Wet Sanding

[tartansailor]

Greetings,
We are planning to wet sand, compound, polish and wax over the winter, and I was wondering if someone could recommend a good "wet sander" to take the drudgery out of this task?
I hope its not the hand sander regimen.

Dick

[Marc Theriault]

Dick,

I use an air sander. I bought a compressor and a sander. My compressor is a 3 hp. I know it's not enough, everybody told me that, but i use the sander at a small speed with a #80 grid.

My method is like that:
I use a garden hose with a small flow of water just above where i sand don't use too uch speed for the sander because you will splash water and old paint every where.

I actually doing it for the antifouling and it's working great. I don't expect that the compressor will survive the job but again if i had made sandblasted the hull it had cost me a lot more than the compressor.

Marc

[Wayne Grenier]

You do not! want to use a power sander on the hull of your boat!1st thing is-if its electric and you try to wet sand with it you'll get electrocuted-2nd you'll burn through your gel coat-(but that won't matter-see #1)there a hundreds of entries on this board about different techniques to bring your gel coat back to life-I am in agreement with the general consensus-(my boat is a 1974 and the hull is still original gelcoat-so take it from me)-wet sand the worst stains and oxidation BY HAND-keeping the surface wet and using progressively finer sand paper-say from 400 grit for the real bad stuff up to 1200 or 1500 grit-then compound-polish and wax-there is no easy way to do this-you can put 4 hrs in or 40 hrs-its up to you-but its the exact same technique and materials you would use if you were doing a car! go to a local auto body paint supplier for the 3 m machine finishing compound and lambs wool wheel-you can use a buffer/grinder for the polishing and compounding-the Cape Dories have "extra thick" gel coat and are ideal candidates for gel coat restoration-plus the 1st time is the hardest-when you have to remove years of oxidation-

[Oswego John]

Wayne,

Well said. You beat me to it, saying about the same advice.

Don't sand gel coat. It will ruin the finish. I only wet sand repairs to gelcoat. No electricity used on wet sanding. I use a semi-flexible 3M rubber hand sander. And it's variable speed, too.

I use mild compound for bringing the finish back. As for protective waxing, I'm a believer in the old adage,"The harder it goes on, the harder it comes off. The easier it goes on, the easier it comes off,"

For as long as I can remember, I used DuPont #7 compound applied by hand. When the powdered oxidation was towel rubbed off, I applied Simonize paste wax by hand and then hand rubbed it to a brilliant looking glass finish. Sometimes, I used Blue Coral or other carnauba paste wax.

Forget using the whiz bang, super duper, three minute, miracle spray on junk that's on the market.

If a hull is done properly, next year, all you have to do is rebuff it. If you are not careful when power buffing wax, you can produce halos and rings in the finish. Go easy, don't produce heat on the finish.

A well protected hull will resist oxidation, waterline yellowing and exhaust smudging on the transom.

That's my 2¢ FWIW
O J

[Marc Theriault]

wayne, Oswego,

I did not pay enough attention about what Dick want. You're right for the job he want to do, a sander will be too hard on the gelcoat.

In my case, i want to apply a barrier coat and i need to remove 30 years of antifouling without doing too much dust so i tought about it and i tried my idea, it's working really fast because the grid of the paper stay always neat.

My excuse Dick, Wayne and Oswego give you goods advise.

Marc

[Oswego John]

Hi Marc,

No need to say sorry. No problem. It is nothing.

I like the idea of sanding with air. It will surely cut down on the copper bottom paint dust. And you don't have to worry about electric shock.

After I read your post about using an air sander, I looked them up in some of my tool catalogues. I saw a pretty nice one in the Harbor Freight catalogue.

http://www.harborfreight.com

It's catalogue item # is 93050-1CGH

This wet sander has a built in, adjustable water supply for continuous operation.

Good luck. Don't forget to wear a mask.

