Instructables

How to Mask Off an Area for Aggressive Sandblasting

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Picture of How to Mask Off an Area for Aggressive Sandblasting
In this Instructable, I will show you how to mask off a particular area prior to sandblasting to protect it, in this case I will be masking off the emblem on a bike frame.  This type of masking is ideal for aggressive sandblasting at a close range for long periods of time. 
 
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Step 1: Cover Area with Vinyl

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Cover the area you would like to protect from sandblasting with vinyl (with adhesive on one side).  Use enough vinyl that it covers more than the area you wish to mask.  

Step 2: Shape Mask

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Using a sharp blade, cut away the excess vinyl around the shape you are masking off.

Step 3: Cover Area with Electrical Tape

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Mask the area again over the vinyl with electrical tape.  Electrical tape will absorb a lot of energy which will prevent the tape itself from being sandblasted away.  Without the vinyl underlayer, the adhesive on the electrical tape will embed itself into your metal which can be removed by hand sanding.  I use the vinyl underneath because the adhesive on the vinyl does not get embedded as easily.  

Step 4: Shape Mask Again

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Cut away the excess electrical tape like you did with the vinyl previously.

Step 5: Sandblast Area

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With these two layers of masking material, your project is ready to be sandblasted.  Remove both layers after you are finished completely with your sandblasting.
hohum2 months ago

Thank you to all, for all of your input, tips, suggestions, I sincerely appreciate your helpful comments.

Jack G

When retexturing areas of injection mold after repairs, welding etc. I have used hotmelt glue with great success,good to cover edges of detail that must remain crisp and heavy enough to deflect aggressive grits and wears well, but above caveats about gun position apply and are critical to success. Build it up layer by layer as heavy as you need close to edges , then trim as needed to sharpen edges. just another way when other methodsnot as available or feasible.

It's a small internet! I work in blow molding. However, we just use duct tape to mask the molds and use a razor blade to trim to the pinch offs.

blanchae1 year ago
I've thought of using the same masking material that they use when they sandblast gravestones for "etching" in the names.
blanchae
What masking material would that be? and were can I find it? Please.
It is called sandmask - http://www.hartcoservice.com/sandmask
Thank you I'll try it out on my next project
shakeval1 year ago
where is the result, we'd all like to see it......you know, proof it worked and such
M40 shakeval1 year ago
The final picture shows the result... a well blasted surface and the masking material is still intact. Whether he shows the project itself painted/finished is a moot point as this is not about painting, bicycles, etc

The Instructable is indeed helpful to those of us who sandblast. I didn't know that vinyl/electrical tape was capable of absorbing/deflecting the blast media. I'll definitely be using that combo in the future.

Question: Would a couple layers of electrical tape work (without the vinyl layer)? Likewise, would a few layers of vinyl work?
zfoust M401 year ago
I sandblast a lot for the natural gas industry and we use some pretty serious coal slag abrasive. When it comes to having to mask off fine threads, there's nothing better than electrical tape. The abrasive WILL push the glue into crevices and crannies, but this is easily removed with some solvent (brake cleaner works for EVERYTHING).
I.P.Freely M401 year ago
I think I will try liquid electrical tape. Might work, might not.
Won't work, that stuff has ZERO durability for any purpose but wiring insulation, and that's only because nothing is really exerting force on it.
violet.sun (author)  M401 year ago
I first tried several layers of vinyl but the edges peeled up and I also blasted through all the layers. Next I tried several layers of electrical tape which held up great but the adhesive embedded itself into the metal which was difficult to remove. The combo of vinyl under electrical tape has worked the best for me so far.
Listen up - cause I am a genius.

1. Up to a point "rubber" types of media absorbs and deflects most of the abrasives energy - it flexes rather than cuts - but it will wear through eventually.

2. The direction of the gun has to be aiming the spray in a way that  is either near parrallel to the edge of the masking media or from the center of the masking media, to the metal around it.

