Primer or no primer on chassis parts

[Tom Elliott]

What is the norm on painting chassis parts (axle's, steering components,etc.) Do you all prime or not. Thinking of using Eastwood original chassis satin black. They say you don't need primer on blasted bare metal. What do you all think? Thanks, Tom

[Pinstripe]

I would be hesitant...

[pgerhardt]

Even if you don't want to use primer surfacer to get a real smooth finish I would at least use some self etching primer on bare metal to assure a good bond.

[Purdy Swoft]

If the lable instructions says no primer if sand blasted, I wouldn't use any. On cleaned with a wire brush chassis parts, I use Rustoleum primer.

[Kurt in NJ]

Although it isn't model A part(it's for Mertcedes G wagon turbo diesel conversion), it is painted with epoxy primer over media blasted metal treated with "Picklex 20" ---not quite a full gloss, more of a semi gloss

I was reading in the Fastenal catalouge in the industrial paints there are "DTM" --direct to metal paints, and coal tar paints, but it was too much $$ to try for play

[Tinbasher]

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Primers your friend. It's there for Adhesion and Corrosion protection.

TB

[darrylkmc]

Tom Elliott,

Rustoleum manufactures many products, some of which are available at our locally owned hardware store. One of which is Rustoleum Direct To Metal (DTM).

If you choose to use such a product, which I would recommend, clean the metal thoroughly with something like the product thinner and blow down with Clean Dry air.

I use 235 Naptha and some Japan Drier to reduce it, I believe most of the Rustoleum DTM calls for Acetone for thinner.

Darryl in Fairbanks

[Purdy Swoft]

Rustoleum has a primer named clean metal primer, its white and can even be painted over with lacquer. Rustoleum also has a primer named rusty metal primer, it can be painted right over firm rust and is red oxide color. If a persons aim is a perfect show winner that they expect to last a life time they would avoid these primers and only use the most expensive products that money can buy .

[Logan]

If you're going to paint direct to metal, the metal needs to be sand blasted or completely clean. There's no point in spraying over old paint or rust. Por 15 is probably one the hardest most durable paints out there, and if you spray it on good clean metal it'll probably be the last time you have to spray it. For me, I like spraying primer on my chassis peices. I can sand it and reprime a few times to get the pits out of the metal. I like my frame rails, backing plates, and axle assembly's to be as slick as you can get them. I even used a little bit of filler on my speedster chassis since it shows. Either way if you do it right, you should have good results.

[Tom Wesenberg]

I use DP90 and top coat it with DCC 9000. It comes out nice on sandblasted chassis parts with no rust pits. It should last more than my lifetime.

[Doug in NJ]

Many (most) primers have fillers like talc. Using this sort of primer on a chassis part is a bad idea, because the primer will be softer and weaker than the topcoat, and just make it easier for the topcoat to chip.

More than once I have used a primer under a topcoat, and ended up bead-blasting all the paint off, and re-doing it with just the topcoat. But I have never had a situation where I didn't use a primer, and later regretted it.

Of course, 2-component professional body paints are a totally different story.

As for the Eastwood Chassis Black, I used a lot of it (the "Extreme" version) on most chassis parts, and I used its matching primer too. That primer does not seem to have any talc filler. The Extreme Chassis Black dries hard as rock. You can speed up the curing process by baking the parts at 180 degrees for an hour or so, after letting them air-dry until the solvents have evaporated.

Doug

Doug

[maako]

POR 15 works very good for bare metal and light rust.

[Kevin in NJ]

The key is to use the correct products and keep it thin to prevent chipping.

As always read the directions and follow them for each product.

Epoxy to properly prepared surfaces is a very tight bond. Modern 2 part (2k) paints applied during the recoat window of the epoxy should give maximum adhesion.

It is winter time, epoxy paint should be sprayed when the part and environment can be kept above 60 degrees or so (again read the directions) for the right amount of time (depends on the paint). If the epoxy reaction is stopped due to cold it does not restart, this is per my discussion with the owner of SPI paints.

Avoid etching primers. They are a common fail point as they are too easy to apply improperly. Putting epoxy over them can increase the chance of failure. This is per my discussion with the owner of SPI and my observations over the years. I have seen a number of cars where the paint peeled off leaving a nice coating of etching primer.

POR 15 works great till it fails. It specifically sticks to rust as the instructions are clear about this. The problem is rust is not well adhered to the metal. So when it fails it seems to come off in a perfect sheet of the part.

Anyway, some things to consider.

There are lots of ways to paint stuff. You just need to know how the stuff works well enough to apply it properly. Read the directions and remember they are not recommendations, they are how the manufacturer found the product works best.

[BRENT in 10-uh-C]

Many urethanes are DTM, -even if not labeled on the can. Personally I think most of this has to do with how accurate of an aesthetic restoration 'one is trying to achieve. It is very easy to "over-restore" when primers are added under the topcoat. Also know that most primer/surfaces are not designed to be "bonders" like paints of a few decades ago ...but are now intended to be levelers of the surface which is being painted. Remember the thinner the mil thickness of all the paint combined will result in a more durable chip-free surface.