The Stovebolt Site Forums The Shop Area Paint and Body Shop Advice on mixing body filler?

I seem to never be able to get filler mixed correctly. I usually mix up a glob about 1/2 the size of my fist, then squirt about 3/4" line on it from the tube of hardener.

I worry, I either get too much or too little. Do you guys have a better way?

Michae1964, As you get to using it more and more, all this will come to You...If You have a
large area to put bondo in, then that means you
don't want it to kick off before You get Your full
area covered....The less hardner you put in, the
longer it will stay workable and will be stronger also...the most important part of mixing is make
sure You have it mixed real well...You will also find hardener fresh off the shelf that is gritty.
It has a shelf life, don't use it, make them give You a new tube.... Bondo 1/2 as big as Your fist
should get approximately 3/4 " ribbon of hardener.
Bill B

Michael, almost forgot....always make sure You
kneed the hardener with the cap on cuz if You don't
when the lid comes off oil that has seperated will
squirt out...Must blend it all together...Bill B

Thank you so much!

if i'm using bondo i try to use the spreaders that are color coded to match the correct, mixed, color of the filler.

and as bill_b says above, i prefer slightly paler for better workability and strength.

whats with bogging the hole vehicle and then start and sand it of on Boyd Coddington is this what all body men are doing or what?

I have never known this existed, what a great idea. I seem to remember seeing a pale pinkish spreader that would be the same color as some fillers when mixed with a red hardener, that is a GREAT idea.

Brian

The pink color coded spreaders I have seen locally are Bondo brand. They are sold in a bubble carded package.

One trick I learned is to take your round blob of filler and cut it in half with your spreader, now two blobs = 50% of total, cut one in half again = 25%, again = 12.5%, again = approximately 6%, again is 3%, match your hardener amount to that last pile, or slightly less; that is to say 2-3% hardener to filler.

You also would ant to avout mixing too much up in one shot. When mixed properly, it'll "kick" within about 3 minuits, and unless you work fast, you end up with a half solidified glob of filler that's no good. I usually won't mix up more than about 1-2 tablespoons at a time. If I need more, I'll let what i put on set, then add as necessary.
Another tip is to keep from getting air in it as you mix. Getting air in it causes bubbles and voids in the filler that you will have to fix later.
One more thing. Not to put down Bondo, as it is a good product, but I personally prefer to spend a couple of bucks more and get the Dynatron (same company, better product)fillers. They're a professional grade filler, and sand out smoother and easier. They're usually a gold color instead of the normal pink, though Dyna-lite is the standard pink color. Auto-Zone and Advance Auto both have been carrying Dynatron, 'Zone seems to have a better selection, or at least in my area.

My filler says to use a 4" strip on a 4" diameter pile of filler. It also says 2-3%, but not how tall the 4" pancake is. I have had to throw out filler because it does get too hard to spread too quickly. Seems like that only takes a few minutes or less to happen. Am I using too much hardner or just mixing up to much filler? I did try about 3 or 3.5" strip and it didn't make much differance.

when its hot less harner is needed when working in a cold shop i use more hardner

just a tip Michael ,
find a pc of old plexiglass to mix on dont use cardbaord of anykind to mix on it will suck out the good stuff in the mix and make your bondo not so good .

Kemp...you thin coat the body and sand off to get all straight...doc

As you know, when the catalyst kicks in, it gives off heat. That heat causes next-door molecules to kick-off. Pretty soon, the whole thing is cross-linking, going through the reaction to turn solid. Smaller masses (globs of mix) will give off less heat, so the reaction will be a little slower. On the down side, you have to be more precise on your mix ratio.

I'm a poster child for Body Filler Amateur. I know the mechanics of it, but I haven't mastered the knack. Until I do, I'll continue to work with tablespoon-sized mixes on my bumper project. I find when I go golf-ball sized, I end up throwing out about half of it.

Bill

Couple of good links by martinsr at hotrodders:

http://www.hotrodders.com/forum/plastic-filler-tips-98890.html
http://www.hotrodders.com/forum/what-your-filler-primer-finishing-procedure-98800.html