Well I'm getting ready to wet sand blast (WSB) my project car and I wanted some input form those who have done it and or have some direct or indirect experience with it. I purchased a wet sand blasting kit from a company back east. I tried a sample piece and was thoroughly impressed. I was able to remove the paint down to bare metal on the underside floor in under 5 minutes. It was incredibly fast. The primer that I am using is an epoxy primer by SPI. I spoke with the manufacturer and they said to steer away from using a rust convertor as they can be very tricky to remove from seams. They also said to just blast it and spray it the next day. The flash rust will not be a problem. What has been your experience

I know that the guy at my shop wont sandblast at all because the media is too aggressive, & can warp the panels.

As for waiting to the next day to spray the primer - especially with wet sand/media - since I've had flash rust over night when I wire wheeled small areas & thoust it would be okay overnight (I'm also in relatively dry SoCal).

You might consider using soda or walnut shells or other less aggressive media for blasting.

Hopefully Rick/Alien or some of the other body shop members will chime in here on your question.

Good Luck!
Tom
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I'm WET blasting therefore there shouldn't be any warping? Right?

Don't do it! You'll have sand coming out of the cracks for years.

Don't ask me how i know, still makes me angry talking about it ...



5 years (FIVE!) after the sandblasting:

I'm old school BUT for a full strip "dustless blasting" is the new kid on the block

Its wicked fast, uses about 80% less media versus straight media blasting. The wet plasma helps everything along and flushes the debris away. Correct is does not generate heat, in fact it gets cooler a couple degrees below ambient which eliminates any fear of warping. I've seen glass beads used as media.

Water will get everywhere so making sure the H20 has a place to exit is a must.
Warm weather would be an advantage. The bare metal finish is interesting since the water buffers the media impact and you don't get a gigagazillion micro craters.

I saw this demo'd on truck body parts both on aluminum and steel. On aluminum I would use it in a heart beat. I would do it on steel but I would still machine sand AND use a lite chemical metal prep.

You can also learn from Andy the resident German that in some places duct tape may help sealing off areas you do not want media to get into. In the end you are going to have media in places including your ears that you thought it wouldn't get into.

I'd second & listen to what Jeff has said, and what Sir Andy has pointed out! Good luck with the project!

I would use a rust converter especially if the color of the metal is still dark, but with a sponge to keep it out of the seams. Avoid any runs or sags and watch for little parts of the sponge hanging on the rough metal when you start painting. I spent about 4 months on a 42 ford jeep and it had so much converter on it we reblasted it and then I rewiped it with a thin coat of converter and primered it before I started wiping filler on it. The driver side and floor was pretty far gone. Epoxy non sanding primer then seam sealer then when it is ready another coat of epoxy non sanding primer thinned with the same brand single stage reducer ie: dt reducer to keep the orange peel down. Then I apply the sanding primer. I try to spread filler on the non sanding primer pretty quick like it was a coat of paint otherwise the primer will need to be roughed up and then you gotta watch for scratching through the primer. I use a lot of epoxy non sanding primer to avoid all the extra sanding. You can put the mixed paint in the refrigerator and even the cup off the gun If you gotta stop for awhile. You will need to watch the gun head and blow wash thinner through it if it has to set very long. I would also try not to blow the blasting material into cavities. Hope it turns out like you want it to.

Once a contractor asked me how did I like the job he did on my driveway and I said nothing turns out like I imagined it but it was ok.

Mark Whitesel (Mikey914/914Rubber) did this to one of his cars.
You can read his thread and watch the video he linked in.

Mark's Stripper Thread

Jim

my car was media blasted (non WSB) for $1100 in my driveway. No panel warping that I'm aware of. It came out very clean, but there IS a lot of hidden media in the car like Andy described (not a big deal to me since it falls out as I rotate the rotisserie frequently).

As far as flash rust.....In my experience, I've left the bare chassis in my climate-controlled garage for two months with minimal rust since then.....except where my sweat gets on the bare metal. Ideally it would be nice to immediately primer the entire car, but I had too much grinding/welding left to do. I probably should have primered the areas that were finished (like the front trunk or hood)

I own the wet system. ( Dustless blasting ) I have used it on a couple different cars. The main problems are :

The sand PACKS into the corners and crevices. You will have to dig it out with a screwdrivers or something similar. In the time it takes to get the blasting done, rinse it off with the HOLDTITE and then clean out the crevices and rinse them, the flash rusting has already started.

High humidity makes the whole system uselss as fas as the rust prevention goes. Here in Va where we get jungle like humidity, I have the panels starting to flash rust almost immediately, despite putting 2-3x the recommended amount of HOLDTITE in the mix, and the rinse

Despite what Tom T says about sandblasting in general, this setup WILL NOT warp panels. I have tried. When I first unboxed it I held the nozzle 1" off the center of a 914 trunk lid for well over a minute and it did NOTHING to damage the metal

It's a great system for the outsides, but IMHO it plain sucks in enough ways that I almost regret buying it

This would be the case for any blasting though, right?
Blasting stuff clean in PA on a humid day you could see flash rust forming before I was even done clearing the pedal cluster (using aluminum oxide from a bucket blaster).

I know when I was painting my 914, I tired to do all the body work pre-paint during the winter to control flash rusting (and this was with mechanical and chemical stripping).

Humidity sucks ass.

Zach

Need a nitrogen atmosphere paint booth.

Not really. Nitrogen does not carry moisture. You need atmosphere to bind water or solvent molecules to carry them away.

