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rcx822
Joined: 31 Dec 2010 Posts: 112
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Posted: Fri Jan 01, 2016 9:00 am Post subject: Sandblasting outdoors safety |
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I've done a bit of Googling but I can't find any official or sanctioned information on this. I have some large parts to sand blast, which won't fit in a cabinet.
I think that media blasting outside using proper media (not sand) and a P3 mask is safe (I think) when it comes to lung problems. But is proper media too expensive to use outside where it's immediately lost? It's £1.80 per kilo at Machine Mart. Maybe if the media is bulk purchased then it's more reasonable.
With regular sharp sand, is there any way to use it safely? Or does that require a "forced ventilation" mask? And if so, then what does a forced ventilation mask run off? I've seen the mask itself costs £200, but then hose and something to connect it to is needed. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4100 Location: South Cheshire
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Posted: Fri Jan 01, 2016 12:12 pm Post subject: |
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I bought a 'pot' blaster thinking I would be able to tackle bigger jobs...there are a few challenges; it is slow work and creates a hell of a mess! If you can live with this, then there are a multitude of different sorts of media depending on how aggressively you want to blast, normaly sold in 25kg sacks and far cheaper than MM. There is no need for an air fed mask as the media is not toxic.
In the end I gave up using the pot blaster and take panels down to a local firm, who charge about £30 to blast a wing and from memory £100 to blast a Morris 8 SE chassis. They use a huge desiel driven compressor and work in a sealed room where the media can be swept up and reused.
If you do use sand or any other media for that matter, it must be bone dry, otherwise you will spend more time unblocking the gun than actual blasting!
Cheers
Dave
Last edited by ukdave2002 on Fri Jan 01, 2016 12:32 pm; edited 1 time in total |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1733 Location: Above the snow line in old Monmouthshire
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Posted: Fri Jan 01, 2016 12:29 pm Post subject: |
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I've done a fair bit of outdoor blasting using ordinary building sand dried in an equally ordinary gas oven... I reckon you're safe enough with a fairly basic mask (and goggles), the trick is to choose a good breezy day and make sure you stand upwind of the work. You do need a hell of a lot more media (of whatever type) than you would think though, so it's best to get off as much as you can using wire brushes or chemical treatments first. Open blasting, to my mind, is very much a last resort. |
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Rick Site Admin
Joined: 27 Apr 2005 Posts: 22429 Location: UK
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Fri Jan 01, 2016 9:50 pm Post subject: |
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My experience matches those who've already commented. In my case it was just a matter of doing the parts of four brake drums where the rotary wire brushes on the grinder wouldn't reach. Couldn't believe how fast it chewed through the grit, or how much of it rebounded and hit me in the face, so a decent pair of safety glasses is essential. It's extremely wasteful and frankly impractical (and uneconomic) for all but the occasional small job.
Richard |
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Da Tow'd
Joined: 16 Jun 2010 Posts: 349 Location: Bella Coma British Columbia Canada
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Posted: Sat Jan 02, 2016 5:40 am Post subject: |
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I bought a stinky "cat sprayed" huge 6 man Nylon tent at a garage sale for $10.
When I use it we hang it from my overhead beam in my shop and with the screen door and "windows" the air comes out but the sand stays in . I bought a well used diesel jack hammer air compressor from a tool rental place . So I have plenty of air.
It is big enough to get anything through the zippered door.
It doesn't smell like cat pee anymore.
I bought a few bags of fine sand blasting sand and ground up walnut shells.
Strain the big chunks and reuse.
Hank |
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rcx822
Joined: 31 Dec 2010 Posts: 112
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Posted: Sat Jan 02, 2016 5:17 pm Post subject: |
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I tried the tent technique but the tent just ballooned up. Maybe bigger tent and big vents are needed.
So maybe the way to go is tent, safe blasting media, and a P3 mask? P3 mask is one of the higher grade dust masks, that uses decent filters and rubber seal to your face.
