I agree with the evercoat fillers. I use rage gold or rage extreme.

But yes they still lose adhesion on 80grit steel. Maybe not every job but it does happen. Proper cleaning the metal will help you too

as Scott said above all I use is 80 grit but you need to watch and change it when it stops cutting, dull paper causes more harm than good. you should have no problems getting a good feather on bare steel. maybe you got a bad can of filler and or catalyst. I'm currently using USC PRO7 and like it, also use Martin Senior 6378 witch I believe is Rage. might be time to try a different filler, what do you pay for your 3M filler? I do like to wipe the surface with wax and grease remover the solvent type. I will go over the surface with an air hose and a clean rag, rub with the rag and blow it off with the air hose. then wipe with the wax and grease remover as many times as it takes to get a clean rag.
Jay D.

ScottB wrote:Decades in business, now primarily restorations and never had an adhesion problem with filler over 80 grit orbital scratch. Newer quality fillers have superior adhesion qualities compared to the mud thirty years ago. I use Rage Ultra.

Read the TDS for your epoxy if using filler over it.

Charge more for your work to include all material costs. You are polishing the surface with worn out paper instead of creating proper scratch. When paper becomes dull, I toss it.

Im going to experiment more on the next one and hopefully get better results, thanks

I agree with some of the others, 80 grit seems kind of iffy for adhesion. I always use a 36 grinding disc to prep the repair area for filler.

80 grit is fine, it's on the TDS. http://www.evercoat.com/images/ePIM/ori ... 015_EN.pdf
If filler is falling off 80 grit scratches, something is not being done right.

yes 80 grit is on the TDS.
according to most TDS sheets you can let your basecoat sit for 24 before topcoating with clear. do you know how many lose their clear due to this TDS based instruction ?

also another flaw in TDS sheets in the can apply over "sand blasted steel" instruction.

most coatings require a certain blast profile much deeper than most people care to learn about. TDS sheets are put out there with very little information on them to be honest. i train every 2 years with PPG and first thing they do is tell you throw half of your TDS sheets in the trash.

my advice after 27 years in the custom industry would be to use something coarser than 80. if youre going to error do it on the side of caution and have peace of mind knowing the next guy that gets that car wont be asking why the filler is not sticking.

I own cars and have exposure to cars I repaired and restored, some 20 years ago. None of my filler is falling off and I've never had a comeback due to loss of adhesion.

If you sand metal with 36 grit, what do you do if you sand the filler with 80 grit and need another pass? You guys must be chasing all metal adjacent to the featheredged filler with 36 grit all over again before spreading another coat. You are certainly reducing the 36 scratch with 80 grit after sheetrocking a panel and sanding three sessions of filler.

i usually 36 grit and lightly grind the steel. yeah scott i agree with you buddy. I have repaired a lot of cars over 27 years that are absolutely amazing and look very well done and have held up for years i also do a lot of harleys and one of the biggest problems i run into is when im stripping a set of tins or doing a repair on a car when i get to the filler underneath it does not feather and the edge just chips away. i can also slide a piece of paper under the feather edge at times. the bondo seams from the outside like a sound repair but maybe over time has collected moisture or lost some adheasion. whatever the case the filler will not feather and has to be removed. any how i believe everyone to be right in this thread. its just my opinion.

I think many people have their DA cranked up and are overtsanding to the point of eliminating scratch, not to mention being cheap by stretching paper longevity. You can't get any tooth when sanding metal with marbles. Same principle applies to panel adhesive. Even though it is on the dreaded TDS, the fact that they stress to provide proper tooth by not overgrinding carries weight.
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When prepping a repair area, I grind off paint beyond the repair area at least a couple of inches depending on the size. Spread filler into damage metal extending it out beyond the repair area. Next I block with 80 grit air file or file board to shape filler and feather edges into surrounding metal. If the repair needs extra pass of filler it is usually thin and very rarely extend past the edges of the original pass. Next is skim coat of glazing to fill pin holes and deeper scratches left by grinding. I Don't think you get the same cut with DA as you would by hand sanding with 80 grit.