Can walnut shells be run through a basic 10 gallon pressure fed blaster? I'm looking for the best media to strip paint, rust, etc. from the body panels of my car. I hear walnut shells can be used without warping the panels. Is this true?

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Scott Wolfgang

BCA #37508
AACA #662211J

1962 LeSabre
1969 Skylark
1989 LeSabre

[This message has been edited by onebada$$buick (edited 10-12-2001).]

I have never used walnut shells but I doubt they will touch rust. I have used plastic and it works great, but again, they won't touch rust.

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Life long Buick fan,
1965 Gran Sport Conv.
1965 Skylark H/T
1948 Chevy P.U. with 401 in it.

Thanks for the info. Can you use these different medias in a 10 gal. pressure blaster?

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Scott Wolfgang

BCA #37508
AACA #662211J

1962 LeSabre
1969 Skylark
1989 LeSabre

[This message has been edited by onebada$$buick (edited 10-12-2001).]

I have used walnut shells in a vibratory tumbler, my current opinion is they are excellent for polishing, and will not cut! If you wish to cut paint you should use a cutting sand. I don't believe that warping panels will be problem unless for some unknown reason you try to. Sand will probably be your most economical choice, but if you go to the Buicks.net "shop" you will find an article on bead blasting which uses a glass or plastic bead. They work excellent, but are expensive so you only want to use them in a blast cabinet where they will be recovered (at least for a while).

Don't even think of using sand on a body panel! It WILL warp the panel, unless you are VERY skilled. Believe me, I had a few doors RUINED just a few months ago. I really didn't car much about the doors, (they were for a display and would never be used on a car) so I thought that would be the best way to go. I brought them to a guy who I had blast many things for me over the years, including sheetmetal. I told him to just dust the outer panels, I was mostly concerned with the jambs. Well they were warped beyond belief.

The friction of the sand hitting the panel creates a ton of heat. It is like a rosebud tip on a torch. Sanding off the paint or chemically is much safer.

Please, lets go over any method you plan on using. I don't want to see you regret your choice.

Have you thought about having someone else plastic media blast it? In a twon near me they do it for only about $350.00 and I have used this service, it is amazing. YOu get clean bare metal, no "etch" like with sand, it looks just like NEW metal you would buy at a metal supply.

Let me start where I should have to begin with.....

1. What do you plan on blasting?

2. Why?



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Life long Buick fan,
1965 Gran Sport Conv.
1965 Skylark H/T
1948 Chevy P.U. with 401 in it.

I want to strip completely the old lacquer off the car. The guy I'm having do the finish paint work recommends it (I've seen some of his work and I have yet to see a paint job that doesn't look like a mirror) and I trust his opinion.

There is a place locally that does media blasting that I have yet to get an estimate through (I did get an estimate on having the undercarriage blasted and treated with POR-15, with the engine and tranny removed first, of course, and the estimate was $1500). I just ran into some unexpected free time and I was thinking about saving a few bucks and doing it myself. I know they use walnut shells on the body panels and that's why I was inquiring about those. I'm guessing the estimate will be about $1500-$1700 to strip and another $700-$800 for the POR-15 treatment.

As soon as it'e stripped it's off to the body shop a guy in my local AACA chapter for any body work and primer, and then off to be finished.

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Scott Wolfgang

BCA #37508
AACA #662211J

1962 LeSabre
1969 Skylark
1989 LeSabre

Martinsr,
OK, you had a bad experience, and as you are a pro, I am hesitant to question your opinion, but for my and others, here goes...

I have used sand for spot removal of deep rust pits, I think succesfully. I used an open blaster, cheapest junk you can buy. It worked great! I blasted until the black holes were gone, and for 5 years there was no trace of their return. I sold it at that point. I understand a pressure fed blaster to be far superior to what I used. I also understand that a commercial blaster with unlimited air supply can warp panels with a careless user who blasts hard in a spot. If a person was using a high performance blaster they should be cautious of building heat, but most hobbiest users are just using a small blaster with a 5 hp or less compressor. I would have thought that just fine. I would have also thought that the "etching" would be good for the primer sticking (I don't know how to spell adeation, along with a few other words).

Bob, I am not basing my opinion on "a bad experience", I am basing it on what I have learned about the subject in 25 years in the business.

I never said a single thing about "spot sand blasting" if it sounded like I said "don't ever use a sandblaster on a car" I am sorry, I in no means meant that. I was refering to Scotts question "I'm looking for the best media to strip paint, rust, etc. from the body panels of my car". And in answering that question I will stand by my statement "Don't even think of using sand on a body panel". Believe it or not the lower pressure sand blasters are more likely to warp a panel than a high pressure commercial unit. The fact being that you have to concentrate the nozzle on a very small area to strip the paint off, this creates heat.

Take your little sand blaster out tonight, and sand blast a piece of metal....in the dark. That's right, in the dark. You will see sparks as the sand hits the surface of the metal. These sparks are proof of the heat you are creating. Strip a small area and then immediately touch that metal that you just striped, you will find it is very worm or even HOT.

