Sandblasting bonnet

[Yeldaw]

Hi, Both wings on my bonnet are starting to bubble with rust together with some rust on the inner wings and scuttle. The body shop has suggested sandblasting and respraying the whole bonnet but I have read some posts suggesting that sandblasting can distort the bonnet. Looking back at old bills from the previous owner it looks like the bonnet was previously sandblasted and resprayed about 10 years ago. What issues should I be aware of concerning the sandblasting process, is there a better alternative and what is the best way to stop any distortion. Thanks Dave

[MarekH]

Dear Dave,

If you send me your email address via private message, I can send you the instructions for my covered headlight kit which covers this topic in some detail.

kind regards
Marek

[Ole-xke1974]

You are correct, sandblasting creates a lot of heat and can distort larger items such as bonnets, wings, door skins and so on.
Dipping, stripping or soda blasting are the most common methods.
I took my bonnet completely apart and had it soda blasted before addressing the rust.

[Yeldaw]

Thanks, I was hoping not to have to strip down the whole bonnet. Marek I have sent you a pm.

[politeperson]

The whole process of commercial car body paint removal is one best avoided if possible.

Use poly discs on an angle grinder. Be kind to your car.

https://www.ebay.co.uk/itm/5Pcs-4-Poly- ... OSwUvldEnZ~

I have seen expensive disasters with shot blasting, media blasting, stripping and dipping.

Moving bare shells is dangerous.

Leaving cars at commercial premises in a queue to be processed is dangerous. "see you in 6 weeks".

Picking bare shells up with a lift truck is often dangerous.

Its all expensive too!

You must wear a full face helmet and welding gloves when using stripping discs. Do it at home outside in your own time.

Stripping discs are very effective, cheap, no metal sparks, doesn't heat or scratch the metal. Very fast too, do it at home.

Not good on underseal, this really needs heat and a scraper.

I have stripped the paint down to bare metal on whole cars for a few pounds.

Even my local shot blasting company recommends them.

Dont worry about rust inside areas you cannot get to. You will wax inject the box sections and the back of the welded areas after the painting and assembly.

If rust hasn't come through 1.2mm sheet steel in 50 years, it isnt going to.

Watch edges though.

Here is one i did earlier.

[Craig Balzer]

An option is vapor blasting (AKA water blasting, and a couple of other names). This system is the same as regular blasting but carries the media in water rather than air.

The benefit of vapor blasting is that the surface temperature of the target is only reportedly raised 10°F higher than ambient temperature.

I am not certain of which media is best for your application.

Craig

[rswaffie]

I can also vouch for the DIY approach. I purchased a heat gun from Screwfix @ £12.99, 20 strip discs and a set of paint scrapers. Did the whole car, including the underside back to bare metal.
Too many horror stories about the baking/dipping process, particularly regarding the chemicals not being fully removed/neutralised and eating the new paintwork from the inside 6 months later!
In the hands of an experienced operator, media blasting can be done safely but there is still a small risk.
A heat gun carries a small risk of distortion but you would have to try really hard to do so!

[jmckengineer]

I did some work on a e-type roadster a few years ago on a boot lid using soda. I used an Apollo blasting system, at only 30psi which just took the layers of paint off...but yet retained some old filler for manual removal, it removed the paint so carefully that you could still see the original factory metal forming and sanding marks on the surface of the pressing, the system works with all types of blasting abrasive from walnut shells, to soda and other abrasives like garnet or crushed glass. you can find more info at: www.apolloblasting.com

Elon Musk drives a Tesla, & as a keen restoration enthusiast & founder of Apollo, I use non other than an Apollo abrasive blasting system for all my own classic car & aviation restoration projects, only the best will do!

Any questions feel free to ask me directly!

[Ash]

The last car I stripped completely was with paint stripper bought from my local motor factors. I then used a rotary wire brush to remove any residue and washed off with thinners. Time consuming but kind to the metal

[abowie]

I used an Apollo blasting system,

"Apollo Blasting was founded by Mechanical Engineer Jason McKenna"

[MarekH]

Doh!

[Fspp369]

IF you are going to sand blast a body make sure the blaster allows time, you cab remove all of the rubbish but it must be done at a lower pressure and with a particular wide technique, standing much further away than usual, to avoid heat build up and pressure stress. it is not the normal technique!!!
Soda blasting does not generate any heat of note, and is very good at paint removal, and will cope with small areas of undercoat, BUT YOU MUST REMOVE EVERY LAST SCRAP OF SODA FROM ALL OF THE LITTLE CORNERS otherwise it will rot quicker than a cabbage!!
Also Sodablasting even with "doped media” [media with a fine aluminium oxide powder] will not remove any rust other than a light surface dust..so beware.

Iused to own a soda blast company and have done many car bodies, Sodablasting with plain media will take the paint of fully glassed “Critall” windows for instance and leave the glass unmarked
See Phantom3 rear window still fitted whilst aluminium body is blasted!!

Horses for Courses...

[jmckengineer]

I used an Apollo blasting system,

"Apollo Blasting was founded by Mechanical Engineer Jason McKenna"

Indeed, it was Andrew.

[jmckengineer]

Soda Blasting is good, but it takes greater air volume and pressure, in comparision with more aggresive medias to strip paint in comparison with garnet or crushed glass..I recommend using ultra fine crushed glass for jobs like these, at very low pressure with an aftercooler, blasting at 30psi ideally or less, to avoid warping panels and leave a nice surface finish for priming surfaces post blasting. Vapour/wet blasting can lessen surface damage from blasting and i recommend Corr-Ze™ rust inhibitor, which can be used with all blasting systems.

Any advise needed just ask! I've got a lot of experience...