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Old 25-08-2011, 21:28   #1
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Sand Blast Questions

I read that some CF’ers have grit blasted their boats including the inside. I have a 40’ steelie and want to do a bit of cleaning up of rust here and there, inside and on the deck.

I found some mobile blasting tanks on ebay. Capacity range varies but 5, 10 and 20 gallon tanks are affordable. They have pressure regulator / gauge, hose and spare tips. Just need to supply the abrasive and a compressor. There is even a small 1 kg version (SANDBLASTING GUN SANDBLASTER POT & NOZZLE SANDBLAST | eBay).

Just wondering what spec’s people would recommend, what size grit tank, what type of abrasive. Is a small unit better for containing the mess? Also, what type of personal protection and what type of barriers do people use – would canvas or cardboard suffice?

Any advice appreciated.

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Old 25-08-2011, 22:56   #2
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Re: Sand Blast Questions

Not sure about Oz but over here there are a lot of restrictions with sand blasting.

Here we're required to put up a tent to contain dust and with a vacuum pump to collect the dust. If your on private property away from population, you can get away without the tent as long as the PC people don't know.

Also the dust usually has to be sent to a hazmat facility. (lead in paint, stainless steel and all)

If your going to be in closed spaces you'll want a rubberized space suit especially designed for blasting. They have a hose attached from the compressor to feed you air and keep you cool.

The best type of blaster are the pressure pots, not the suction hose type. less clogs when reusing sand.

Depending on the condition of the metal will determine the type of abrasive. Metal beads for the heavy stuff and glass for fine work. I'd talk to your local supplier on what grades they have available.

Have you considered renting the equipment.

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Old 25-08-2011, 23:35   #3
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Re: Sand Blast Questions

thanks Del. I better check on regulations.
I had not seen this type of equipment for rent before, but the prices on ebay are not too bad and I like the idea of not having any time/cost pressures. Cheers
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Old 25-08-2011, 23:37   #4
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Do you really have to?

Were talking patches of rust inside the hull, right?

Why not remove as much as possible using conventional means (chip hammer, wire brush, phosphoric acid - some have mentioned a needle gun) then go with a top quality paint system (POR 15 or Ameron for example).

Its going to be slow and painful but compared with the incredible mess of abrasive blasting its got to be worth considering.
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Old 26-08-2011, 00:11   #5
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Re: Sand Blast Questions

Once you start blasting at rust spots there is a temptation to stray and do bigger patches. It takes on a religious tone and is theraputic, so ask yerself punk, are you prepared to do it all?

Apart from smaller jobs in a blast cabinet, ive only used gravity fed hopper systems with kiln dried coarse sand.
With the right nozzle and pressure, its enough to disolve porous metal, fingers etc and its cheap.

If your sand and air is dry, its a good way to go. Easier if you have a buddy to look after the gear while your in the suit. If the suit is pressure fed, make sure the compressor is sucking clean air too otherwise you wont be well for long. Even be aware you might be breathing air from a mouldy old tank. Bugs grow well in the warm wet dark tank.

As for dumping the waste after, I couldnt possibly comment about people who say nothing and just get on with it.
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Old 26-08-2011, 00:20   #6
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In Newcastle. Did hard to get at corners with a small gravity fed sandblaster bought on eBay. It doesn't matter what you do or how you cover yourself. It gets EVERYWHERE! Used garnet and vacuumed up after. Still picking up sand months later.
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Old 26-08-2011, 00:39   #7
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Re: Sand Blast Questions

I've got get my GRP bottom blasted and I've been advised to have a soda blast, more expensive but easier to clean up afterwards, and much more environment friendly. Don't know if it would work as well on steel, but I should think so.
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Old 26-08-2011, 07:08   #8
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Re: Sand Blast Questions

Has anybody tried dry ice blasting,and have an idea of costs???Ole
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Old 26-08-2011, 07:39   #9
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Re: Sand Blast Questions

What ever you decide to do, don't inhale the dust. A respirator of one kind or another is a must have. I used play ground sand. Its wet when you buy it, so pour it out and let it bake in the sun until its dry. You must have a clean air source for you and your compressor. If you dont wear a protective suit, you will get sand in cracks you didn't know you had..
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Old 26-08-2011, 17:22   #10
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Re: Sand Blast Questions

One thing about the cheap ebay blasters. Be sure you have a source for nozzles. Most of those cheap units have one nozzle, mild steel or even aluminum. Once you wear it out you will need another. I have two different hand units, one draws from a bucket, the other has a small hopper on top. Only for small jobs like rust in the deck after a ding. Ideally you want a large pressure tank, and a very large compressor. Most DIY store compressors are too lame as you need at least 10cfm at 90psi continuous. I scored a ridgid gas powered compressor which is marginally acceptable so that's what I'm using. It will live under the boat, the hose will go up through one of the holes where I pulled out a thru hull and away we go. Oh yeh, don't for get your space suit.
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Old 26-08-2011, 17:46   #11
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Re: Sand Blast Questions

Plain old silica sand is by far the cheapest. An air supply type mask is mandatory, don't even think of using a filter type rig. Inhaling silica is bad for your health, and you will be enveloped in it. The air supply mask will keep you safe.

As far as blasting rigs go, get a pressure pot, meaning the sand holding container is pressurized. The reason for this is that the sand exits at a significantly higher velocity from a pressure pot system and thus is more efficient. Harbor Freight has a variety of blasters for good prices. If you're only doing little spots you could buy a little one. To give you a frame of reference, with the little units you can expect to go thru 100 lbs of sand in about 15 minutes.

The bigger the compressor the better. Less than 10 CFM is going to be pretty slow. 20 is twice as good.

If you want to really do a good paint job you have to blast. Period. Blasting doesn't just remove rust and dirt, it also gives the steel a rough surface that the paint can really grab onto. Blast it to white metal, paint it right with severa; coats, not just a couple, and you will have an almost lifetime paint job.

Have fun, Paul
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Old 26-08-2011, 18:51   #12
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Re: Sand Blast Questions

Please never use sand for blasting or you will be a candidate for silicosis, a fatal lung disease. Use an approved blasting medium like garnet, granulated slag, ilmenite (sp?) or similar.
Regards, Richard
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Old 26-08-2011, 19:16   #13
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Re: Sand Blast Questions

I've done sand blasting (not actually sand, to be clear) in confined spaces (refinery equipment) and it is not for the faint hearted. The gear required is substantial.

* It is REALLY loud inside a tank or boat. Plugs inside earmuffs.
* It is really hard to see. The grit blocks all of the light and the dust does not dissipate as it does outside.
* Inside a boat the mess would be unbelievable. Not just sand, but all of the fines.
* The breathing air must be good quality. Common air compressors are not suitable.
* The air must feed either a proper respirator or blasting helmet.
* You need a helper to manage the sand. It's a bugger to keep it flowing in damp weather.
* Hotter than hell. After suiting up it is unimaginable and dangerous in warm weather unless you have a special cooling hose system. Its rather warm in cold weather.

And I left a bunch out. Real safety concerns. Real difficulties. I would contract the job out, and I'm pretty game.
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Old 26-08-2011, 19:21   #14
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Re: Sand Blast Questions

You might look at water blasting too. All of the big shipyards are doing that now

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