Need ideas: Filler loading sandpaper

[rkarr]

Hi guys, I need help..
I'm finished with the chassis, and I'm on to the bodywork.. I'm doing the firewall so I can get the cab back onto the frame to fit panels, etc...

I've got issues with the filler loading my sandpaper almost immediately while block sanding... Very frustrating.. Any ideas to help keep the paper clean so it'll continue to cut?

I'm using evercoat lightweight filler...
Thanks for the help.

[Sweet72]

I've used evercoat lightweight filler and blocked it out with aluminum oxide paper . Start with 80 grit and work your way down to 220. Is the filler hard enough or are you sanding it while it's still gummy?

[72CSTC5]

Start with 40 grit while your filler is "tacky" to shape your bodywork quickly before it dries completely. Let it finish hardening and then sand some more with 40 grit and then add another coat and block that with 80 grit first again while tacky and work the area again after hardened. Try to finish your bodyfiller with 180 before you primer if possible. Blow your paper off with a blower and compressed air to keep your paper clean. Good luck.

[rkarr]

Thanks for the input!

I ran the "cheese-grater" over it while it was still somewhat soft to shape it, but this has been sitting overnight and isn't sticky at all. I'm quite sure it's fully cured....
It doesn't seem to matter if I use 40 grit, 80, 120, etc., it still just loads up the paper immediately... I was wondering if anybody had any tricky "lubrication" ideas to help the paper last a bit longer. I thought I saw somewhere that someone was using bar soap on sandpaper, but I doubt it was for this application..
Any other ideas guys?
Thanks again.

[TugOwar]

Is it possible youre not mixing in enough hardener? Maybe even though it is fully cured it's not as hard as it should be. Just a thought.

[gator2511]

Use wet or dry paper and dip it often in a bucket with some water and a little dish soap in it and it will stay cleaner longer.

[Sweet72]

Are you stirring the filler in the can to mix all the polyester resin in? If it sets awhile the resin comes to the top and will load up your paper. Just an idea, try some talc or baby powder on the paper before you use it and blow off like 72CSTC5 says...but I wouldn't use bar soap as it may leave a residue that won't be easy to remove for priming. I don't think wet sanding is something I'd do on filler, it may absorb water and cause future problems with your paint job, but what do I know.

[rkarr]

Originally Posted by Sweet72

Are you stirring the filler in the can to mix all the polyester resin in? If it sets awhile the resin comes to the top and will load up your paper. Just an idea, try some talc or baby powder on the paper before you use it and blow off like 72CSTC5 says...but I wouldn't use bar soap as it may leave a residue that won't be easy to remove for priming. I don't think wet sanding is something I'd do on filler, it may absorb water and cause future problems with your paint job, but what do I know.

This is likely the problem.. I didn't stir the can beforehand.
Thanks again for all the help!!!

While I can't wait to have this truck on the road and be able to say I did it all, I'm beginning to wonder if the right tool for bodywork may be a check!

[72CSTC5]

Do not wet sand your bodywork, especially if you apply it over bare metal. The water will rust the metal underneath and come back to haunt you later. The technique I was telling you to sand the filler while it was still tacky was to cut it quickly just like you would with a cheese grater, however, most cheese graters dig too deep in to the filler and are hard to block bodywork smooth with. Try my method and you will see how fast you can do bodywork and how flat you get it. I am only 34 but have shown several older bodymen that work for me this technique and love it now. Much faster and flatter to start with.

[Southpa]

I've done work on quite a few guitars , a few cars and a few large yachts. You sure learn a lot of filling, sanding and priming tricks along the way. There are a few reasons why your paper is loading up and a few ways to remedy the situation.

Give the filler what we call in guitar building world "the fingernail test". If you can dent the surface with minimum pressure using your fingernail then its not ripe yet. ie. not ready for sanding. It may seem ready because its dry but it has to be cured to get the best results. If laid down thick you have to expect longer curing time.

Another reason for material loading on your paper is the actual sanding method(s) being used. Pressing too hard and moving too fast causes heat from friction. This will soften the finish and cause it to stick to the paper like s**t to a blanket. I'm sure you guys who have changed a baby before know what I'm talkin about. Let the paper do the work. Use less pressure and take your time. This is one of the most important parts of a good paint job anyway.

The idea behind wetsanding is to keep the heat down and carry the sanded material away. Paper lasts much longer and its a more effective method but it has its applications. As mentioned, not applicable here. I've had the odd problem with wetsanding a clearcoat on a maple or mahogany guitar. Water can seep into screwholes and swell the wood if I'm not careful. Its best for totally sealed surfaces.

Go buy a cheap 2" paintprush with those plastic bristles and cut the bristles down to about 1" long. This is a handy tool for cleaning your sandpaper now and then. Sometimes you can't avoid loading but at least you can minimize it. Its a real drag to see those striations in your finish because you weren't paying attention.

[shifty]

just FYI - the soap in sandpaper trick works really well with aluminum, but never heard of anyone using it on anything else but a soft metal.

[local13hutch]

I use a wire brush to clean my paper. Just be carefull. But it sounds like there is more going on here than just loading up your sand paper.. ''Good Luck''....IT sounds like the other members have pin-pointed the problem.....

[gator2511]

I never had any problem with the water and wet sanding. It might have something to to with the fact I was working on Corvettes.

[Sequoyah]

I was wondering if you could use a "stearated" sandpaper. I use it for woodworking for sanding in between finishes to "level it out" before I apply the next coat. It doesn't load-up as quickly as regular sandpaper. I dunno if that would work...just a thought.

[John Fabris]

I take a cloth with laquer thinner on it, and wipe the bondo down quickly before I start to sand it. This seems to get rid of the tackyness that was loading my paper down. One of those old timer tricks that a local painter told me. Don't know if it will work for everyone, but it did for me....