O J

[Oswego John]

On second thought, after reading about the wet sander I previously mentioned, maybe it isn't suitable for sanding anti-foul paint.

I now see that it is for granite and other stone and the sanding pads are coarse and medium. I don't know, now.

O J

[tartansailor]

Marc, Wayne, John;

Sincere thanks for all of your valuable input. I feared as much, but you are right, it is the only way to go.

The previous owner(s) left so much paint on the bottom; and whoever repainted the hull missed something, for it all alligatored.
It took 3 full days with a razor scraper to remove just that.

Am planning to take the bottom down to its gel coat and hope there are no blisters.

Again, thanks for the reality check.

Dick

[Ron M.]

My boat also came with 25 coats of bottom paint. I hate sanding/grinding, especially that stuff. With a variety of chisel blade scrapers/wood chisels I got 90% of that paint off with about 3 days of effort.I broke the time up and worked other projects to break the tedium. A lot less dust and the chips were vaccumed up.
________
CHRYSLER PHOENIX ENGINE SPECIFICATIONS

[chase]

When I first read Dick's posting, I thought we were talking gelcoat restore on topsides and there were various responses to that. Then on to crusty bottoms, hence my confusion.

Consensus is no sanding (on gelcoat) except in extreme cases but use compounding products? There is an article in a past Cruising World about restoring gelcoat and they in fact recommend wet sanding. Having no experience with this, I’m in no position to comment with any authority. Since I'm planning to haul in October for bottom paint and topside restoration I'd like to clarify.

A rubbing compound or gelcoat restorer uses very fine grit in suspension to basically sand the rough oxidized surface off, right? So what's the difference? Why not use a very fine grit sandpaper and wetsand? I was encouraged by an older more experienced sailor to use a 3M product and my electric buffer to do the job and then wax. That is what I'll do, I just aint got the time to hand sand my hull unless one of you convinces me it is worth the extra effort.

Now on to the bottom paint. Why bother taking a bunch of layers of ablative paint off the bottom? Isn't it just more protection? I just planned on scuffing and hitting the thin, turbulent spots with more coats, two more total coats and splash. I'm sure there must be some huge emotional payoff to stripping a hull, but what about other benefits? Tenth of a knot? Bah Humbug in a Tyvek suit.

I do have one more question about order. Since I also want to paint the bootstripe, should I do that AFTER the final wax coat? I’m afraid that waxing over a bootstripe painted 24-48 hours prior may spread red paint everywhere.

I realize there may be more info on this in the archives, but since the conversation has started......

[S/V Necessity]

Well I cant exactly figure out if it's being sanded or scraped or if it's the bottom or the top..... But to answer what I think was the origional question. I would give a Dynabrade air sander and Abralon foam backed hook loop pads made by Mirka a try. I have wet sanded *alot* of finish and this has worked better than anything else I ever tried. I used 500 grit to remove material, and 1000-2000 to prep for buffing or recoat. Never did use the 4000 for much. The pads cut quickly, but do wear out after 5 full minutes, perhaps might last 10-15. But when they do "seem" to wear out, throw them away. Your time has to be worth something, and I promise you when they quit cutting, they quit. They are expensive so the temptation is to use them way longer than you should.

I can NOT honestly say I've ever used it on gel coat though. Automotive finish and furniture laquer yes. So if one was dead set on doing some wet finish sanding, this would be my reccomendation. And I think that was the origional question.

For what it's worth I personally have alot better control with this setup than with the buffer. I would use the foam backed pads for most everything and then very often hand buff when I was done sanding. I have no idea if this would work with a gel coat. Different materials do work/handle differently. It could just be me, but It's REAL easy to burn through a finish with an automotive buffer and buffing compound. Just cause it's a creamy paste doesnt mean you cant eat right through the finish with it! I tried to avoid the buffer if at all possible (I was finishing grand pianos, and dining tables though) If you are worried about removing too much material with 500-1000 grit wet dry paper, you should be worried if you are using an automotive buffer also. However sometimes the buffer is the tool that's needed. sigh....

