As if I weren't abrasive enough...

March 22, 2012 5:00 PM

I need to rent (or acquire, if renting is silly) a sandblaster, as well as the correct abrasive material to sandblast the interior of a 22' fiberglass sailboat. I have access to a large air compressor, and I'm handy with tools - just never used a sandblaster before.

The interior of the boat has been painted several times, and I'd like to take everything down to the bare fiberglass, dewax, prime, and repaint.

What do I need? What do I need to know? Any idea how much of the correct abrasive material I might need?

(the boat is a 1970 Macgregor Venture 22, identical to this, if you're curious).

posted by namewithoutwords to grab bag (8 answers total)

Bicarbinate Soda is what the SO uses in place of sand, he works in boat maintenance. It's just the right grit to remove paint and not harm the fiber glass.
posted by misspat at 6:27 PM on March 22, 2012

You can buy soda in 50lb bags expressly for blasting, both in coarse and fine (Harbor Freight). I use it to blast engine case's. Sears sells a simple blasting rig. This works fine for occasional use. And the soda just dissolves harmlessly away.
posted by Pecantree at 7:03 PM on March 22, 2012

Not an expert, just have been interested in sandblasting for my own purposes and have been researching.

Harbor Freight (if you have those nearby) has sandblasters that will do the job for ~$120 - $200. Rental for larger ones would cost about $80 a day (depending upon your location).
I'd prefer a smaller one that takes a little more time but that I own. You may think differently.

Medium is cheap at HF.

Soda is cheap too, but a rig will cost you more because they require line dryers (compressing air causes condensation, soda is hygroscopic and will clump, clogging lines etc.). My buddy who uses blasters in his line of work has not been impressed by any line dryer he has ever used and sticks with sand or nut shells as his medium.

Sorry, I have no idea about correct medium for fiberglass. Not my target, so it's been outside the bounds of my discussions and research.
posted by Seamus at 9:32 PM on March 22, 2012

You need to know that sandblasting is extremely dirty work. You need a hood or some sort of protection. You need a respirator or mask for dust too. I've only sandblasted small parts. Without an enclosure the medium gets everywhere. Sandblasting the inside of a fiberglass boat sounds like hell. I wish you the best of luck.
posted by bdc34 at 7:25 AM on March 23, 2012

May I suggest that instead of 'blasting' you use the correct type of paint stripper/remover?
If 2 part epoxy paint was previously used this is probably not a good idea.
However try some research using Google or your local West Marine.
posted by lungtaworld at 9:16 AM on March 23, 2012

lungtaworld: "May I suggest that instead of 'blasting' you use the correct type of paint stripper/remover? "

The problem here is twofold: there are many hard-to-reach places, and the boat interior was incorrectly painted at least twice, using housepaint.

So unless I miss my mark, sandblasting (or sodablasting) is going to be more effective and much less effort than trying to strip the interior chemically. (I'm working under the assumption that spraying chemical paint remover is a REALLY BAD IDEA without hardcore protection). Plus from the comments others have made, sodablasting is going to be much easier to clean up than chemically stripping.
posted by namewithoutwords at 9:54 AM on March 23, 2012

Don't kid yourself - most abrasive blasting is terrible stuff; for example, here is what the CDC says: abrasive blasting dusts are a very great health risk if the process is not completely isolated from the operator. And if the paint contains lead that is a completely new level of hazard.

My novice understanding is that you should use plastic bead blasting on fiberglass.
posted by zenon at 1:42 PM on March 23, 2012

seconding that sandblasting, particularly on fiberglas, is deadly toxic and requires a bunch of really expensive, specialized fan and venting equipment, not just a sandblaster. I would seriously, seriously, SERIOUSLY consider having it professionally done, even if the cost is (and it's likely to be) much greater than doing it yourself. spending a few hundred more bucks really IS worth it when you consider that you might be increasing your risk of lung cancer by a factor of 1000.
posted by sexyrobot at 2:48 PM on March 23, 2012