I use the putty of Tamiya and when it is very hard (mine is always), I put a little of it an a flat surface, as a glass piece for instance, I moisten a spatula in acetone, kneading the putty until it to be soft. Taking care for just to moisten the spatula because a lot of acetone maybe can damage the plastic of the kit. Some other method?

Goucho ,

An other methode is to add some of your glue wich you fix your model with to the putty .
The glue i use is Revell and this methode works perfecly for me .

All the best and good luck

Eric

When I have to soften it i use acetone. Thinned like this the putty can reach a very liquid consistency and can be even applied with a brush for very precise works. On top of that you can use a brush dipped in acetone to "thin" excessive buid up of previous putty application...
Ciao

I often use glue, as Eric does. But sometimes when I just want the putty on a little spot, I use turpentine.

For relatively small gaps, better use glue.

With Squadron putty, have used Lacquer thinner effectively as a thinning agent - doesn't evaporate as fast as acetone - don't know how it would work with other fillers...

:-)

What do you guys use to thin out milliput that stuff is hard to work.

I mix a little Testors liquid cement with the Squadron white putty.