That being said I'm not about to reccomend to sand or not, I simply dont have enough fire protection for that Also I would always try the least agressive approach first anyways.

[Oswego John]

When I first read Dick's posting, I thought we were talking gelcoat restore on topsides and there were various responses to that. Then on to crusty bottoms, hence my confusion.

Farmer Chase, (I'll use the initials FC for your quotes) (OJ for mine)

OJ:
Let us pick this thread apart and see if we can get some semblance of order out of it. At least the way I look at it.

Yes, you are correct. Dick was talking about wet sanding his hull above the waterline. Marc misconstrued the idea and mentioned that he used an air powered tool to wet sand his bottom.

Wayne correctly advised Dick to not use an electric powered sander to wet sand his hull. I basically repeated what Wayne said.

At this point, I should mention that there is a difference between sandpaper (whether it is garnet, aluminum oxide, silica or any other type of grit medium) and wet-n-dry abrasive sheets for wet sanding.

When sandpaper becomes wet, the glue binding the abrasive to the paper dissolves and it is impossible to use. Therefore, it should be kept dry and only used on dry surfaces.

Wet-n-dry has no problem being wet. It is designed for wet sanding.

Dry sandpaper is usually used, depending on the coarseness or fineness, for wood, fibreglass, epoxy/poly and removing rust, etc. Wet-n-dry can be used dry, but it is generally used wet, not for stock removal, but to remove minute flaws and finish prep for painting or other treatment, such as compounding or waxing.

FC:
Consensus is no sanding (on gelcoat) except in extreme cases but use compounding products? There is an article in a past Cruising World about restoring gelcoat and they in fact recommend wet sanding.

OJ:
They recommend *WET SANDING*, not sanding with dry sandpaper.

I think that some of the confusion may be that Wayne and I mentioned to Dick to not use dry sandpaper on gel coat and also warned not to use electrical power while wet sanding. At this point, Marc brought up the air powered wet sander for his bottom paint removal. I think that Wayne was warning of the danger of burning through the gelcoat by accident, and I agree.

FC:
A rubbing compound or gelcoat restorer uses very fine grit in suspension to basically sand the rough oxidized surface off, right?

O J: Agreed. On small jobs, I have often used toothpaste.

FC:
So what's the difference? Why not use a very fine grit sandpaper and wetsand?

OJ:
Wet sand with what, your buffer, electric drill?

FC I was encouraged by an older more experienced sailor to use a 3M product and my electric buffer to do the job and then wax.

OJ:
So what's the difference, you ask? You can't wet sand with very fine grit sandpaper. It will turn to mush. If you are going to wet sand, you have to us wet-n-dry.

It's not for me to say, but if I were you, I would take this older, more experienced sailor's advice with a grain of salt. The way I read it, he encourages you to stand on the damp ground and power buff with your electric buffer. Better to read Wayne's post again.

FC: That is what I'll do, I just aint got the time to hand sand my hull unless one of you convinces me it is worth the extra effort.

OJ:
We just don't want to see anyone electrocuted because he ain't got the time to work in a safe manner. Remember, you have a family who loves you.

FC:
Now on to the bottom paint. Why bother taking a bunch of layers of ablative paint off the bottom? Isn't it just more protection? I just planned on scuffing and hitting the thin, turbulent spots with more coats, two more total coats and splash. I'm sure there must be some huge emotional payoff to stripping a hull, but what about other benefits? Tenth of a knot? Bah Humbug in a Tyvek suit.

I do have one more question about order. Since I also want to paint the bootstripe, should I do that AFTER the final wax coat? I’m afraid that waxing over a bootstripe painted 24-48 hours prior may spread red paint everywhere.

OJ:
I don't advise you to wax first and then paint.

