How to?

I got some old tractor fenders the are dinged and dented, but could be worse. I want to pound out the dents and fill in the dimples, then prime and paint.

I'll be using a HVLP spray rig.

What filler is best to use? What sort of tools do I need for getting the dings and dents out?

What is the best way to fill in pitting on sheet metal?

Sounds elementary- but I'm new to it, and figure some of you here would be willing to lend some tips on how to get it done.

Thank you,
Mike D.

My own suggestions follow:

1. Bang out the dings and dents carefully from the backside using a ball-peen hammer. A general purpose dolly helps some here on curved surfaces. Try to get everything to within about 1/8" of where it should be without any high spots exceeding the expected final surface. Peabody's post about the tube of sand seems like an excellent idea...I'll have to try that out.

2. Clean and degrease all surfaces with a specialized cleaner such as PPG's DX 330 wax and grease remover or similar. Scuff sand all sound paint that is to remain, if any, with 220 grit paper.

3. Sandblast rusty areas if possible. If not, use a power wire brush and/or sander with 80 grit to remove as much rust as possible, if any. If any rust remains, especially in the bottoms of pits, use a rust treatment such as Permatex Extend or equivalent. I have found it easier with such a product to use a foam roller rather than a brush. It's difficult to avoid brush stokes with this stuff. If you have only light flash rusting, a phosphoric acid treatment would be advisable in lieu of this method...but that's another case.

4. Do another wipe with the DX330 (or similar) and prime with a 2-part epoxy primer such as PPG OMNI MP 170 or equal. Be sure to observe the required time windows with this type of product.

5. Use a polyester plastic filler such as those by Evercoat or something similar to fill in the low spots (not the rust pits). I happen to prefer the smooth variety without the fiberglass strands. Level with 80 grit sandpaper. You may need several applications to get smooth. Use a long flat board as a backer towards the end here to assist in making it smooth.

6. For the rust pits, it depends on their depth. If over, say 0.005", I would use a flowable polyester finishing putty such as that from 3M or equal. This is simply a runnier version of the plastic filler above. If the pits are not deep, say less than about 0.005", I would use a lacquer type putty such as this from 3M. Use a rubber squeege here and give the lacquer stuff PLENTY of time to fully dry.

7. Sand everything with about 220 grit paper...by hand or light power with an orbital sander if you have one.

8. Do another wipe with the DX330 and give everything a final overall coat or two of the same epoxy primer as above.

9. Beyond this point the products to use (including hardeners) would depend on respiratory safety matters (and cost). Do a search in this forum on "isocyanates" for previous discussions on this important issue.

Rod

I picked up a tip here about filling rust pits. Use a product called Kilz in a spray can. After stripping the metal down to remove rust and/or paint, use a body filler to repair the large defects. Then, spray the Kilz on to fill the pits. It goes on quite heavy and makes a great pit filler. Sand the piece back down to bare metal and repeat the process until the piece sands smooth. Then prime. Worked great for me.

Good luck!

I picked up a tip here about filling rust pits. Use a product called Kilz in a spray can. After stripping the metal down to remove rust and/or paint, use a body filler to repair the large defects. Then, spray the Kilz on to fill the pits. It goes on quite heavy and makes a great pit filler. Sand the piece back down to bare metal and repeat the process until the piece sands smooth. Then prime. Worked great for me.

Good luck!