Bondo.....

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pishta

I know I'm right....
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WTH? I mixed up a small 3" round x 1/2" pad of 3M Bondo and mixed it up with a 3" stripe of hardner as described in instructions. Mixed it for about 2 minutes and by the time I was slapping it onto the dent it was not even spreading anymore, just clumping and way harder than I remember it. Whats the official ratio of hardner to filler? I got a scale and will use about 3/4 the hardner called for next time for some longer set up if that works. Im putting it on a horizontal surface so I can have it a little runny as long as it gets into the screen. Im patching a 3" rust hole (double wall, top is rusted through) in my little beater truck.
 
It varies with temperature and humidity. I find that it is a pretty wide ratio with a LOT more filler than catalyst. Colder weather means a LOT slower setup, just like concrete.
Next time, consider a better body filler like Rage Gold. Most fillers will shrink a bit over time but Rage seems better. It spreads and sands better too.
Funny aside.....
Years back I was doing bodywork and popped the cap off of a BONDO can. Inside was the catalyst and an offer to get a FREE red BONDO jacket with proof of purchase of 10 of their 1 gallon cans. I laughed at the thought of the guy at the car show bragging about his car while wearing a jacket that shouts just how much body filler is in his car! You might as well wear a Preparation H jacket or something equally humiliating!
 
80F here, $12 to fill a few holes and VatoZone was skateboard distance so.......I remember paying 2 guys $100 in 1991 to fill all the dents on my 57 Ford Jalopy. I dont think they use any hardener as the gray filler was still fingernail soft after a week! :BangHead:
 
You only need a little bit of hardener. Plop a round blob on a mixing board and then the hardener you mix in should be a line about 1/4 the diameter of the blob of filler.
 
Some fillers harden pretty quick now. At least the stuff i got from the body shop. When it starts to tighten up, its done. Golf ball size glob, 3/4” strip of hardener.
 
says 3-4 minutes mix/set up time, man I though it was like 10? not a deal killer, I just ended up putting 3 coats on it. **** is hard as cement to sand manually. Well see tomorrow.
 
says 3-4 minutes set up time, man I though it was like 10?
No, not 10. Maybe white lightning from 30 years ago.
Not much working time, so mix smaller amounts or move faster.
 
Just mix the bondo with the hardener until the colors are all mixed together. You have about a minute from that point until you can't work it.

A squeegie for mixing, cardboard for the mixing board. Why spend the money on the mixing paper board if you aren't doing repairs constantly? I just used cardboard scraps when doing repairs on drones.
 
last bondo job I did was in high school auto shop...1985! All my cars have been straight, that's been a prerequisite as I'm no body man!
 
I always go with "around" a 3 to 1 ratio and it works fine.
 
hold up, 3:1 as in 3 inch filler puddle to 1" hardner squirt?
 
It varies with temperature and humidity. I find that it is a pretty wide ratio with a LOT more filler than catalyst. Colder weather means a LOT slower setup, just like concrete.
Next time, consider a better body filler like Rage Gold. Most fillers will shrink a bit over time but Rage seems better. It spreads and sands better too.
Funny aside.....
Years back I was doing bodywork and popped the cap off of a BONDO can. Inside was the catalyst and an offer to get a FREE red BONDO jacket with proof of purchase of 10 of their 1 gallon cans. I laughed at the thought of the guy at the car show bragging about his car while wearing a jacket that shouts just how much body filler is in his car! You might as well wear a Preparation H jacket or something equally humiliating!
Hey now.. I wear my Prep H jacket everywhere I go and the people say I look "slick" and "bad ***" in it... I just wish I could get the chilli stains off it..

Lmao
 
More like 10 to 1.

painting-101-understanding-plastic-fillers-2019-02-19_02-36-45_956999-960x768.jpg
 
Hey now.. I wear my Prep H jacket everywhere I go and the people say I look "slick" and "bad ***" in it... I just wish I could get the chilli stains off it..

Lmao
I bet that's a "members only" style jacket too.
Very cool.
Lol
 
Too much hardener on a hot day.

So you had 3 times the amount of recommended hardener.

The hardener (like peroxide) is the catalyst that makes it dry.

At 80° the catalyst Works 4 times faster than it does at 65°.

If your mixing Board is hot from sitting out in the sun, that speeds up the reaction time by 10 fold too.

Good luck. When you can scratch the bondo with a finger nai and it leaves a white scratch. That is the time to start working it before it gets super hard. Like hitting it with 36 grit on a sanding Block to bring it to shape.

Then when to shape let it fully harden, and final sand with 80, and 180, feather edge the area and it's ready for primer. Then block sand that.
 
@George Jets That's the thing, I used the hardener exactly as stated on can. I just remember it setting up much slower. Maybe it was the heat as I had Autoshop 2nd period and it was still pretty chilly in that massive garage. Still got over half a can and 2 more holes to fill so Ill get it 'right' one of these times.
 
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