Bondo hardener

[Cato]

Just got a new package of the Professional 2 part Bondo. It always worked great.

With this one, the small tube of hardener is mostly runny red/brown liquid. I mixed a small batch using the liquid and it catalyzed fine. But there's no solid paste unless I squeeze out the whole tube.

Any one else experience this? Did they change the formula??

[Longbox55]

Mine is like that, too. You really need to shake up/knead the tube before you use it. I've seen the larger tubes do the same thing.

[Harry P.]

Just got a new package of the Professional 2 part Bondo. It always worked great.

With this one, the small tube of hardener is mostly runny red/brown liquid. I mixed a small batch using the liquid and it catalyzed fine. But there's no solid paste unless I squeeze out the whole tube.

Any one else experience this? Did they change the formula??

The hardener does tend to separate. Like Bill said... shake and/or knead the tube before you use it.

[Chuck Most]

X3 on the shake and knead- that will pretty much eliminate the problem. I get a tube of hardener like that ever so often.

[Craig Irwin]

The tube clearly states "knead before using", but if you didn't "knead" it you wouldn't use it!

[Cato]

Thanks for the advice guys. Now I hafta read instructions too.............??

[Cato]

The tube clearly states "knead before using", but if you didn't "knead" it you wouldn't use it!

For the record, neither of my tubes have the 'knead' instruction on them. Only cautions for irritant, allergies, the full MSDS sheet, 'if swallowed' and danger of hangnails.

I'm going back to not reading instructions...

[jwrass]

Dump the instructions and Knead as the others have stated! This is a common task done in body shops on a daily basis. Hardeners are a mixture of benzoil peroxide and fillers (talc) the solids separate from the liquids and if not kneaded you can have (and I have had) dye back, pinholes and a whole host of problems. You need to Knead!!! That's the best poetry I have

[Cato]

I'm kneading, I'm kneading!

Just not reading, not reading!

[Ace-Garageguy]

... Knead as the others have stated! This is a common task done in body shops on a daily basis. Hardeners are a mixture of benzoil peroxide and fillers (talc) the solids separate from the liquids and if not kneaded...

Yes, but a couple more small points.

1) The most common "hardener" or "catalyst" used in polyester resins you'll encounter in Bondo or similar products is MEKP, methyl-ethyl-ketone-peroxide.

2) The best way to "knead" a tube of "hardener" is to hold it with the cap uppermost, tap the bottom on the bench to shake the contents down away from the cap, take the cap off and carefully squeeze the air out of the tube, re-cap it, and knead away. You CAN NOT effectively knead these tubes if they're full of air. This I know, as I've been using the stuff professionally for over 40 years.

3) Also, thoroughly stir / mix your filler BEFORE adding hardener. The liquid resin will separate out of filler too, over time.

Edited June 22, 2014 by Ace-Garageguy

[Cato]

Thanks Bill.

[Harry P.]

I just shake the little tube of hardener before I open it. Works for me.

[jwrass]

I too have been using these products for some 35 + years as a professional and Bill is right on! He paid more attention to the post and I assumed to much. Follow Bills directions and you should be good to go!!!

Thanks Bill for your detailed description!!! this will save many grief from filler failures. Jimmy Rass