Oops!

[nocheepgas]

I screwed up, but luckily not on a weld. I undermixed the hardner in some body filler, 2nd pass, and now have a mess. I scraped up what I could, but don't want to put down another coat until I'm sure it's all off, don't want to end up with uncured filler under my paint. Sanding resulted in a bigger mess.
What can remove the uncured filler?

[TerryL]

Acetone maybe?

[Fishy Jim]

Unless you really went low, the stuff should eventually cure. Some of the fiberglass surface curing agents might work too. The filler you used was polyester right?

[Blondie_486]

A Stanley shur-form file or as some call them a micro plane should get it off, of course you'll get some of the first coat as well but you'll be sure to get it all off. Most of the time though if it's just a little bit the next coat if mixed properly will cure what little remains. You can also use the surface hardner for fiberglass as mentioned before.

[nocheepgas]

Unless you really went low, the stuff should eventually cure. Some of the fiberglass surface curing agents might work too. The filler you used was polyester right?

It's been on there for 2 days, still soft. Yes, polyester, Marstons

Acetone maybe?

I'll try that

A Stanley shur-form file or as some call them a micro plane should get it off, of course you'll get some of the first coat as well but you'll be sure to get it all off. Most of the time though if it's just a little bit the next coat if mixed properly will cure what little remains. You can also use the surface hardner for fiberglass as mentioned before.

Not enough on there for a surform file, total thickness is less than 1/16".

[Fishy Jim]

1/16" is pretty thin. Try the surface hardener and maybe a little heat from a hair dryer or heat gun (just don't go too crazy).

[Fortyfords]

When using any filler keep it as thin as possible 1/8 inch thick max.
If you need more than that your metal work underneath is not good enough .
Work your metal out closer to the shape you need.

But back to your ?
Lacquer thinner or acetone will remove it.
I prefer lacquer thinner not as bad a acetone.
After its scraped with a cheese greater
Make sure all the chemical has out gased before appling your next coat or you will get solvent poping under your primer
Rich

[Fishy Jim]

If you need more than that your metal work underneath is not good enough .
Work your metal out closer to the shape you need.

Rich

The only bondo work I've ever done was grafting on plastic parts to metal ones. 1/4" and thicker in some cases - never had cracks even in the dead of winter.

It's not always about pounding tin.

[crawdaddy]

After you clean the bulk of it off with laquer thinner,dont forget to rescuff the area you are applying it to with 80 grit, the scratchesleft behind is where the bondo gets its adhesion. BTW most body fillers cure much better at 60 degrees F and above.Mike