Epoxy primer
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[[Image:54_Dodge_Coronet_in_primer.jpg|right|thumb|350px|A 1954 Dodge Coronet body with a fresh coat of epoxy primer.]] | [[Image:54_Dodge_Coronet_in_primer.jpg|right|thumb|350px|A 1954 Dodge Coronet body with a fresh coat of epoxy primer.]] | ||
| − | Epoxy primer/sealer is a non-porous finish that is typically recommended as the first basecoat over bare steel. | + | Epoxy primer/sealer is a non-porous finish that is typically recommended as the first basecoat over bare steel. Epoxy primers are also used as tie coats to other materials such as composites, plastics etc. Each product is formulated differently so its important to check with the manufactuers's data sheet to check the exact surface preparation procedures for the various substrates. |
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| + | New formulations of epoxies are now being marketted by most manufacturers as surfacing primers. Those epoxy hybrids are direct to metal surfacers that act as both an epoxy and a 2k surfacing primer. The convenience of those formulations lie in the fact that you only need one product where two were previously needed. | ||
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| + | One word of caution with any epoxy formulation. Epoxy resins don't like acidic environments, some paint will not harden when an acid is used on the metal first. There is no need to treat metal with metal treatment prior to epoxy priming. Actually, some manufacturers specifically forbid the use of metal treatment before the application of the epoxy primer. Primer simply does not adhere to the metal when acid is present...One epoxy that is common in the hotrodding community is House of Kolor KP2-CF. That primer and any other epoxy formulation from Valspar must not be sprayed on metal that was treated with metal treatment (Ospho, Picklex etc...) or it will delaminate... | ||
Epoxy primer is a two-part mix, with a hardener that has to be added before spraying. | Epoxy primer is a two-part mix, with a hardener that has to be added before spraying. | ||
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==Body filler and epoxy primer== | ==Body filler and epoxy primer== | ||
| − | + | There is a debate amongst proffessional bodymen with regards to using body fillers over or under epoxy primers. Many advocate that it is best to use body filler directly onto metal as it provides better adhesion. Others refer to the corosion protection advantages of the epoxy before body filler method. However, no one is quite sure how to deal with the sand through around a body filler that is put onto epoxy. The epoxy layer is compromized around the island of body filler...what to do then before adding another coat of body filler? Trying to keep a layer of epoxy primer under a body filler repair is just not practical sometimes. Its much simpler to add body filler direct to metal and it works just fine. | |
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| + | One word of caution though with filling with body filler over a welded seam or any seam that could let any humidity through from the back side of the repair (all welds could be porous, have pinholes through to the other side of the weld although the are not readily visible). It is good practice to use a water proof body filler in those cases or use a good coat of epoxy on the weld seams to prevent any humidity from reaching the body filler from the back side. Regular body filler is not water resistant and the talk in them will swell if exposed to humidity. Waterproof fillers that can be used are milled glass and all metal types which will not swell as readily when exposed to humidity. | ||
| − | + | Note that commercial body shops don't generally use epoxy primer under body filler because it's not cost-effective. However, a very limited number of car manufacturers specifically require epoxy primer to be used under body filler for certain specific applications for guarantee conformance. | |
==Spray (rattle) can epoxy primer== | ==Spray (rattle) can epoxy primer== | ||
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