Is a solvent paint more "searching" than water, causing AB leaks?

[Guest]

I have been experimenting with Tamiya Black Gloss, TS 14. Its in a spray can. Its solvent is Cellulose Thinner. It is capable of producing good results from the spray casn, nice and glossy, but I wanted to spray it through my AB (more controllable). I decanted it and sprayed it through by AB (0.4 mm nozzle). The front of the AB immediately leaked, a lot. I don't know from where exactly. The whole of the outside of the front area was covered and paint was dripping down. This has never happened before with acrylics and immediately after and I successfully used the AB to spray a coat of acrylic paint (glossy) with no leak. The screw at the nozzle was as tight as usual. I might have to replace the aircap "O" ring.

Generally, a solvent will find a path or a leak more easily than water, probably because it is thinner (less viscous). Has anyone had unexpected leaks from an AB when using a solvent-based paint?

[Ian M]

Hmm I have had it happen a couple of times with Alclad that stuff is pretty thin!

I think I solved it with a good clean.

Failing that a quick and nasty fix is a drop of liquid mask put as a very thin film on the leaky bits.....

Ian M

[ojays]

If your seals are 'Rubber' then cellulose will soften them and leak.

If they are 'Teflon' you are safe.

I used to use airbrushes in my trade, and only used makes with 'Teflon' seals for this reason.

Another problem has been mentioned on another post lately, that over tightening the nozzle/cap will compress the seal to a point it will leak.

Hope this helps.

Gregg

[stona]

^^^^^^^^^^^ Exactly

Steve

[Guest]

All my seals are solvent proof. I replaced the aircap O ring, and flipped the washer at the rear end of the nozzle. I sprayed Tamiya lacquer again through the AB with no problem. So perhaps it was the O ring. That is consistent with earlier blow-back of air in the colour cup which I have had for some time and which has now disappeared. I think I might have overtightened the aircap in the past. Thanks for the help.

[Guest]

Steve first replace all seals once a year. They cost nix. They get tired.

Suspect that the compressor pressure is to high. I think from memory you use acrylics of the Vallejo type. Quite heavy compared to the Tamiya solvent type. The acrylic resin is quite a gungee medium and needs, I have found, a much higher pressure to get it through. Place a drop of thinners from Vallejo on a top leave it to dry and there is a residue mound left. Do this with Tamiya thinner and I would bet there is nothing left after it has dried. Try lowering the pressure. That would be my guess. Also with the thin solvent I would experimant with a .2needle/nozzle.

[Guest]

Thanks. I used 20 PSI, the same as for Vallejo acrylic. I will try lowering it next time.