Varnish vs TSP

[Azura]

My boat is presently dry and unvarnished. The decks are fiberglass in need of paint. The paint manufacturer says I have to wash the decks with TSP (TriSodium Phosphate) prior to painting. My teak trim is sanded bare now. Do I wash everything now and risk raising the wood grain or do I put several coats of varnish on the wood and hope that the TSP doesn't mess up the varnish?

[AirborneJarhead]

I know I'm probably stating the obvious, but shouldn't the teak trim be removed? I ask because I'm about to paint my deck and cabin trunk and anticipated having to remove hardware and teak. If I can do it without removing the stuff, I'm all ears!

[JohnPen]

I removed all my teak trim a year ago, sanded, 8 coats of varnish, reinstalled. looks great! Only real challenge was finding a decent bedding compound that would work (3M 101) Polysulfide.

You will thank yourself for removing it and doing it the proper way.

[Azura]

The small teak items, all winches, and hatches have been removed. The boat still has teak coaming pieces and a teak cap rail. I am not removing those. I'm leaning toward varnish first.

[Faster]

Seems to me you could either a) mask off all the teak trim with a poly sheet and waterproof tape, wash your deck and paint it or b) varnish all your teak, let it cure, then repeat (a) above.

[Parley]

I would be concerned about the tsp removing the "sheen" of any varnish that has been layed down. I would apply the first couple coats of varnish (to somewhat seal the teak), mask it off, complete the deck painting, remove teak masking, mask deck around teak, and complete the teak varnishing. All will be good.

[ehmanta]

I would neveruse trisodium phosphate on or near the water due to environmental hazards (harmful to fish etc). They due make a substitute for it however that is phosphate free. good luck.

[hellosailor]

I'd call 3M. For two reasons: they make all sorts of tapes, and I second the concept of using a waterproof tape and poly, since you WILL have to mask off the teak anyway. In fact, 3M makes a "blue" masking tape with poly attached to it, so you can do the masking in one shot. (Any hardware/paint store.) But they also make more durable tapes. If the tape will be left in place exposed to sunlight for more than a week, you want a more durable tape so the gum doesn't transfer to the wood.

3M also makes a full line of painting and refinishing supplies including "prep/solve" a solvent that removes all waxes and polishes from fiberglass to prep it before painting. Yes, you can use that instead of TSP, which is banned in many states anyhow. It will cost more--but like most solvents, it shouldn't raise the grain of the teak. You could probably clean the deck with prep solv and clean rags, THEN mask the teak after it had evaporated off. (Should also clean the teak well enough to get the tape stuck down nice and tight after.)

****'n'span used to be mainly TSP, the ban made then switch formulas AFAIK.

[sailingdog]

It depends on what kind of paint you'll be using. If you're going with a two-part linear polyurethane paint, I would remove all the hardware and wood. The paint really works much better if it is applied to the entire deck, rather than applied to the deck around things like deck hardware, and will last much longer. It is a lot more work, but that's what I would do.

I don't think that TSP will harm varnish as a general rule...but it isn't very friendly to the environment.