Have you ever asked yourself what TYPE PRIMERS SHOULD I USE FOR MY PROJECT, WHATS THE DIFFERENCE BETWEEN SELF ETCH, EPOXY, URETHANE AND LACQUER AND WHAT DOES 1K AND 2K MEAN? If you have, here is a quick run-down on the primers. This is a question I get asked the most, and using the right primer is like choosing what type of foundation you are going to use building your house. So what I will do is go through all the different type primers and explain their features and benefits, and where you would use them. First off is the difference between 1k and 2k primers. The "k" in primer stands for component, but in Europe it is spelled with a "k" (ie Komponent) So a 1k primer means only one component so just the primer is needed to spray on a panel. 2k primer means 2 different components so the primer and a activator is needed before spraying on a panel. A reducer or thinner is not considered as a component, just the hardener. Lacquer primers and self etch primers are 1k primers. Epoxy and urethanes are 2k. Lacquer Primer - This is still widely used due to its seemed cost point, but if you consider how much dry film build a lacquer primer gives you, it is the most expensive primer to use, and the worst. It can reverse to a liquid, it can react when topcoated with another product, it does not provide rust resistance nor corrosion protection. Self Etch - Self etch has been used for years, and for a lot of paint companies they still make you use if a warranty will be covered by them. Self Etch is a acid that basically burns its way into the metal. Self Etch does not harden like a urethane or epoxy, once dry, it can reverse back into a liquid state. Self-etch is excellent for corrision protection and adhesion to most any type bare metal, but is not recommended to sand. Self-etch does not have much film build, so if you sanded your car with 180 grit sand paper and wanted the primer to fill in the scratches, this will not do the job. You can however put a coat or 2 on the panel, let it flash then topcoat it with a urethane primer. This primer is good for a restoration or a new aluminum panel. Urethane Primers - These primers are used in 90% of production body shops across the US. Urethane primers offer excellent build, quick drying, sands easy and are not reversable which means once it is hardened it can not go back into a liquid state. Urethane primers though, do not have good, if any, corrosion protection, they do not help in the prevention of rust and do not have good adhesion to bare metals. So if you are just repairing a couple of dents in your fender or door, this would be the primer for you. Epoxy Primers - Epoxy primers are the ultimate in adhesion and corrision protection. They also provide excellent film build. Epoxy is the best choice for a restoration because it helps resist moisture. Since most restorations take over a year to complete (except for on t.v.) Epoxy is a great choice once you have completely stripped the vehicle down to bare metal, You can do body work on top of epoxy, Body filler sticks well to sanded epoxy. You also can paint over epoxy (not recommended with self etch because the TiO2 (white pigment) will turn a browish tint when applied directly on top of self etch) On the downside, a lot of epoxy primers take a long time to fully cure, some shops claim epoxy does not sand well, thats usually due to the epoxy not being fully cured yet. However some epoxy primers now can be accelerated to dry very fast with the ability to sand very easily, making epoxy the all around best choice to use for most any project, especially restoration.