Appreciate people are getting their bits professionally sand blasted, though the local places here have minimum charge. But they will also zinc plate parts within the £60 minimum charge which is good. |
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kevin2306
Joined: 01 Jul 2013 Posts: 1359 Location: nr Llangollen, north wales
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michael1703
Joined: 22 Jul 2009 Posts: 349 Location: suffolk
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Posted: Sat Jan 02, 2016 6:35 pm Post subject: |
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I've got a blasting cabinet and used kiln dried sand and found that my blasted parts rusted very quickly
The moisture in the sand gets into the work piece
I've found garnet is good for heavily rusted items, I got mine from scangrit
http://www.scangrit.co.uk |
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Kenham
Joined: 12 Mar 2012 Posts: 209 Location: Kent
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Posted: Sun Jan 03, 2016 5:12 pm Post subject: |
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It is usually the moisture in the compressed air that causes the rusting so try cooling the air (I use steel pipe through a tank of water} then through a moisture trap to extract the water. The harder the compressor works the hotter the air gets and makes more moisture. I usually blast things outside on a big sheet so you can reuse the sand two or three times, usually cuts better the second time. Don't ever use a sand blaster without the proper air fed helmet, you will regret it later. You only have two eyes and one face you really need to keep them. I have seen someone blast their hand , not a pretty sight, from skin to bone in a fraction of a second. When the sand leaves the nozzle it is going quickly , its still going quickly when it comes back at you, safety goggles and glasses will be as much good as an ashtray on a motorcycle. Ken |
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rcx822
Joined: 31 Dec 2010 Posts: 112
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Posted: Sun Jan 03, 2016 5:14 pm Post subject: |
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Kenham, the big sheet is also a good idea. I wanted to sandblast some bits "in situ" on my car so that solves that.
With air fed masks, the masks themselves are £200. But I haven't yet looked at what they need to connect to on the other end and what costs are involved on that end. |
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MikeEdwards
Joined: 25 May 2011 Posts: 2463 Location: South Cheshire
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Posted: Sun Jan 03, 2016 8:20 pm Post subject: |
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I've been using a large plastic bag with some success - stick a door or something like it in the bag, hands in the bag, pegs to hold the end reasonably closed, and blast by feel with regular checks to see you're in the right place. I use silica-free glass grit that I got from eBay.
I'm having some trouble with it at the moment, but not related to the bag. It's a big bag that a mate got a hardtop in. I use a fairly basic mask, but because the grit is all kept inside the bag there's virtually no media or rusty dust escaping. Originally I had a pipe as a vent / exhaust into a bucket, but there's enough small holes in the bag now that it doesn't inflate. |
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D4B
Joined: 28 Dec 2010 Posts: 2083 Location: Hampshire UK
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Mon Jan 04, 2016 10:34 pm Post subject: |
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There's also soda blasting, of course (bicarbonate of soda). My guess is that a lot of grunt is needed for these media to be effective, and that for the relatively modest capabilities of most home equipment more abrasive materials such as sand and garnet would give a better and faster result.
Richard |
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Kenham
Joined: 12 Mar 2012 Posts: 209 Location: Kent
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Posted: Mon Jan 04, 2016 11:11 pm Post subject: |
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Yes the air fed helmets are not cheap but a lot cheaper than plastic surgery or silicosis. I picked all my kit up second hand you just have to keep looking.The helmet is air fed from the compressor via a filter, a friend of mine uses a small electric compressor just to feed the helmet to get maximum from his main compressor, make sure if the compressor is engine powered that fumes do not enter the air intake. Even at a couple of hundred pounds it would not take many trips to a blasting firm to say goodbye to that much money. Ask at a local firm if they have an old helmet going cheap perhaps. My compressor is a big four cylinder diesel thing but even that won't run the blast pot at maximum cfm , its hard and expensive work to make a lot of compressed air even though the main ingredient is free!
ken |
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