Plastic beads for clearcoat removal?

[john hd]

was wondering if anyone has heard of or tried the use of plastic blast media in the removal of clear/plasticote?

a number of years ago i had some motorcycle parts prepped for paint this way. they were thin and fragile. i did not want them sandblasted.

i remember discussing the technique with the owner of the shop, when questioning him about it he gave me the following information.

it removes paint and nothing else.

it will not remove rust on steel.

no need to remove rubber or glass from a vehicle as the beads are not abrasive.

i leaves a film on the surface that must be removed with prep solvent before painting or primer is applied. unprotected steel can wait up to six months before paint.

what does everyone think?

with all the polishing going on lately, i'm wondering if farming out the clearcoat removal process would speed things up. and eliminate the toxic steps of polishing an airstream.

btw, the guy was working on a very expensive packard when i visted him. the bright work and glass was not masked off. the car was almost completely stripped. there was no damage at all.

comments or experiance with this method?

john

[Pick]

Sounds like the "cats meow", John. Of, course everyone will want to know cost. Are these only used in "glove boxes", or are they cheap enough that they can be used one time and disposed of?

On a side note, I have started stripping my propane tanks, that were painted more than once. I will have to do multiple applications of Citristrip to get them clean. I did polish a small area with SS and it did a super job.

[john hd]

pick

nope no glove box used.

the guy had an entire garage bay dedicated to the process.

he was reusing the beads.

post some pics of your tanks when you get further along with them!

john

[59toaster]

Yeah I have heard of it. They have come up with all sorts of new media blasting materials. They also use some crushed walnut shells with simlar results. The media is just hard enough to take the paint off but since it is not super hard like sand it cannot damage glass, rubber or even chrome.

[CanoeStream]

I have first-hand experience with using walnut shell granules in a compressed air stream (a large box, reaching in through rubber gloves arrangement). They are relatively inexpensive -- a venturi arrangement picks up the particles.

I don't know the numbers but suspect you'd want significantly different hardnesses to escape without damage. In the case of walnut shells, hardness is not much different than plastic but is certainly enough to abrade other moderately soft materials. It will remove plaster from acrylic, but you can burn the underlying material if you dwell too long on one spot. On the Packard I would agree, steel and glass would not be affected.

I refurbished some old light fixtures from the 1930's in building our home 15 years ago. The aluminum expansion housing in the picture below was as shiny as any vintage Airstream. It was corroded and paint spattered. No experience with the 'Shell Blaster' could prevent pitting and development of the matte finish -- even on the briefest exposure possible.

Classic Answer: Whether you can try the system beforehand, be sure to use it in a sample or invisible area.

[CanoeStream]

"Relatively inexpensive" -- the dust-free approx 1mm walnut granules are available in 50# sacks for less than a dinner at Chez Paul. That still doesn't make them any better for aluminum.

You wouldn't want to use this in your driveway or compost the waste -- walnut byproducts poison soil against many yard and garden species, tomato and apple included.

[greg176]

I have used plastic bead blasting quite a lot, we use it to strip paint from aircraft wheels for overhaul. It is a great paint remover (the best). and i use the machines to clean old outboard parts.However I would not try this process to strip an Airstream as the pressure and heat generated by the process would cause the skin to warp. This process would work on the heavy steel of an antique car but I remember a friend in trade school who tried on a 76 Plymouth- result one car that looked like it had been rolled. Stick to the chemical stripper.

[ALANSD]

This is an old thread I am reviving...can anyone share some more recent experiences on media blasting? I am thinking of using a "Speed Blaster" and either plastic or walnut ( which grade I do not know) to strip the nasty thick blue paint off my Excella's stripe area.
Is the Speed blaster from Eastwood a good item to use?

[ALANSD]

well no answers, so I went ahead after some research,, and got the blaster gun, 25 lbs of walnut shells, and will give this a shot. Literally

[bkahler]

The only thing I'd be concerned about is the amount of air pressure used during the blasting process. I know its REAL easy to stretch sheet metal when sand blasting (I have fenders from a Triumph TR3 that are stretched real bad, and no I didn't do it!). I realize you're using walnut shells but I think its the pressure and heat generated during the blasting process more than the media itself.

I'd start with as low a pressure as possible and work gradually up from that point.

Good luck and let us know how it comes out!

Brad

[CanoeStream]

I've used walnut shells on a test strip of .032" 5052 aluminum. Walnut shells did two things -- left a noticeably roughened matte surface (see here) and caused the sample to warp (concave on the side blasted). This problem has been noted by others. Test on an inconspicuous area first.

Also don't use walnut products around horses or where they might get in contact with a tomato garden.

Pictures! We want pictures!!

[Fyrzowt]

A friend of mine is in the log home restoration business. They use rice hulls to strip off old finishes on the logs, prior to re-finishing them. This might be worth a look for your application.
Dave

[ALANSD]

Thanks for the comments. I spoke with some car refinishers here, and a pro who does this for a living ( my job is too small) and walnut at 90psi or below was recommended. Also keeping the gun at an angle of 45-60 degrees is helpful. I am anxious to try this on my trailer as stripping has been very time consuming and not working well in this instance. I will photo and post a link once I get some done.

[Journalist]

the aluminum skin of an airstream is too soft for any sort of media blasting. You will end up with a dull gray finish that's nearly impossible to polish out.

[Fyrzowt]

Originally Posted by Journalist

the aluminum skin of an airstream is too soft for any sort of media blasting. You will end up with a dull gray finish that's nearly impossible to polish out.

I would certainly find or buy a piece of aluminum with the same softness as the A/S, and give it a trial run before trying it out on my trailer...

[ALANSD]

I will keep you posted. The opinions run the gamut on this.

[InsideOut]

I've seen a vintage trailer that was blasted with walnut shells...it looked very nice! It had a bit of a matte texture, but it wasn't at all objectionable. I actually thought it was a nice alternative to polishing or re-clearcoating.

Shari

[ALANSD]

I have heard good things about this method, and since I am doing the stripe area only and the small mid molding it seems like a good idea.
Tried it today, no media came out of the gun, just air. Not sure why, I will talk to the tech guy tomorrow. Disappointed but going slow on this.

[InsideOut]

Originally Posted by ALANSD

Tried it today, no media came out of the gun, just air. Not sure why, I will talk to the tech guy tomorrow.

Hopefully it's something simple like a valve or switch that needs to be flipped.

Could it be that the nozzle orifice was smaller than the media?

Shari

[ALANSD]

My thought, although I looked in there, and checked for blockage and it seems to be the right size. I did manage to shoot one or two pieces into my hand though. Felt just great
Being new to this process, I am hopeful its something simple that this dunderhead can't see!
I am talking tio the tech guy this morning. Of course it will rain tomorrow so I am off trying again until maybe Sunday.