While on the subjects of putty's........

You can transfer the putty into a new tube. Get an old plastic toothpaste tube (just replace one used tube at the house). Cut off the flat end. Slit your putty tube open, and remix the putty and the solvents and carrier. Push that mixture into the new tube, getting out all of the trapped air. Roll up the flat end, and secure that with a binder clip.

you can do this right away when you open a new tube of putty, and it will last longer. Cut the flat end off, "round out the shape of the tube", and roll the end up and secure with a binder clip.  Then, when the putty starts to get old, you can poke a steel stir stick in there and remix it. (or remove it, remix it, then return it)

Rex

I will say that I haven't had that issue w/Tamiya's putty. Squadron's has been giving me fits with that issue.

BTW, that is a cool tip, Rex.

Keeping the cap on except while actually taking putty out of  tube helps.  Even when it has dried at the surface of the neck, I have found that cutting out the resulting plug allows me to resume using it.  I would think squeezing out the contents to put it in some other container might expose the whole content to air during the transfer, unless the transfer is done in an inert atmosphere, which might take quite a fancy piece of equipment.

Used the idea for about 25 years.  Ever since I saw a cake decorator use one of those papers wrapped around the frosting "squeezers" to write on a cake.

The brief exposure to air is less of a problem than leaving set up putty in contact with "new" putty, and less of a problem than leaving the putty's components separated out.

Ignore my tips for another 25 years, by then they might be fully vetted.