- The maskign lifting is much like laying a sheet of paper on a flat surface and blowing at it - the paper will lift.

But if you blow at the paper, from the center to the edge, it stays stuck to the surface.

As much as the tapes have adhesive, and the bond may be quite good, with enough air pressure and hits by the abrasive, done close enough, for long enough, the abrasive blasting can lift the masking.

The same masking process is used in the sand blasting of windows - and if you do enough of the same pieces, you could make up a "permanent mask" out of silicon adhesive or rubber sheet - with it laid, clipped, / clamped / temporarily bonded into position.

The other thing is that you can paint on masking, using either latex rubber or slightly thinned neutral cure silicon - with turpentine, or even the contact adhesive.

As long as it's sticky and rubbery and is easy enough to get off either before or after painting without the rubber dissolving into the solvent.

Though that tends to be more of a time and paint depth issue.

Though with powder coating - it might just come away after baking.

Worth experimenting with I think.





The final pic does not show that it worked properly... we cannot see that the edges of the emblem were UN-touched... That is a lot of pressure blowing on those surfaces... I can see the edges peeling very easily while sandblasting... Just drill the rivets and pop the emblem off!
I restore old Raleigh ten-speed Bicycles and have done 3x so far.

You can tap out the head badge rivet and buy new hollow pop rivets (3/32" stainless) at a few places on the internet.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120986658043

This Raleigh Sports has a 1977 or later head badge (as evidenced by the solid rivet, and I don't know a source for these), the 1976 and earler bikes had hollow rivets (like 3/32 above) that allow you to see into the head tube of the bike.

This badge has already lost all its paint. A good friend of mine who restores Cinellis recommends that you cut down a fine paint brush until there are just a few hairs available, and then repaint the badge under a microscope to get it looking like new again.

Good luck !!
Painstaking work, to be sure. But why not just drill out the head badge and reattach when you're done? Better yet, get a new (vintage) one off eBay? http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=raleigh+head+badge&_sacat=0&_from=R40
Off topic, but it looks like this frame may have sustained a front impact at some point. Maybe it's the perspective of the photo, but that downtube looks bent. But hell, these old Raleighs are bombproof. She'll hold together:)
WPee1 year ago
Sign Shops can order a thin rubber mask with an adhesive and a peal away backing that they can CUT the mask for you.

NOTE: It is used for precision masks in stainglass, & glue chip, & gold leaf, glass works...etc.

I did a quick digital snap shot and emailed it to the sign shop and they sent back a very good rubber mask. (we both fugged the images a bit to MAKE-IT-FIT.)
The imaged mask was to be wrapped around a tube much like this bike example.

Saved a lot of screwing around looking for the sandblast mat materials.
Jburchim1 year ago
For those interested in using resist for sandblasting, it is possible to use contact shelf liner for gravity feed blasting, there are also different media for blasting, ranging from walnut shells, corn cob media, to Silica Carbide. Walnut shells are an interesting biodegradable option as a blast media, that is not overly aggresive.
Your instructable was well done and informative.
drmax1 year ago
Hi, I miss the picture with the result, too. Also can someone explain me, why this article is featured? What are the requirements, that an article gets featured? Seriously.
cjohnson431 year ago
Gaffers Tape, similar to hockey tape, is what we use at work when we blast jet engine parts.
Sounds4cc1 year ago
I find just about any tape works; Even blue painters tape, packing tape. etc. Dont care for duct tape, the heat from the beads/sand impacting the tape makes it real gooey.
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TinCan1 year ago
I've used multiple layers of self adhesive shelf paper, 3 layers seemed to work fine. It comes on a roll so you can cover large or small projects easily.
Nice instructable.. Normally I would just drill out those rivets and pop the emblem off and replace it after it is finished...
EET19821 year ago
Very cool. I never thought that was how you did it. Great instructable :).
Oh wow, that's how you do that. I am going to be repainting my vintage Peugeot soon, and I was curious how that was all going to work out. Thank's for the share.