Sand blasting

[Gregor 4,847]

Teach me about sand blasting media. When it comes to media, is it the same as sand paper ? The higher the number, the finer it is? I have tried to research this on line, but can't seem to find a definitive answer.  I have had a lot of Lawn Boy mower decks sand blasted. They always come vack super clean, not a spec of paint left on the. My blaster won't touch the paint, won't faze it at all. I don't know if that means the paint is really hard, or really soft.   Also, what is the coarsest grit available? As far as material, what is the most aggressive? Glass? Coal slag? Silica sand?

 

Thanks   Greg

[Achto 27,919]

In my blasting cabinet I use a medium grit coal slag.

https://www.tractorsupply.com/tsc/product/black-diamond-medium-blasting-abrasives?cm_vc=-10005

 

Silica sand is not recommended as there can be health issues linked to it. That being said, I do use silica sand in my pressure pot blaster for larger parts. This is used out side only and I wear breathing PPE.

 

 Both hard & soft paint can be difficult to blast, soft is more difficult in my opinion. A soft paint will absorb the shock from the media, causing it to bounce off instead of break through. In a few cases soft paint will kind of roll up in front of the media, kind of like blasting grease. Hard paint may be difficult to break through initially but once you do it usually peals off pretty well if you keep working from the clean edge of it. In either case the thicker the paint, the harder it blasts.

 

Good air pressure and a good blasting tip are key to blasting. If your tip gets warn out you are not concentrating your media enough to work well, plus you go through more air faster. Same effect as trying to wash dirt off with your water hose nozzle set to fan pattern instead of a stream pattern.     

Edited September 14, 2022 by Achto

[rmaynard 15,735]

I have a Harbor Freight floor-type blaster cabinet that I have made extensive modifications to. I use glass beads. They are marked 30-60, but I'm not sure how it compares in size to the TSC Black Diamond fine coal slag which I find quite coarse. These glass beads seem to work well on everything and it's cheap. Again, successful blasting depends on many things, pressure, volume, tip size, etc. What you are blasting is important. Soft paint is harder to remove than hard paint. 

 

 

 

[953 nut 56,187]

I also use glass beads in the blast cabinet but nearly everything that goes in there is needle gunned first, especially painted items. The time it takes to needle gun painter items will save you five times that amount of time in blasting and your blast media will last longer because it is not being contaminated with paint chips. Removes paint, rust and welding slag.

 

[squonk 41,649]

https://www.tptools.com/Most-Popular-Abrasives.html

[ri702bill 8,564]

Regardless ot the media you use - you need a good large capacity air compressor AND dry air and media. Moisture in either yields poor performance.

Bill

[rmaynard 15,735]

27 minutes ago, ri702bill said:

...you need a good large capacity air compressor...

 

You are 100% right Bill. I use a 60 gallon, two-stage compressor. The label says 11 CFM @ 90 PSI, but it's hard-pressed to even maintain about 7 CFM at 50 PSI. It runs constantly. 

[squonk 41,649]

I noticed the "Horror Fright" sandblaster cabinets use a cheap gun and large ceramic nozzles. The TP gun I had in my old cabinet had smaller nozzles, a replaceable orifice and used less air for the same result than the HF cab I had. 

[lynnmor 7,388]

3 hours ago, Gregor said:

Teach me about sand blasting media. When it comes to media, is it the same as sand paper ? The higher the number, the finer it is? I have tried to research this on line, but can't seem to find a definitive answer. and?

 

 

This chart should answer your question about size.

[pfrederi 18,004]

I use aluminum oxide in my cabinet.  lasts much longer than Coal slag.  I use the Tractor supply coal slag outdoors for big pieces...I prefer the finer stuff (red bag) I get clogging/blockages with the coarser black bag.

 

Like Richard I use a needle scaler first on many parts.  Noisy but effective. Wear breathing protection the old paints have lead

[ri702bill 8,564]

1 hour ago, rmaynard said:

I use a 60 gallon, two-stage compressor. The label says 11 CFM @ 90 PSI, but it's hard-pressed to even maintain about 7 CFM at 50 PSI. It runs constantly

We use a Sears 2HP 60 gallon oiless - noisy but mostly effective. Like @squonk, we tossed the China Freight siphon gun for a new TP Tools unit - overall better performance, but the compressor still struggles to keep up, not as bad as before. I stop when the compressor drops to come back on at 80 PSI and let it refill - usage is probably not more than a 25% duty cycle, at best.....

[Maxwell-8 4,359]

I tend to wire wheel most of the paint before sandblasting, prices of power have come up to 80 cents/Kwh, sandblasting isn't cheap where I live.

 

I have a ton of rims to sandblast, so that is going to keep me bussy for a while.

[pacer 3,174]

I "sand" blast a LOT and for cleaning up an old wheel horse Its hard to beat 'Black Diamond' in FINE grit (red lettering) in 50# bags for about $12 at TSC (its the coal slag mentioned). Larger grits will be prone to clog your gun. You can get into some pretty pricy media with glass beads, etc, so that $12 price for Black Diamond along with doing a good job of cleaning is hard to beat. I'll go thru 5-6 bags doing a horse.

 

I also must also stress that a pretty decent sized compressor is a must if you plan to do a lot of blasting -- The CFM (cubic feet minute) is the number to go by, Tank size is not critical as long as you can get a ..... minimum? of say 15-16 CFM which will almost certainly call for a 2 stage compressor.

 

I have an 80gal tank with a 5hp motor running a 2 stage putting out 18-19 CFM and if I'm doing a big piece it will run constantly but will still be putting out the CFM which means I can continue working - I blast at around 100-110PSI (pounds square inch)

[squonk 41,649]

2 hours ago, Maxwell-8 said:

I tend to wire wheel most of the paint before sandblasting, prices of power have come up to 80 cents/Kwh, sandblasting isn't cheap where I live.

 

I have a ton of rims to sandblast, so that is going to keep me bussy for a while.

How bad are they? You might be able to just let them soak in a vinegar or electrolysis bath.