John, The terms "sandable filler primer", "primer surfacer" and "surfacer" all refer to a heavily bodied product that is applied in multiple coats and then sanded down significantly. Their purpose is to provide a filling function for minor imperfections such as sandscratches coarser than about 400 grit. The term primer used together with the terms filler or surfacer implies a product that serves a dual purpose of primer for bare metal and filling minor imperfections at the same time. By contrast, the epoxy primer is considered a non-sanding primer for bare metal and does not perform as significant a filling function as a filler or a surfacer. It can be sanded but not as easily as a surfacer. Surfacers and primer surfacers sand very easily. In fact they are intended to be sanded, usually with something like 220 initially and 400 or finer finally. I prefer to use the single term surfacer for such a product as I like to shy away from products that are marketed to perform more than one function. In short, I believe a primer surfacer does not provide as good a product for priming bare metal as a dedicated product like epoxy does. Don't plan on using a Preval sprayer for applying a surfacer. That sprayer is not intended for that and I think the material is too thick for it. A spot (touch-up) gun will apply it, although not as well as a gun with a larger tip intended for the heavier material. In any event, you are not looking for a great smooth surface at this point since you will be sanding 80-90% of the surfacer off anyway. I have applied surfacer with my spot gun (1.0mm tip) and didn't worry about it. I wouldn't do that on something as broad as a typical automobile hood, but I have done so on my AC-B tractor hood since it is much smaller. Also don't bother with a surfacer on the cast - it's not generally worth the bother and the sanding effort that would be required. Save the surfacer operation for the sheet metal that you want to have a nice smooth glossy result after the topcoat. I assume you are trying to avoid nasty isocyanates. That's commendable if you don't wish to go to the extra expense of a supplied-air breathing system. The PPG OMNI MP181 that CNKS mentions would be a good choice for you for a surfacer product. Alternatively, DuPont's 131S, Fil-N-Sand, would also be appropriate. As has been brought up previously, this is not a PPG or DuPont promo site and I am not a shill for either company. I only mention these because I have used them in the past personally, am familiar with them and can verify they work. I now use a hardened surfacer (isos), but I also have supplied-air breathing equipment. What you want, in order to avoid isos, is a lacquer-type surfacer, sometimes just referred to as an acrylic surfacer or acrylic primer surfacer. They are fast drying products that do not require a hardener additive. If anyone else knows of such a surfacer from another company that they have had experience with and can recommend to you, I encourage them to do so. Relative to body work: Your local fellow's suggestion was entirely appropriate. That's how I do it. There can be a legitimate difference of opinion as to whether to apply body filler before or after epoxy. I prefer to apply it after epoxy because I usually want to get the epoxy on as soon as the bare metal is ready for it. I suggest you do any rough metal work, like banging out dents, etc. prior to any epoxy. You should strive to get the metal as close as to where it should be within at least 1/8" and preferably within about 1/16". Apply the epoxy and then the plastic filler. Once you begin to sand the filler down, you probably will cut through the epoxy to bare metal in some areas around the repair area. That's OK. Just spot the area using the Preval and some more epoxy and continue. I would apply any plastic filler within the time window of the epoxy (3 days after initial application with 170). BTW, for the sheet metal that you are going to use a surfacer on, if you can apply the surfacer within that window of the epoxy, I'd apply two coats of epoxy right off and then apply several coats of surfacer. You can sand the surfacer later, even months later if you want, without wholesale reapplication of the epoxy. Regarding the epoxy, if you get the 170, don't forget the required MP175 catalyst that is used with it. The tech sheet is for the 170 is here. You can now get it in three different colors but I prefer the standard gray. Note the 15 minute induction period. That means that you let it set for about 15 minutes after initial mixing before appling it. Stir it well, both just after mixing and again before application. Also note the pot life of 8 hours. After that time, the mixed product will not be usable. The following day it will be like jello, so don't mix up more than you think you will use at one time. I also suggest you pick up a dedicated wax and grease remover. I use PPG DX-330 but there are others. Here's a good description of how to properly use those products, which is not always indicated on the can labels. You should be able to get a Preval at the same place you get the 170. I've also seen them in some auto parts stores. Don't become discouraged if you wind up having to apply plastic filler or a surfacer product multiple times. That's usually the case for me. I never seem to get it "good enough" the first time. Don't try to fill rust pits more than a very few thousandths deep with a surfacer. Deeper ones require special attention or you'll be there forever. On your sheet metal you should strive for getting the smoothest possible surface. It needs to be nearly glass-smooth because any little imperfection will be magnified once the color coats are applied. Obviously there may come a point where you just call it quits and paint it. That happens to me and for a working tractor there's absolutely nothing wrong with that. Remember the fifty (or is it 20?) foot rule: From 50 ft away, most anything will look good. If your's is going to be a working tractor, you probably don't care about others critically inspecting it close up. I've been very pleased even when my result is something less than I would like it to be. Don't get hung up on perfection. It's not somebody else's Mercedes and you have only yourself to please. Your first paint job is a learning experience so treat it as such. Rod
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