Time was we all had to use Glass Plus to clean our planes with. Now, I read from Granderson, et al, that we're supposed to clean with Windex (six times?) before you apply the paint. Of course, Windex now has a variety of products, to add to the confusion.

Comments please from you finishing Guru's!

 

Quite?

When prepping a surface to paint, typically I will wash with a soap and water solution, NO dishwashing soap, it has additives to promote water sheeting, They concern me as they can leave residue. then I will use two clean lint free towels, one saturated with prep solvent, and the other dry. the "ultimate" method is to wipe only one direction, flooding the surface with solvent then with the dry towel wipe the same direction to push the contaminants that are emulsified off the edge of the surface. I use a torx product paper towel for cleaning. Make sure that you allow the surface some time to evacuate all the solvents before you attempt to spray on them.
FWIW I dont use PPG prep sol

Which Windex?

Just the regular Blue Windex.  This is to clean after sanding filler coats.  It is also to clean the color coats just before you spray the clear.  Degreasers don't remove dust and sanding residue.  I suppose other glass cleaners might work but Windex (the regular Blue stuff) is a sure thing!  I've bet my last 12 finishes on it!
P.T. Granderson

So now we know!

Tanks!