another thing, don't mix the alcohol straight with the paint. Mix it 1:1 with windex or water.
I have 2 paint bottles within reach with the following.
1) 1:1 mix of 70% isopropyl alcohol/water (I use this to thin fastint)(yes, I reduce fastint)
2) 1:1 mix of windex/water (I use this to reduce everything else parma)
hope this helps