spraying future...

I use Sunnyside Denatured Alcohol Solvent avilable at most hardware stores in this area, not sure what brands may be in Portugal. Windex should also work, the ammonia content is fairly low, but Iv'e never tried it myself.

Holy crackers! Theres a lot of future questions! Go to the sticky thread "the complete future" in techniques for everything you want to know about it. Couldn't find my future question's answer there, but it should have everything you need to know about using it.

I clean mine out with Windex, and then just spray some water through it to wash the Windex out. I use mostly acrylics, so I've always got a big bucket of water sitting by my bench. Just dunk the whole airbrush under water and spray a few seconds to wash out the Windex, then blow some air through it to dry it.

Windex will work but as you stated it can harm the chrome surface over time is used repeatedly, although I don't think it happens too often as I have never heard anyone complain about the ammonia attacking the chrome.

As Rick stated, any thinner like that will work including mineral spirits, lacquer thinner and others. Any acrylic paint cleaner will work also.
I don't know if you have Simple Green in Portugal but a mixture that I have mentioned on this forum before is 2 parts distilled water, 1 part Windex and 1 part Simple Green cleaner. It works very well for acrylics.

Mike