The Stovebolt Site Forums The Shop Area Paint and Body Shop bondo question

First, there are a couple of places on this one piece that has been sitting for like 3 days and I can touch the bondo and run my finger across it and it's still gooey feeling... that's caused to not enough hardener mixed in, right?

Blake,

You hit the gooey nail on the head! I don't think it hurts to mix bondo heavy on the hardener.

Stuart

Blake not only does it not hurt to mix the hardener a little strong, but it needs to be mixed very well to ensure that all the bondo will cure evenly.

Your progress looks great, i look foward to seeing more.

Evan

I figured it out... this is the first time I had worked with bondo, and it was the hardener that was doing it.. I got it right and since then, I've mixed a lot and repaired a lot.. it's turning out nicely now!

This can also be the sign of expired hardener- it does not work as well as the fresh stuff. Always mix up a small batch and stick it on something you don't care about when you start a new tube/can of bondo, just to make sure you don't have to take it off again.

when i was doing the body/bondo work on my truck in 1989 we had a cold spell and the bondo wasn't setting up as fast as i wanted so i added some extra hardener to speed up the hardening. Those spots that i used extra hardener on started cracking and coming loose in as little as 5 years. those spots that i followed directions on the bondo is still as attached as the day i applied it. sometimes it just pays to follow directions to the letter.

By adding more hardner to bondo not only does
it become non-workable quicker (hardens) it weakens
the bonding...and as someone pointed out will only last a short time...All hardener has a shelf life and becomes gritty...Toss it.
On My 52 while removing front fender, I heard something hit the floor..looking down, it was a 1 inch thick chunk of bondo that fell out from the front headlight area...to My surprise, there was a Budweiser beer can with the ends cut out, split and laid over the rusted area...It was not even held down by tape...Now, the person that did that needs a # 12 boot where the sun don't shine...BB

Too much and/or poorly mixed hardner will also result in paint bleed thru from the peroxide (main ingredient of hardner) especially the lighter color coats. Poor mixing can also result in pinholes. To make the filler set up faster just raise the ambient air temperature and if the panel you're filling is cold pre-heat to 75-80 degrees F. with a hair dryer or heat lamp.

i am with you bill - the po should have used a miller lite can!!!!!!!!!!!

I dunno...Miller lite tastes great, but is less filling!! Mike

Apparently you have figured out that three days is way too long for any thing let alone bondo. Hey we all have to start somewhere. Try to mix close to the manufacturers recommendations (it is an eyeball thing). Try to get out as much of the dent as possible. Work the bondo high to the center of the dent and feather to the edges when applying. If you are new to body work, when sanding, don't judge by the eye, feel with the hand. (Note that bare hands on sand paper will usually end in poor result).If you think your close, spray with gray primer and (mist or cloud over) with a black or a darker primer, sand with a sanding block or foam block. Your high and low spots will appear quite fast. If it is on a flat surface, use a sanding board (pneumatic) or a flat short board.
If you mix bondo with too much hardener it can crack and not to mention waste your money and time because it also gums and balls up very quick while you are trying to spread it.
If you have to fill a deep dent, IE: You can't knock it out or have no access to a dent puller (the kind you can mig a "nail" to the metal) is by far better than, the make a hole by attachment method. Conside dynaglass (green fiberglass filler). Do it in layers and allow for good cure times. The worst thing on any finish is bulging or popping of bondo work.

blue dot - you got me on that one!

I used to always mix it till it was pink, but there are two kinds of hardener, cream (oxide red color) and the clear liquid. I used to hang around a body shop and I never saw their filler looking pink, they used Martin Seynour (napa) "cuz" polyester body filler. Since you are supposed to primer bare mettal and As hot as it gets when you mix lots of hardener, I'll bet fresh primer and the heat causes the adhesion problem. Too much hardener makes it too hot to touch...just a thought.