sand blasting speed

[fractal]

Let's hope this isn't too far off topic..

Can anyone give me a hint how long it should take to strip the paint off a small metal outside table? I picked up a basic sand blaster kit at the local hardware store to strip a small 2x3 ft table and have been amazed how long it is taking. I have been told to run the air pressure as high as it will go and picked up a bag of 60 grit sand. A half an hour later and a half sack of sand and I have stripped maybe 20% of the table.

Is this typical for sand blasting or am I doing somthing wrong?

 

[Ozarker]

Your question is just about impossible to answer. How long it will take and how much sand it will take depends on a number of factors. Size of the table, how much decorative detail it has, how many coats of old paint are being removed. There is just no way to tell.

I have a small sand blasting gun with a tube attached that you drop into a bag of sand or other media to siphon it out. Last time I used it was to take the paint and rust off of a set of wheels for a Chevy PU I am restoring. It took me about an hour per wheel and I don't remember how much sand I used. Of course I nailed together a quick plywood box to work in and recovered and reused a lot of the sand.

If I were doing outdoor furniture with a lot of paint on it, I would used paint stripper and a high pressure sprayer. Then I would use the sand blaster to clean up the final detail and rough up the surface for repainting.

 

[Anonymous Poster]

Sounds like you're using a suction type blaster, and somebody had some fun with you. Setting the air pressure as high as it will go sounds like you're running thru a regulator, which will cut back on aor volume.
Suction blasters operate best when the bucket is at the same height or hogher than what you are blasting, thereby eliminating the need for compressed air to lift the blast media.
If you go with decent blast media, anything above 60# of air should cut paint off. Running air pressure higher than you need is a waste of energy, and just beats up the underlieing metal.
Depending on the gun and orphice size, you also might be shooting too close to your work. Try backing away from the target to about 6" and see if you get a wider pattern.
How large is your air hose? Small diameter and long hoses kill air efficiency.

 

[s1120]

How big is the compresser? I had the same problem with my blaster. I had a tiny compresser, and it just did not have the omph to do it. Also, it is not the PSI you need, its the CFM.

 

[buppy69]

A pressurized sandblaster is the only way to go. You can get one for well under $100 at stores and flea markets that sell imported tools. It uses less pressure and volume because the air is hooked to the storage tank and not the gun. It pushes the sand, not pulls it.

Eugene

 

[wroughtn_harv]

When I blast which is often at times I borrow a bud's 185CFM diesel compressor.

BTW I spent about three hundred for the hood I use. I was told I'd need a separate five horsepower compressor just to feed the hood at a constant sixty to eighty psi. Instead I hooked up a spa blower and it works even better. I use a one inch hose from my high volume low pressure sprayer to feed the hood. I get fresh air without oil and it's not heated.

I still occasionally do some artsy stuff off the shop compressor. But using the big dawg makes all the difference in the world.

 

[fractal]

Ok, will try dropping it back to 60 psi and vary my distance from the table. I guess I just expected more.

I am using a suction unit with the pail higher than the gun, running 50 ft of 3/8 hose from a 5.5 hp single stage compressor. I think it is rated at about 6cfm at 90psi. I am planning on hauling the compressor closer to the door and trying with a 25 ft hose to see if that helps. I did pick up a tank (presurized) unit off harborfreight and will give it a try too if this doesn't work better.

I wanted to avoid using chemicals and my yard doesn't mind the sand, so figured blasting it was the most ecologically sound way to remove the latex from the outdoor furnature.

Thanks for all the hints.

 

[Ozarker]

I can certainly understand why you wouldn't want to use chemicals but there is a new biodegradable paint stripper on the market called <A target="_blank" HREF=http://www.healthyhomeservices.ca/product.cfm?Room=Renovations&ProductID=81>Citristrip.</A>

 

[fractal]

Well, figured I would update my progress. I probably should have changed one thing at a time but ... well .... I didn't.

I switched from a suction type blaster at the end of 50 ft of 3/8 hose to a pressure pot blaster at the end of 30ft of 1/2 inch hose and changed from using whatever sand OSH sold me to some 30 mesh sand from the construction yard. I still have a standard ahrdware store 1/4 quick release on the compressor but am running larger quick releases on the other end of the hose and on the pot that I bought from the shop that made me the hose. Air volume to the blaster is no longer an issue (if it even was in the first place).

It works MUCH BETTER. It now removes paint where I point the nozle WHEN I point the nozle at the object. I no longer have to hold the nozle over the same location for 10-20 seconds to get it to take the paint off.

I am now to the point that any issues I am having are easily attributable to skill and not on the equipment. I have been experimenting with different pressures and so far 80 psi seems to cut the fastest although it does generate one problem -- the 5.5 hp craftsman compressor with a 25 gallon tank can't really keep up now that I got the right size hose to move the volume of air to the blaster. I now know how people with 20% duty cycle welders must feel.

 

[Anonymous Poster]

Couple improvements you can make,
First is to use a blasting media called Black Beauty. It will give you at least twice the bang for your buck in terms of cutting sand will.
The second thing you can do is add a portable tank, such as an old 100# propane tank close to your sandblaster. It will take longer to pump up both tanks, but it will also give you longer blating time.

Since you don't say what size tip you are using on the pressure pot, with your compressor and project, try a tip with a 1/8 opening.