bottle type or any pre-thinning happening, just as a matter of practice, and it’s always served me well.

[MithrilForge]

all above comments are true... But GW sells thinned down paints...it's called AIR Paint... But you can do the same thing with adding Lahmian medium to your pot... 

and a stainless steel ball... although GW should add them anyway (especially due to the prices they charge )

 

M

[Firedrake Cordova]

I'll echo what everyone above has said.

 

If you're going to add water to the paint, your best bet is to use distilled water rather than tap water, as this should contain fewer impurities (the paint should contain an amount of biocide, but every little helps). Whilst you can use water, if you add too much it can change the properties of the paint - adding an acrylic medium would be better, which in GW's case is Lahmian Medium.

 

@Bryan Blaire's suggestion of adding a little flow improver if the paint is a bit on the thick side is a good one, too.

[Tyriks]

I am terrible at mixing paints consistently so I have been mixing up a big batch when I start a project and usually add some medium (lahmian or contrast, as appropriate) and haven't had any issues doing this. You can find empty bottles/jars to mix them into easily enough at craft stores or online.

[sarabando]

just go slow with adding your thinning medium as its very easy to over thin and be left with a glaze