The shop where I work bought one before I came on. Same experience as scotty b. I think it's sitting in a box, in a corner.

I agree humidity is a monster, come to Florida its so humid it rains every afternoon between 1:00 and 5:00!

Now the fun two months August & September putrid heat !

Vysoc

But nitrogen does not easily create rust, which would be nice. The time when the sand from wherever becomes most apparent is when the spray gun mixes it out of the crevices and straight into the paint. Not fun at all.

Thanks guys. After talking to paint manufacturer, I'm going for it. Will strip with water and sand, have rotisserie so will spin often to get sand out of hidden areas, will mask off tubes, etc. We will see how it turns out. I'll post video as well. By the way this will also be in my build thread "V8 914 speedster build"

good luck

Exactly- no oxygen, no rust.

My comment was a a little tongue in cheek, but it would be interesting to try it...

Actually this looks interesting and you can get cheap ones now. Not pro models, but it may be all you need for a few jobs. You could use it to augment regular blasting and stripping, get all the heavy rust off, then sand and dry blast off any flash.
The big thing would be prep, blocking all holes to keep the sand out.

Remember, like scotty b has said in past threads, your compressor won't work, you need to rent a big commercial unit.

Or gang several compressors on a single line...

yeah, that problem too. Despite the nice lady at Dustless blasting being told EXACTLY my compressors stats, she told me it was more than enough to run the system.

Well I was intrigued so I went and bought an el cheapo, so far I just shot a rusty rim face and I'm impressed. I have a 4hp 3000psi power washer, the WSB unit was something like $70.USD ($119CA at princess auto in Canada)

I haven't done enough to review it and I have no holdtight so we'll see how much it flash rusts over night.
So far I'd say it has it's place, but care will have to be taken to to avoid the pitfalls. It makes a mess, you still get hosed with sand, but don't have to worry about breathing it in. Looks like it will go through a shitload of sand, I'd say I went through 50lbs just to do a rim face, but it only took me 10 minutes.

So this was the result of my quick test shot. As I said I don't have any Holdtight 102 (I need to find a canadian distributor) it's fairly high humidity out and I didn't dry it proper. Not to mention it was after dark and I wasn't dressed proper.
So it's starting to flash, but even with the flash it took off the heavy rust PDQ. If I just went from here and hit it with the dry blaster it would clean up damn fast.
The last pic of the back of the rim shows how heavy the rust was on most of the face.

As said you would have to be super careful if doing the body, but it will definitely be a useful tool.

Why not just use a regular sand blaster on a steel wheel?

Mark just probably wanted to blast some rust and the rim was easiest thing to find and do to test his new toy.

Body shop I sent my car to had it Soda Blasted and
I didn't get to go see the car for over a week.
Took this picture while it was sitting there.

Click to view attachment

Bit of both, yes it was handy, but I'm going to use this sprint star rim as a spare on my bug.

As far as a regular sand blaster or my blast cabinet using my 5hp (real 5hp) 120gal compressor I'd say this would have taken me about an hour+ to get this far.
For big jobs I've used a service in the past, but they have a minimum charge , make an appointment, get my ducks in a row, wait till they get here or take it to them...paint like crazy for the next 24 hours.
This was one hell of a lot faster.

Mark do you use air ratchets at work? Do you torque with them as well?
Some tools are great at what they do, but you have to reach for another tool to finish the job.
To me this did a great, fast job on the heavy rust, a bit of flash will come off PDQ in my blast cabinet. Better drying and holdtight and I should have minimal flash.
On flash and small parts I wonder if drying in my shop oven would help.

Not for everyone, it makes a hell of a mess.

Well I got busy wet blasting the 914. Ran out of sand (2000lbs). 90% complete. The blaster worked flawlessly not a single clog after blasting through 2000lbs of sand. Did not use hold tight. Spoke with my paint manufacturer and they said flash rust is not a problem for epoxy primer. Just hit it with scotch brite and a cleaner that they provide. Steered away from rust convertors or soda or anything that I would have to neutralize either acid or base.

https://www.youtube.com/watch?v=RZ0oQxO59Y8

IIRC you can reuse the blast media with wet blasting a few times (2 or 3).
If you supplier says otherwise, obviously go with that.

Zach

Yeah you can reuse the blast media....but then you would have to recover and dry before use. Then you would have to hope for some really hot days and spreading out the sand then collecting it again.........too much work when sand is so cheap and I really don't want to store 1000 lbs of sand. By the way, I am blasting where I'm going to cast a concrete pad......so the sand is going to some good use.

Mark- I have used this Krud Kutter stuff after conventional sandblasting to prevent flash rust. Works well, comes in a concentrate also.



Most big home improvement centers carry it.

Mark- I have used this Krud Kutter stuff after conventional sandblasting to prevent flash rust. Works well, comes in a concentrate also.



Most big home improvement centers carry it.

Allis Chalmers engine one week after blasting

Click to view attachment

Primed and painted PPG

Click to view attachment

If you do a search on flash rust you're going to get answers both ways.....1) use a metal prep (rust converter,etcher) 2) don't use a metal prep, etcher.

According to the manufacturer of my epoxy primer (SPI) they said Do Not Use a Rust Converter, flash rust is fine!

I guess the best thing is to call your paint manufacturer and see what they say. As far as I understand PPG also does not want you to use a rust converter. I believe that their reasoning is that people will not do a good job of neutralizing with water before primering it. Or that some of the acid gets stuck in the seams and does not come out. Eventually it does come out and it will ruin your paint job.