Topic: To Prime, or Not to Prime - That is the Question

[Dr. Frankenstein]

I started work on my '72 CB500 Four today, stripping the frame down to the bare metal and I noticed that the factory did not use primer. The bare frame is in good shape, a few small/teeny surface  rust stains here and there, more so on the rear winker frame but nothing horrendous - and while I'm not going for a 'right-off-the-assembly-line' finish, I'm wondering what benefits or detractors there would be to using or NOT using a primer; and if so, what kind? I'm thinking a primer/sealer might be good, but etching primer would work too - something for the paint (Rustoleum semi-gloss black) to bite into.  Any ideas...? 

[Flyin900]

Depends on what kind of paint your using and spray application. I shoot with a proper paint gun and a single stage paint, where a primer is a must for bare metal. If your using a rattle can like the Rustoleum, then some of those paints don't require a primer, as they have something already in the paint mix.

Read the instructions on the can and if it is a non primer type there is your answer. If it says use a primer before the top coat then primer it requires. The rattle can primer/fillers are a good and economical choice when your using a spray can.

Make sure you use a wax/degreaser liquid to wipe down the frame completely before you shoot anything.

[jaytee-nz]

It really depends on the paint you are applying to the bare frame / primer. If it designed to be applied to bare metal, there is no need to prime it. Conversely, if the instructions state that primer (and specifically, what type of primer) is to be used, then follow that instruction.

[Dr. Frankenstein]

Hey, Flyin'! Yeah, I used to shoot with a HVLP gun, but since I'm usually just doing frames and I'm pretty good with a spray can, I usually go for that option. I plan on using High Performance Rustoleum Semi-Gloss - I did a test today with the appliance black that seems to be a popular choice and the hi-performance, and I like the sheen of it better, the appliance paint is too shiny for my taste. I'll have to check the directions, as jaytee referenced.  And I always wipe her down with acetone before I spray, and then let it sit for a good long while, which it will be since I have to take apart, vapor blast and rebuild the engine first before I put it all back together.

[Mark1976]

   Regardless of what type of final top coat you're shooting, it's always a good practice to put down a coat or two of primer on bare metal surfaces, its there to promote good adhesion for final/top coat, among other things. Even rattle can paint will benefit from doing it in that manner. But its your your bike, your choice...

[Don R]

 I like the VHT roll bar and chassis paint, it's a semi gloss black and doesn't require a primer, although I prefer to prime it first.

[Ozzybud]

I use this Dupli-Color 1635. It does not need a primer as it it labeled DTM.  Perfect shine and goes on nicely!

[Dr. Frankenstein]

Good choices; thanks guys!

[jonda500]

I believe the original paint had phosphorus in it to get it to etch into the metal. I want to do mine without primer to prevent future scratches/chips from being able to expose the light grey primer underneath (not a good look!). Anyone know of a matte black colored etch/primer?
John

[Mark1976]

   There are dark grey (essentially black) primers.

[Ozzybud]

I believe the original paint had phosphorus in it to get it to etch into the metal. I want to do mine without primer to prevent future scratches/chips from being able to expose the light grey primer underneath (not a good look!). Anyone know of a matte black colored etch/primer?
John

PPG DP90LF is an epoxy primer that is the Industry Standard for Bare metal application(90=Black)  it is made in different colors and is used for bare metal and a seal coat before basecoat.

[seanbarney41]

I have never primed a frame.  Primer just contributes to excessive material thickness which, of course, makes it that much easier to chip.  Rust-Oleum (both the high performance and appliance epoxy varieties) really seems to bond well to bare metal when everything has been sanded properly.  I start with 60 grit on any rust pitted areas and go 80, 100, 120,150 and then Red scotchbrite.  If any original paint is left just make sure the edges are feathered and that makes a good base too.

[Stev-o]

I use this Dupli-Color 1635. It does not need a primer as it it labeled DTM. 

You use the engine enamel on the frame?

[Ozzybud]

I use this Dupli-Color 1635. It does not need a primer as it it labeled DTM. 

You use the engine enamel on the frame?

Yes, it's tough as nails and doesn't chip.