Prime before bondo?

It all depends on the type of filler you are useing. Some must go to bare metal and there are some that will only go to primer or sanded paint and there are some that will go to both.

I primer first. That way, you help prevent any rust from coming back up, and it also helps prevent the bondo from taking in any water, which will cause more rust.

Well is the correct thing to primer bondo primer? that would seem to be the best thing to do in my mind.

I'd use it on bare metal. Then primer. Bondo is a sponge, and the moisture will be coming from the outside, not through the metal. Unless you have a big ass hole there all the way through to the other side. In that case, Bondo is just a big fubar waiting to happen.

I believe them to be equal. There may be newer bells and whistles with the additives, but basically they are just a filler or a leveler. If done right, they can be an acceptable form of body work. But in the hands of a shade tree amature, they are a hat trick.

To start off, Bondo is a brand and the generic term for filler. There is a difference amoung them. The main difference is the staning. Most of your high end fillers are stain free. That means that they will not stain. Cheap fillers have the chance of staning. That is where you see stains in the paint from the filler, no primer or sealer can stop it. If something stains from the filler you must remove the filler and start over. Its mostly seen in white and other lite colors. Like I said it does not happen all the time but there is a chance. Now the higher end fillers are stain free and yes they are higher in price. Most go from 18 to 25 a gallon, and they do say stain free. Todays fillers are very durable if used right. The fillers with metal chips in them are very good fillers but they are much harder to sand and price is around 70 a gallon. As for the primer-filler-primer thing in some cases that is good but most heavy fillers must go to bare steel, the directions on the can will tell you. You can still primer your car but places you need to put filler just grind the primer back off. If its just light dents that you are working with some lightweight fillers will go to primer you can just scuff the spot that needs to be fixed and just apply the filler to the spot. In the end all filler needs to be primed you really should not seal or paint over bare filler. As for primer stopping rust, if you take a part and strip it down to bare metal and let it set out in the rain and elements it will still rust, you may not see it but primer is porus. Now if you take a part down to bare metal and primer it and it stays in you garage and does not get wet all the time you are good. If you are doing an restoration and have something sand or media blasted when you get if back you need to get it in primer as soon as possable the primer will help surface rust. And that is where the primer filler primer thing comes in. If your vehicle is in primer it somewhat helps to see the dents, so depending on what type of filler you are useing you can grind the primer off and apply the filler and then reprimer or you can just scuff and use a filler then reprimer.

I don't have any personal experience with painting cars. I have always heard that you should stick with a single brand, if at all possible to ensure that all of the products work well together. It might be a good idea to check out the different auto paint suppliers and see what they recomend.

63_Fairlane said:

I don't have any personal experience with painting cars. I have always heard that you should stick with a single brand, if at all possible to ensure that all of the products work well together. It might be a good idea to check out the different auto paint suppliers and see what they recomend.

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Yes it is very recomended that you stick with the same brand of paint. Back it the day most of the stuff was about the same but now days. I have seen it done with no problems and I have seen problems. With the cost of paint these days one would be foolish to play chemist with different products.

Z Grip right to the metal - just make sure the metal's scuffed (DA works fine). As far as paint, stick to the same brand and you'll be OK. For example, use a PPG system. Spray sealer onto bare metal, then prime. A good high-build primer is the way to go.

lauras70mach1 said:

, Spray sealer onto bare metal, then prime.

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You must be careful with this there are very few sealers that will go to bare metal. And there are not a lot of primers that will either.