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Author Topic:   Revarnishing mahogany what grit sand paper is best?
reeltime2 posted 08-18-2000 03:58 PM ET (US)   Profile for reeltime2   Send Email to reeltime2  
I am planing on varnishing all the wood in my 15 ft s.s. I striped off all the old varnish about 4 months ago and left the wood unfinished. Im ready to varnish this week end.

What grit sand paper should I use to prep for the first coat?

Should I sand between coats of varnish? If so what grit should I use there?

Also im going to buy a power sander to make the job go easier should I go with a random orbital, palm vibrating, or belt?

Thanks in advance,

Peter posted 08-18-2000 04:31 PM ET (US)     Profile for Peter  Send Email to Peter     
If all the varnish is removed, then you can probably use 150 grit paper with a palm vibrating sander for a light sanding. Make sure you move the sander with the grain of the wood. You may want to go over the wood again with a higher grit paper. After you've completed your sanding, blow all the sand dust off and then go over the wood with several sticky tack cloths. You may want to seal the grain with a grain sealer and stain (if you desire a color other than the natural color) prior to applying varnish. The first coat of varnish should be thinned a little with an appropriate solvent thinner. Definately lightly and throughly sand in between coats to roughen the surface to insure good adhesion between coats. You can probably use a fine grit sand paper 150 grit or above. Do not over apply the varnish in each coat otherwise when it dries it might alligator (also believed to be caused by inadequate sanding between coats). Apply the varnish evenly and resist brushing it too much and going over places where it has already been applied if you see a holiday. You'll get the holidays on the next coat and after a number of coats, it will all level out. Three to four coats should give you a nice, smooth, durable finish. Make sure you use a good quality captains varnish with UV filters and a good quality chinese bristle brush. These things may cost a little more, but if you use these things and take your time, your results will be visually well worth it. Also, let each coat dry at least 12 - 18 hours or more. I recommend letting each coat dry 24 hours.

russellbailey posted 08-18-2000 04:33 PM ET (US)     Profile for russellbailey  Send Email to russellbailey     
Use about 100 grit for your last sanding before your first coat of finish.

Use 150-220 grit after the first coat to knock off the raised grain.

Use 220 lightly after each successive coat.

I put about 5 coats of spar polyurethane on a 60" x 12" bench for working out (sweat and all, so I wanted a tough finish). For this, I wet-sanded up to 1000 grit to give it a deep, very smooth finish. Neat look.

I recommend a 1/4 sheet random orbit sander. I even used this for wet sanding (carefully).

lhg posted 08-18-2000 06:54 PM ET (US)     Profile for lhg    
Adding to all the good advice above, be SURE to sand the wood down to it's original reddish brown color throughout. Just removing the old varnish isn't enough, as every Whaler I have ever seen in need of varnish refinishing, always has bleached out (yellowed) mahogany underneath the old varnish. The sun damaged surface wood fibers need to be removed (sanded) from the surface first.

I would also recommend that you wipe on a coat of mahogany stain before you varnish.
This will give a nice dark finished color, which will keep it looking better, longer, and protect the wood from ultra-violet degradation.

David Reid posted 08-19-2000 07:55 PM ET (US)     Profile for David Reid  Send Email to David Reid     
see the entry last updated 8/9/00 on "best finish for teak". Lots of good commentary on refinishing in general.
reeltime2 posted 08-21-2000 10:26 AM ET (US)     Profile for reeltime2  Send Email to reeltime2     
Ok I dident get to start this weekend but will do it this week end. I think I need to use a sanding sealer because the grain is so open on the wood. Is this the corect order?

1) prep wood (sand)
2) apply stain
3) apply sanding sealer
4) more sanding
5) first coat of varnish
6) fine sanding between coats
7) another coat and so on
Im not sure if the sanding sealer comes first or the stain.

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