The safest way to strip the paint (for the car) would be chemical. Second would be an 8" orbital sander with 36 grit and then 80 grit then 120 to bare metal. I have striped many cars in full and part, and have learned that it is a VERY costly mistake to not give it the respect it deserves.

If you warp a hood, throw it away. If you warp a roof, throw it away. I visit another site where I have seen a few different people do just that, sand blast the roof of their car and have to cut the roof off and weld on another. I don't want to see any home hobbiest have to learn a lesson like that!! Striping paint is one of those things that I say, pay someone to plastic media blast it.

It is just the best spent money I can imagine considering the money that you would spend on chemical or sand paper and the ENORMOUS mess it creates.

If you do strip a car at home, my best advice is ONE PANEL AT A TIME. Strip it, and prime it. If it needs body repair, srtip it, do the body repair and prime. Go on to the next panel and so forth till you are done. Nothing has sent more classic cars to new owners or the wrecking yard more than striping a whole car and being overwelmed with the HUGE task of the project.

The advice I give is directed straight at the persons skills, tools and work space, that I have determined. I know I am going to be wrong once and a while on my determination of what they are capible of but in the long run I am pretty close.

I don't often even say what "I" would do, that may be very different. I say what I think would work best for the person asking.

This is a very big job that noone should jump into. This is why I asked "Please, lets go over any method you plan on using. I don't want to see you regret your choice."

A fine vintage car can be destroyed in one wrong move. I would hate to see that. http://www.buicks.net/forum/smile.gif



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Life long Buick fan,
1965 Gran Sport Conv.
1965 Skylark H/T
1948 Chevy P.U. with 401 in it.

Thanks for the help. Sounds like orbital sanding the panels and spot blasting the problem areas is the way to go. http://www.buicks.net/forum/cool.gif I bought a "practice car" to test my skill on before I ruin my good one. Not that I want ruin the practice one. http://www.buicks.net/forum/biggrin.gif

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Scott Wolfgang

BCA #37508
AACA #662211J

1962 LeSabre
1969 Skylark
1989 LeSabre

I have found that if you start with 36 or 40 grit, and just start to take it off. Then switch to 80 grit to finish it. The 36 or 40 WILL cut metal and it is a easy to cut up the edges of body lines and the like.

There is nothing more important than useing the best paper you can buy, and changing it often. HEAT is created with wore out paper!!

I thought you should see this. It is a question and some answers from a Camaro forum I visit. Just some more support for the dangers of sand or media striping. I do have to say, that I have never seen a plastic media srtip cause any problems.

question....I looked at a car today with some pretty nice features. However, when you looked down the sides of the car it looked like the skin might have been damaged by sand blasting or something. There were faint imperfections (low spots) in all the side panels. It didn't appear to be any kind of accident damage. The color was dark.
I mentioned it to the owner and he seemed to think that a good primer filler would solve the problem.

Will the primer solve the problem by itself? Won't it shrink like bondo over time?

1.Be careful on a deal like that. The shop that media blasted my Monte Carlo ruined the hood, it made a better washboard than hood after they were done with it. They did buy a replacement but not in any kind of a hurry.

2.If it has in fact been sandblasted, Ditto's to Tom's comment. Stay away from it.
A buddy of mine who works at a welding shop got the bright idea to have the shop sandblast his 56 Chevy. Wave City!!
The worst part is it changes as the sun, temp changes. Some days it looks OK other days Surf's UP


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Life long Buick fan,
1965 Gran Sport Conv.
1965 Skylark H/T
1948 Chevy P.U. with 401 in it.

Never use sand to remove paint from a vehicle. The sand will
heat the metal and distort it. Ever go by a bridge that they
were sandblasting? The blue flame you see jumping is caused
by the friction of the sand against metal!

I just had my skylark media blasted with plastic (looks like sand)
but breaks apart before it can heat the metal.

They now use a variety of media!

PLASTIC
WALLNUT SHELLS
BAKING SODA

Good Luck Carroll

Anyone know of who does soda blasting in eastern Massachusetts?

Never use sand to remove paint from a vehicle. The sand will
heat the metal and distort it. Ever go by a bridge that they
were sandblasting? The blue flame you see jumping is caused
by the friction of the sand against metal!

Good Luck Carroll

Not that it matters much but it is not heat that warps the panels. Believe it on not in tests I have done, the metal temp actually goes down from the air being blown on it!

The warping is caused by "mechanical compression" of the molecules. Each grain of sand acts like a little hammer striking the metal. It pushes the molecules in the top layer of metal around "enlarging" the surface. This process is used FOR you in shot peening rods. It forms a "pressure" on the surface of the rod making it stronger.

Brian

OK, so from this comment, could you suppose that it is the operator of the sand blast equipment that causes the damage with high pressures rather than the sand media itself? In otherwords sandblasting might be OK if it was used by an experienced operator?

I was told by a media supplier that what was becomeing a very popular media for stripping in the automotive blast industry was "Garnet". I saw some, and felt it was no more than a fine heavy sand. This was probably a benifit for recycling equipment, but no easier on the surface than the operator was able or willing to be.

This is just a topic which really interests me...