Dave Jameson
New User
Epoxy primer is one of the best primers on the market, although the Nason brand is of older technology. It works ok, but, in my experience, does not lay out quite as smooth or is as versatile as, say, PPG, for instance. The PPG system is designed to be applied over properly prepared bare steel, THEN the necessary body-work can be performed.ie: The plastic filler can be applied directly to the dry PPG epoxy primer and will actually adhere better than to bare steel alone. This also protects the body filler from moisture. The problem I see with the procedure you are using, is the use of lacquer primer-surfacer. Lacquer is a very poor product with questionable durability. When lacquer is used over an epoxy, there is a risk of lifting, especially if the epoxy film has been broken or scratched, such as when sanding body filler. The ideal procedure would be:
1. media blasting or stripping the old finish either by mechanical or chemical means.
2. chemically treating & conversion coating the bare steel(especially important with aluminum or stainless).
3.prime with a quality epoxy primer.
4. perform necessary repairs,ie. body filler.
5. re-coat with epoxy primer to cover any bare metal areas.( The PPG DP-LF series epoxy primers when mixed with DP 401 will have a pot life of 72 hours @ 70 degrees F).The Nason system is 8 hrs. if I remember correctly.
6. follow with a QUALITY urethane primer-surfacer such as PPG K-36. This primer has excellent filling properties & will fill as much with 2 coats as 5 to 6 coats of lacquer. A much better AND economical product. The initial cost is a little more, but it actually goes further. Less VOCs too to keep the Feds happy. I feel it is very important to stay with a particular brand & system within that brand.
7. perform the necessary sanding. If there are any sand-throughs, you can put an additional coat of DP over the entire area as a sealer to obtain a uniform finish ready for top-coating. With low-hiding colors, this is a very important step to keep from using an excessive amount of color to hide the substrate.
8. top-coat with your choice of material. The choices are nearly endless, but if you stick with a quality urethane product, the results will have you patting yourself on the back.
The preceeding steps have ensured that you have an extremely durable undercoat that is chemically & physically stronger than most any topcoat that can be applied. Just as in building a house, if you have a strong foundation, the rest of the job will reflect that & last a heck-of-a-lot longer.
1. media blasting or stripping the old finish either by mechanical or chemical means.
2. chemically treating & conversion coating the bare steel(especially important with aluminum or stainless).
3.prime with a quality epoxy primer.
4. perform necessary repairs,ie. body filler.
5. re-coat with epoxy primer to cover any bare metal areas.( The PPG DP-LF series epoxy primers when mixed with DP 401 will have a pot life of 72 hours @ 70 degrees F).The Nason system is 8 hrs. if I remember correctly.
6. follow with a QUALITY urethane primer-surfacer such as PPG K-36. This primer has excellent filling properties & will fill as much with 2 coats as 5 to 6 coats of lacquer. A much better AND economical product. The initial cost is a little more, but it actually goes further. Less VOCs too to keep the Feds happy. I feel it is very important to stay with a particular brand & system within that brand.
7. perform the necessary sanding. If there are any sand-throughs, you can put an additional coat of DP over the entire area as a sealer to obtain a uniform finish ready for top-coating. With low-hiding colors, this is a very important step to keep from using an excessive amount of color to hide the substrate.
8. top-coat with your choice of material. The choices are nearly endless, but if you stick with a quality urethane product, the results will have you patting yourself on the back.
The preceeding steps have ensured that you have an extremely durable undercoat that is chemically & physically stronger than most any topcoat that can be applied. Just as in building a house, if you have a strong foundation, the rest of the job will reflect that & last a heck-of-a-lot longer.
