November 27th, 2006, 04:26 PM
could anyone tell me if it is possible to spray a polyuretane clearcoat over a nitro celulose clearcoat.
November 27th, 2006, 04:47 PM
Shouldn't be a problem........... especially if the nitro is well cured.
November 27th, 2006, 05:02 PM
November 27th, 2006, 07:28 PM
I wouldn't do this without testing in an inconspicuous spot. Depending on the 'poly' - remembering not all are constituted of the same products, you might find the nitro remelts with the poly's thinners before they flash off, and then jellifies and won't harden - or worse, softens and wrinkles and lifts off in patches.
Nitro over most dried poly is fine, because once a two-part finish catalyses, it becomes pretty much inert and impervious to acetone, which is the thinner used for nitrocellulose paint.
If you want a tougher topcoat, clear nitro used by furniture refinishers today often comes with polymers in it, plus UV filters which toughen it and slow the aging, but it still uses a compatible thinner to old nitro so won't make it 'blow up' or react.
November 28th, 2006, 01:31 PM
If the nitro is well cured you are all right. If it's a fresh finish, I'd stay away from it. Don't ask how I know, but I'll not forget the mess!