Polyurethane over NC Lacquer

I have two hoop pine bathroom vanities that have been sprayed with Feast Watson Oak Proof Tint (1 part tint:9 thinners) then sprayed with a nitrocellulouse lacquer (1 part hardener: 9 parts lacquer).

After a couple years use the N C lacquer has not handled the wet area and I need to completely resand the tops to bare timber, stain and recoat.

I am wanting to use a two pack polyurethane (ie:Wattyl 7008) to get better wet area protection. Or something else that is even better still.

Will polyurethane adhere to the newly stained timber since I will use a thinners base mixture when staining?

What type of prep do I need to do to the parts of the vanities that are in good condition to have polyurethane adher to NC Lacquer?

The reps tell me that I need to take it back to bare timber and start again but there must be another way?? Thanks :)

i don't think anything will agree with the NC lacquer, and may react, tthe rep. seems to know this...

just another point, it's actually easier to start again then to fix a stuff up if it accurs, i stuffed up a table top the other week, and instead of trying to fix it, i got a card scraper and removed the whole finish, only took about 20min. and then redid the finish, this time with success...

Starting again may be the only way by the sounds of it.
What then is the best finish for stained hoop pine in a wet area?
Spray or brush?
Thanks Again

Polyurethane is probably the best finish available to us to use on a surface as a finish.

The wattyl 7008 would be OK though a marine 2 pack which is designed to resist water would probably be better for your bath area.

Wattyl put out a booklet on finishing timber surfaces you should be able to get a copy from a large hardware/paint store if not contact wattyl. They should have an email address you can go to. Same goes for any other brand paint check the products to see if what you want to do is OK.

La Huertu is on the ball, start again from bare timber.

It is possible to put some finishes over others, whether is a good idea is another thing. generally if you mix types of finish you get one of three results

The new one reacts with the old and it all goes mushy and stuffs it completely.

It appears to work but down the track peels off because it dried on top without gaining any great adhesion

Or it works and nothing really appears to have happened, but you still have what amounts to a ham sandwich, several types of material not all really working as well as they should as there is other weak finishes underneath.

As to spray or brush, don't spray 2 pack products in a confined area unless you have the correct gear ( an air fed pressurised mask ) supplied with air breathable compressed air. You will also use miles more material than brushing, (50% loss in overspray) and you will have clear over everthing within the bathroom unless you cover it up and that includes you.

The wattyl poly will have instructions on it to make sure you apply it in a well ventilated area even when brushing. Usually with timber brushing works far better as you can use the hair of the brush to rub the clear into the grain, with spray you will get pin holes/ bubbles as air will blow back out of the grain preventing the paint from getting in.

When you strip the old finish, do a test with the poly to see if it's going to give you any trouble. Could be the NC laquer has worked it's way into the wood and you won't be able to remove it without some serious work.

If it doesn't want to play ball, a coat of dewaxed shellac should seal it, and stop any more problems from occuring.

Don't worry about the fact that shellac is not durable enough for your application, it's just there as a sealer and won't affect the final finish nor it's durability. Just make sure it's a light coat and you don't miss any spots. Sand very lightly afterwards to take off the bristles and help give the poly something to grab onto.

It's an extra step, a bit of a hassle but it does work if you get problems.

If nothing goes wrong, then don't bother with the shellac. :D