can floor boards be sanded?

[anaisdog]

my floor boards are in bad shape and i took them off the boat.  can I sand them to get out these weird black footprints (PO somehow did that) as well as other nastiess and then revarnished.  on the advice of someone, i bought Rustoleum Spar vanish, only to read the can just now to read that it was exterior only (opps).  also, there is black mold on the bottom of the board that was by the head, what do i use, besides just sanding, to kill that off and is there any reason not to put the polyurathane on the underside of the boards as well?

[Noah]

Yes will need to sand. And kill mildew/mold with a bit of diluted bleech. RE: standing: be careful on how aggressive you get, as they are just thin veneer over plywood. If they are pretty far gone (but verneer is still good enough to refinish)--and you want to get an even color--I would use paint stripper to remove all of the old finish, restain them to color desired or leave "natural". Then recoat with 5 (+/-) coats of urethane or marine varnish. Nothing wrong with using an "exterior" varnish on interior. It is actually preferred, as it wears better. I like to use Epifanes  wood finish matte. It can be recoated within 72 hrs without sanding between coats. Also, Yes, put a couple of coats on the underside and edges too, to preserve against moisture.

[KINGAIR350]

Recommend a heat gun , gloves and a cabinet makers scraper used vertically ,  heat up the old stuff till it bubbles and  scrape off old top coat and lightly sand , and use the sealer for the under side of floor boards several coats . Let cure 100% and flip over to top side and start your process good luck.

[Indian Falls]

I  redid mine last winter.  I used both the heat gun method of stripping and the "green" stripper you can get at the hardware store.  I would not use the green stripper. It requires you to wash the stuff off with water.
The result is the holly swells up higher than the teak and now the panel is not flat.  i could not sand or scrape enough to get the raised holly level with the teak without ruining everything.  So it is what it is.
The heat gun scraper method was better...BUT  if you stop moving with that hot scraper even for a second you will leave a mark in the wood that you cannot sand out.  
I killed mold on the undersides and sealed the panels all the way around.  Boy did mine stink on the bottom side.  Sealing for that reason alone was enough for me.  I used Minwax polyurethane for floors.  6 to seven coats wet sanded with 400 between coats.  Turned out awesome.  I also followed advice to fill dents and defects with epoxy.  Bad Idea.  It will not sand and it will be darker than everything else. Better off to fill with the urethane.  

[Noah]

If inexperienced, stay away from heat gun. Fraught with danger on veneer. If finish needs to be removed ise regular "strong" chemical paint stripper (wear gloves) and use bronze wool or chore girl pad and gentle careful use of paint scraper watch out not to gouge.

[anaisdog]

https://www.flickr.com/photos/10826951@N04/15630825311/in/photostream/
https://www.flickr.com/photos/10826951@N04/15634336642/


that is how they look.  i will try spraying with bleach and water, drying in the sun and then sanding, sealing all sides.  and no heat gun!

[Stu Jackson]

We did ours a few years ago with chemical stripper, no heat gun and little if any sanding.  Also used minwax urethane.  I agree, heat guns are for the pros.

[Noah]

I redid these in my garage 3-months ago. They were no where near as bad as yours however... Just sanding and 6 coats of matte wood finish turned out well. There was some sun faded color changed spots but I did not want to bother taking the base finish off to even out the color. It's a 1990 boat and has years of lovely "character" to show for itself!

[anaisdog]

wow!  they look great!  Stu, what kind of stripper did you use?

[lazybone]

Carefully examine the edge of the plywood to learn the thicknesses of the top veneer before sanding.
Be careful, it is very thin and it is easy to make a mess of things.

[Ron Hill]

Guys : Stripper maybe OK, just be careful that it doesn't dissolve the glue that holds the vainer to the plywood!!

A thought

[anaisdog]

i think i'm going to sand , with a much higher grit than i thought, and use a bleach mix.  and put poly on both sides.  thanks all

[KWKloeber]

i think i'm going to sand , with a much higher grit than i thought, and use a bleach mix.  and put poly on both sides.  thanks all

Suggest sealing the bottom side against moisture using the West Systems with clear hardener.  I do that on the backside of teak access doors or anywhere else I need protect or make it easy to clean and isn't subject to UV.  Much quicker than waiting for multiple coats of varnish to dry.

Ken k

[anaisdog]

like the 150 epoxy, Ken?

[KWKloeber]

like the 150 epoxy, Ken?

Actually I like Maas resin better, but that doesn't matter -- just the clear West 207 hardener instead of the stuff that's dark.
Or Mas resin with medium hardener, which is also clear. 
FYI, you can use west hardeners with Mas resin at the same ratio you would use with west resin.  The hardener determines the ratio, not the resin.

If they were real bad (deteriorating, not stained) you could use the low-viscosity mas penetrating epoxy.

Ken