Sandblast Resist

[Larry Cazes]

Can anyone suggest a method for masking a section of a piece to protect it from a sandblast? I would also prefer it to be somewhat waterproof because I will be wet sanding and polishing as well and was hoping to find a product that would survive the process from start to finish.

[Sky Campbell]

I use rubber and vinyl resists from 3m for flat glass. For curved and organic shapes I use a combination of plastic tool dip and hot glue. I'm always looking for alternatives and what works.

[Pete VanderLaan]

I need to digress a bit.

The single most important thing in sandblasting is the way you do it. Gravity feed blasting which is the cheap and initially attractive way to do it is the single worst way to keep a resist on the work. It requires about 90 PSI to make a gravity syphon feed work. That in turn will rip the resist off any deep cut. What you need is a pressure pot system which delivers both grit and air through the hose. These systems are pinpoint accurate and can use nozzles as small as 5/32nds.

Beyond that, I used bill board tape. I bought a few thousand square feet of it 20 years ago and still have quite a lot. A -21 contact paper actually works very well but it needs to be A-21. I have never used tool dip. Buttercut might work better under water but it has no finesse to it. Also, buy a big big box of exacto knife blades. Change them a lot. When you hear that "tick" change the blade. I use to buy the things five thousand at a time.

[Brian Mazrim]

I've found tool dip to work well as a resist, but I think it just sticks to glass by suction or elasticity. It slides right off when it gets wet.

[Eben Horton]

I like electrical tape.

[Mike Marth]

As a Printer / sign Maker I've used the Vinyl for signs and banners
with very good results, blasting in a cabinet using silcon carbide.
the best part is you can get line art cut into mask patterns real easy.

[Larry Cazes]

I need to digress a bit.

The single most important thing in sandblasting is the way you do it. Gravity feed blasting which is the cheap and initially attractive way to do it is the single worst way to keep a resist on the work. It requires about 90 PSI to make a gravity syphon feed work. That in turn will rip the resist off any deep cut. What you need is a pressure pot system which delivers both grit and air through the hose. These systems are pinpoint accurate and can use nozzles as small as 5/32nds.



Pete, I am renting coldshop time at a public access shop so I'm not absolutely sure what kind of system this is. Last time I used it, though, the compressor was set at 45 PSI and it worked very well at that. I am looking into buying some basic equipment for myself, though, and Ill keep this in mind.

Lots of godd suggestions for resist here. Today I am working on another piece and I have both contact paper and electrical tape available and I will experiment with both. Thanks everyone :)

[Pete VanderLaan]

A pressure pot that is run at 45 PSI would really be very aggressive and more than you need. For fine resists, 25 PSI is plenty assuming the nozzle is small. It should be adjustable, even in a public shop. The nozzle type will be what they have- period. It will be worn out which will make it spray a wide pattern which is bad. I would think that electrical tape would turn really gummy.

[Larry Cazes]

Turns out the electrical tape worked very well and held up to the sandblast fine. I am in the process of finishing the polish on the piece so I just taped all but the surface to be polished and I dont have to worry about scratching on the untouched surfaces as well. Looks like the electrical tape is a great solution so far.

[Allan Gott]

The nozzle type will be what they have- period. It will be worn out which will make it spray a wide pattern which is bad.

I get around this by finding out what size nozzle fits the gun, buying some of my own and changing out the "public" one when I use the cabinet. Small price to pay for accuracy and control.

[Eben Horton]

Turns out the electrical tape worked very well and held up to the sandblast fine. I am in the process of finishing the polish on the piece so I just taped all but the surface to be polished and I dont have to worry about scratching on the untouched surfaces as well. Looks like the electrical tape is a great solution so far.
Did you doubt me? :):)

[Pete VanderLaan]

Did you doubt me? :):)
********

I have to. It's part of my contract to be a curmudgeon.

[David Patchen]

For light stuff (220 grit, <40psi) electrical tape is good. When I want to trace a specific cane stripe in the glass I use a clear vinyl tape since you can see thorough it and know when you are tracing the line well. Black tape is trickier to follow a specific piece of cane. Also for masking large sections, I use a thick vinyl tape that's 2" wide from TAP plastics. It's also super-sticky so would probably be good in water. I only do light blasting so all of these wouldn't likely stand up to anything stronger than the above.

[Rob White]

Speaking of sandblasters, does anyone know of a place in the San Francisco area that rents a pressure pot sandblaster with 80 to 120 grit? I want to be able to do some deep cutting sandblasting.

Rob White

[Larry Cazes]

You might try BAGI here in San Jose. I don't know all of the characteristics of the sandblaster they have but I used it a week ago or so and it worked well for what I was doing.

[Holly Wallace]

I think Jay Musler rents his sand blaster- he's in Oakland.

[Brian Blanthorn]

I need to digress a bit.

The single most important thing in sandblasting is the way you do it. Gravity feed blasting which is the cheap and initially attractive way to do it is the single worst way to keep a resist on the work. It requires about 90 PSI to make a gravity syphon feed work. That in turn will rip the resist off any deep cut. What you need is a pressure pot system which delivers both grit and air through the hose. These systems are pinpoint accurate and can use nozzles as small as 5/32nds.

Beyond that, I used bill board tape. I bought a few thousand square feet of it 20 years ago and still have quite a lot. A -21 contact paper actually works very well but it needs to be A-21. I have never used tool dip. Buttercut might work better under water but it has no finesse to it. Also, buy a big big box of exacto knife blades. Change them a lot. When you hear that "tick" change the blade. I use to buy the things five thousand at a time.

We used a suction feed on ours

The gun made a suction n then sucked the grit up

We could run this at very low pressure we blasted with 280 sci grit

But we did have a vortex type reclaim system, 4 those than wanna knowmore on this vortex I posted here or on warmglass about it but was a while ago

I had 2 give the sandblaster away 2 make room 4 Sally

Was a sad day n I still miss her, can U ever move on from ur first blaster ??

Brian