Chase, please don't think these ideas are expressed in any caustic manner. Wayne, I and the rest are concerned with your wellbeing and safety. Good luck. O J

FC:
I realize there may be more info on this in the archives, but since the conversation has started......

[/b]

[Wayne Grenier]

If anyone would like a free lesson in how to scrape and sand the bottom paint of a boat and wet sand and compound and wax the hull please show up at my house in early May and I'll be glad to show you!! I'll even supply the materials and beer! (somehow I don't think I am going to get any takers on this one-but it worked for Tom Sawyer!)

[chase]

OJ,

Thanks for taking the time to break that down -- whew! When I mention sand in my post, I was thinking about the wet stuff, "gator" something is what I've seen at the hardware store. I've never seen it for a random orbital.

I appreciate the reminder about electrocution, but I did stop short of running the Ryobi from the dinghy to spruce the topsides up. I wont say I wasn't tempted, but I'm hauling out next month.

In optimal conditions (dry ground, plenty of cold beer, beautiful women fanning me while I work), why not use the buffer? I read halos from heat and others caution the aggressive nature of these buffers. So, do I read that applying compound by hand is the way to go? Same with wax? Sorry, I'm not ready to let go of the idea of using a machine to do this job. It aint cause I'm lazy (not quite true)) or cavalier about the dangers of electrocution, but because I've got to get a lot done over a few days and get the boat off the hard because it is expensive.

What I'm trying to do is package this process in my mind and get set to do it in October. I'm looking for a balance of efficiency and adding long-term value/ beauty to the boat.

As far as the boot stripe goes, how long do you reckon I have to wait to wax over the stripe after painting? Should I just skip the wax on the fresh bootstripe? I agree painting over wax does not make much sense.

Is there a good book for this stuff? This Old Boat or something like that?

Best,

Chase

P.S. What In the world makes you think I’m so sensitive? I suspect that you are way more than twice as old as me and therefore have my ear whenever you opine. Your insights are always appreciated. Guess how many people in my daily life I can have these conversations with???? No the cattle and hogs don’t count. That said, we all must remember the limitations of this type of exchange. No visual or immediate feedback to add flow to a conversation, tone of voice, sarcasm, etc… As always, I read your posts with interest and look forward to more. That goes for all of you.

[Oswego John]

Chase,

Now yer talking. What i might do if'n I was in your shoes (boots?) is give the hull a good washdown using BoatZoap or other similar boat cleaner. and a medium soft bristle brush.

Look for stains, smudges and other discolorations and remove them with a cleaner specifically made for that purpose. Rinse well.

If the hull has any oxidized surface, apply light compound either by hand or with a buffer on low speed. Warning. If that buffer isn't on low, centrifugal force will throw the compound all over the place and into the next county.

Power buff the hull. I do this all the time. Just dont do it on wet ground. Here's a little tip. Did you ever hear of "spit shine?" We used to have our boondockers so you could see your face in them. What you do is spit on the leather before the final buff.

You can do that too with compound and wax. Your hull is too big for spitting on it so do what we do and dip a 1/2" or 3/4" paint brush in water and spritz it on the gel coat. You'll probably have to wear a dark pair of shades while staring at the newfound brilliance of the hull.

Okay, I might as well go a little farther. If you plan to hold that buffer at arms length all day long, every 1/2 hour it gets a pound heavier. By the time you get finished compounding and then waxing the hull, you'll have arm muscles like Popeye.

What some people do is install a 2x4 or other support above where they are working. They support the buffer with a screen door spring attached to a cord, attached to the 2x4. Others hang a sheave (pulley) to the 2x4. If the buffer weighs 4 pounds, they attach a 3 pound weight to the other end of the cord that passes through the sheave and to the buffer to counterbalance the buffer some. The 2x4 has to be movable as you proceed along the hull.

Make sure that you plug the buffer into a ground fault outlet.

Good luck.
Rube Goldberg rules!
O J