Thread: Stripping and painting chassis before welding

Having had both sand blasted chassis and caustic stripping of chassis, although expensive I've become an fan of the caustic stripping method as it gets to rust both inside and out as well as removing the paint.

Its a good idea to do one or the other before taking it off to the welder as it will identify areas that need repair.

If you do either make sure you do a phosphate wash or coating inside and out as soon as possible to inhibit rusting.

So once the chassis has been stripped, should I paint with penetroil and then coat with primer or just prime and use penetroil as a thinner when painting?

I thought most used the moisture cured urethanes these days on chassis (eg: kbs/por) You can just brush paint it that way

seeya,
Shane L.

I would not recommend covering your chassis with urethane, if thats the intention, and then sending to your welding mate. Heated urethane still has the potential to release cyanates according to the spec sheet I read.

I would recommend you chemically strip, then weld, sand blast and paint. Phosphating the inside of the chassis sounds like a good idea, interesting to hear how people have done it.

I'm using paint stripper, then garnet blasting, followed immediately by kbs urethane brushed on. The blasting provides a clean and keyed surface.

If you are only chemically or mechanically cleaning, and find you have small amount of oil staining and rust dimples then use manufacturers 3 stage process. Degrease and wash. Then phosphate and wash - you'll get a change in colour when dry but don't try and remove. Then urethane paint.

If sandblasted then no need for degreasing or phosphate, just the top coat - assuming you avoided handling the blasted area, and your blasting took out rust in the dimples.

Paint stripper hurts on bare skin so water handy and it eats nitrile gloves

Unless you have a filtered spray booth, you are completely covered head to toe and full face independent air supply do not spray paint with the urethane as it contains cyanate.

Someone recommended water base industrial coatings by Pheonix in Perth. Anyone been able to compare them to urethane?

Don't use chlorine based oil cleaners and the like as the arc turns the chlorine into phosgene. http://www.brewracingframes.com/safe...sgene-gas.html

the cheapest way to strip a chassis is to probably buy a box of those "strip it" discs for your 4" angle grinder ... and get too work. It'll be slow, horrible, messy, wont' get into the difficult to access places. But it will also be easy and effective.

You could do sections of the chassis at a time and brush coat soon after clean/stripped.

this sort of thing

4 X 125mm 5" Poly Strip Disc Wheel CAR Paint Rust Removal Clean Angle Grinder | eBay

seeya,
Shane L.

If you are going to the trouble i would get the chassis galvanised after welding.

For clarification, my intent is to strip the chassis (with those discs) then do a first coat to stop surface rust between striping and welding. Then finish painting after welding.

I'd think the easiest way to proceed would be to do whatever repairs are required... Then strip the chassic and coat it. Otherwise you'll be re-doing the repaired areas all over again after the repairs are done.

seeya,
Shane L.