Just like the title says. The filler is still at the point where you can press your fingernail into the surface. I attempted to sand it and the paper clogged in a few seconds.

I am doing fiberglass work and using body filler on the low spots. Only problem is the Bondo is not hardening. I am sure I put enough hardener in the mix as the color is a color closer to the color of the hardener. I have let it sit outside now in the direct 90* sunlight for two hours yesterday and another two hours today.

If I need to remove the Bondo how do I do so? try the cheese grater?

 

Sounds like the hardener isnt any good. Does it appear to have a sandy or grainy look to it? How old is the filler? If its not an issue of too little hardener then one of the two parts have got to be no good. My bet is the hardener.

 

If your using the Bondo brand filler, throw that junk in the garbage!
I work at a large bodyshop, and we won't touch that stuff. My guys use 3M Keylite for general repairs. USC Duraglass where you need a high strength repair.
I've heard good things about Evercoat fillers as well.
The Bondo brand filler sands hard and is more prone to cracking.
It usually dries fine though, maybe you got an old batch?

 

You mixed in too much hardener.

 

One time I'm not sure how I goofed it but it took a week to harden but it eventually did. If you're patient it may be worth it.

 

I sounds like you will need to remove what you have laid down, If you are using bondo brand filler over fiberglass, I would suggest adding fiberglass resin to your bondo this is called a milkshake and use the hardener for the fiberglass resin, This will sand easier than fiberglass resin and bondo. and is easier to spread.

 

There are many reasons it could be happening,..... One of them could be moisture. The dew point has been near 70 around here for (what seems like) months and the humidity in the northeast this Spring/Summer is ridiculous. There is SOOOoo much stuff I'm not doing because of the moisture outside. ( sand-blasting, painting, bodywork, ect... ) I'm even getting concerned that my firewood will not be well dried next winter if things don't change - very soon. I don't know how it's been near you, but if the materials were 'set-up' when the air was wet; it matters !

There could be a lot of things causing the problem. I would scrape all the filler off, set-up again in the best conditions/environment possible, buy new materials from a different source,.... and get ready to 'start swigging' during round 2 !!!!

 

Thanks all, I eneded up buying a drywall sand paper, the kind that looks like a metal screen. I put that on a hand sander and took off almost all of it. It had started to dry and been maybe 95% dry but still not hard. I think the idea about humidity could have been correct. It has been very humid for the last month, especially at night. It wasn't an old batch unless it sat on the shelf at the store for long periods. Only other idea I heard of was if it had frozen, which could have been possible. At any rate it is sanding fine with the drywall sanding setup. Ill get all the Bondo off I can and start with a new kind. Thanks again.

 

Bondo brand filler found at Advance Auto, Auto Zone or whatever you have in your area is prone to be old. Most people don't buy filler from them so it sits on the shelf for a long time. That has been my experience anyway. OP's problem sounds like the hardener had separated and the liquid had leaked out. I've seen this before also. This would explain the color change but no activation. JMO

 

I would grind all that soft filler out,even if its hard on top. Bondo is junk. Evercoat gold is a good filler and evercoat glaze.humidity will only make it harder faster.im a bodyman and our doors are always open.last weeks was pretty swampy feeling in the shop

 

it sounds like you used to much hardner in the filler been there done that trying to speed things up you should have mixed it 10/1 if it were me I would go out and pick up a can of Evercoat rage or rage gold I use a lot of filler and this filler is the best I have used

 

I had the same issue with fiberglass filler with and without strand. It was also the Bondo brand. It never truly hardened. I ended up removing all of it and costed me alot of time. What I ended up doing was using fiberglass mat and resin and used evercoat product as both my filler and glazing putty. It makes more of a mess when sanding but the quality by far is much better and in the end will make for a better base. I'll never use bondo product again if I am every crazy to do another car.