The Stovebolt Site Forums The Shop Area Paint and Body Shop Epoxy Primer then second primer?

I saw on the SPI site and article " The Perfect Paint Job " It list the order of painting like this

2 coats Epoxy Primer
2 coats 2K primer
2-3 coats base
2-3 coats Clear

SO I have bare metal and picked up this Transtar 2K epoxy primer. I want to put this on the bare metal and later put down the other primer before the basecoat.

Is this ok as long as I do not use single stage Urathane or acrylic enamel over it I am good right?

Thanks

IMO it all depends on the epoxy you are using. Some epoxies have a better direct to metal (dtm) adhesion than others. Some epoxies are not that user friendly in wet sanding (loading of paper results) or can not be used as a high build, others can. Some epoxies are not compatible with rust conversion coatings, some are.

In many cases, the epoxies that are not readily sandable will have to be topcoated with a high build primer to make an easier job of sanding. For example DPLF, once cured, does not present a good mechanical bond for additional coats of other finishes, and for best results will need to be scuffed, reshoot the epoxy, then shoot high build within the recoat window.

These are just a small list of things to consider to insure you have good compatibility from start to finish. Lastly, if SPI is giving recommendations, they likely are speaking for their own products. i.e.: given all the variances listed above, it would be best to consult the manufacturer of your paint for recommendations. I'm not familiar with the Transtar brand, but I normally recommend looking at all the intercompatibility issues between your PLANNED products before making any purchases. Then, if any inter-compatibility issues arise, you can alter your plans to accomodate.. with much less expense.

Understood. I once read buy a paint SYSTEM by chosing the color and then the manufacturer and stick with the whole system. Primer(s), Base and clearcoat.

I should stick with that advice and not get caught up in playing chemist.

If you have a question about compatibility call and ask Barry at SPI, he'll help you out and steer you in the best direction for your situation even if it means recommending someone else product to get you there.
Also he will tell you that once you put the transtar down if it's cured... your good to go finishing with the SPI (I bet)

From my personal experience, epoxy primers such as PPG DP90 are better suited as a sealer which you recoat after the recommended flash time with your top coat. The epoxy can be mixed as a primer or as a sealer.

I have always had better success spraying bare metal with an (acid)etching primer. These primers generally mix 1 to 1 and are very thin. You will spray 1 to 2 light coats that are nearly transparent. Once it flashes you can scuff the surface with a red scotch brite. At this point you can use body filler where necessary and then move on to your 2K urethane high build primers. Once you have sanded the 2K primers and your are ready to top coat you will need to seal the vehicle. You can now use the epoxy as a sealer or use the sealer recommended by your paint store. You can top coat epoxy with acrylic enamel, single stage or basecoat/ clearcoat. It is best to use one system from start to finish such as PPG, Sikkens, or Dupont.

Transtar is not a bad product. As MPandC mentioned above, when using epoxy as a primer you can experience adhesion problems and it does not sand well, it is like he said it gums up your sand paper. The etching primer has excellent adhesion to bare metal. If you look on the back of the Transtar can it should show an option to mix the epoxy as a primer or as a sealer. I would save it for use as a sealer. I hope this helps.

Interesting hearing about other epoxy primers sandability.
I find the one I use to sand great once cured and never have any loading up of the paper that won't blow off with compressed air or wash off in the bucket.