Sanding And Paint Prep

[DWaits]

After sanding what is the best way to prep the surface before priming?

Thanks!

David

[Barry]

I'd use something like Pre-Cleano to strip the surface of any grease or dirt. I'm no painter, but that is I have heard. Maybe someone else has more info.

[Lmackattack]

I wipe the bare metal surface with any type of paint thinner /cleaner. this will get the grease off the surface. also use a blow gun (with a filter) to get the sand grit out of the cracks.

thats my .02

[Rob]

This is along my level of knowlege, but I need more information as to how much bare metal is showing, what grit of sandscratch are you trying to work with, what your final topcoat will be, and what your budget will allow etc.

Rob

[DWaits]

This is along my level of knowlege, but I need more information as to how much bare metal is showing, what grit of sandscratch are you trying to work with, what your final topcoat will be, and what your budget will allow etc.

Rob

←

Rob,

I would say about 45% will be down to bare metal, the other 55% is either original paint or primerd from the previous owner.

It might be better for me to back up a little and tell you what I am working with.

around ten years or so the truck body was sand blasted by someone else who did not take the time to do it right, then they primed it and let it sit outside for a few years.

Parts of the body has rust coming back up thru the primer and parts of it held up OK.

I am trying to sand most of the truck that needs work and prime it again and use a clear coat to get rid of what rust I can.

I will not be painting for a while and the truck is inside so I am thinking the primer with a clear coat should hold up untill I can get all the mechanical work out of the way

and get it running the way I think it should run.

Then when all that is done I hope to start on a real paint job.

My goal now is to try and stop the rust that is there now and prevent more from coming up.

Thanks!

David

[Rob]

Hi David. Primers and other undercoats were never meant to be exposed to the elements for any period of time. Most are porous, (hence the rust coming back through) and UV radiation further breaks them down chemically. Prime coats, (both surfacers and sealers) are meant to be topcoated before exposure to any elements. With nearly 50% exposed bare steel, and the remaining original paint film thickness reduced by prior sanding, I would highly reccomend that you have the remaining paint removed as the surface integrity has been compromised. After thorough preparation, and cleaning, a phosphoric acid based "wash primer" could be applied to the bare substrate. This would be followed by a double coating of an epoxy primer/sealer. Epoxy primer/sealers are not waterproof either but if the vehicle stays inside as you work with it, many years will pass before you have problems again.

Clearcoats are made to bind themselves to a compatible basecoat color. Undercoats are not compatible with clearcoats as the chemical structure is different. I would not spend youR money for clear and activator until you are ready to apply final color.

We use a lot of epoxy in the shop as it has worked well many years for us.

Rob

[DWaits]

This would be followed by a double coating of an epoxy primer/sealer. Epoxy primer/sealers are not waterproof either but if the vehicle stays inside as you work with it, many years will pass before you have problems again.

Thanks for this info Rob,

I was wondering if I was doing it right and you answered that question to a T.

Is there a brand of epoxy primer/sealer that I should look for?

David

[Rob]

We use Akzo-Nobel products. U-Tec is the brand of epoxy primer/sealers we use as there are four different colors available. We also use a non induction time activator. This product costs about $80.00 for a gallon of epoxy, and $35.00 for a quart of activator. I don't readily recall the numbers for the products, but any good paint vendor will be able to help you no matter what the brand. I can't stress enough the benefit to using an acid etch before you apply any undercoating to bare steel. The adhesion enhancement is well worth the cost, even if you use a direct to metal primer.

Rob