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Bondo+Hardener ratio

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Daves69Coupe

Member
Im going to be finishing the patches on my fenders this weekend and I was hoping someone knew the bondo to hardener ratio. Ive searched on the forum and also on yahoo and didnt find anything that said the actual ratio. Im gona be using 3M bondo, just gotta pick up the hardener now.
 
Not sure about 3M, think they all mix about the same. Golf ball size bondo to an inch ribbon of hardener, check the directions to be sure.
 
There's no hard fast rule. It' s a bit of a learned thing. I try to mix it so that it is setting up about the same amount of time it takes to spread it.

Make a couple of small batches to practice. You want to avoid having too little hardener, it will not dry and you'll be redoing it.
 
Basic rule is drop a glob of filler so it lays out kinda like a pancake and run a line of hardener across its diameter.
 
wish I had the new 3M dynamic mixing gun, they gaurantee always the right ratio. I saw it on Stacey davids show a few weeks ago.
 
Seems like you may be over stressing about this one. While it is important to get a good mix ratio, it is not that critical if you are off a bit. Do as suggested and mix a couple small amounts up to get a feel for it and understand open times (hardening). Really, if it were that sensitive the directions would include measuring tools, etc.
 
I just realized something. You should be more concerned about my team kicking your butt this weekend in the football league than mixing up some bondo! :vic
 
"Horseplay" said:
Seems like you may be over stressing about this one. While it is important to get a good mix ratio, it is not that critical if you are off a bit. Do as suggested and mix a couple small amounts up to get a feel for it and understand open times (hardening). Really, if it were that sensitive the directions would include measuring tools, etc.
Click to expand...

Ambient temp and humidity are factors too.
 
Not hard at all, just don't mix with too much hardener as it will dry before you get it all on. Also, too much hardener will tend to crack sooner with time.
 
I have always heard the golfball size:pea size ratio although in practice that seems alittle light for the catalyst. I have seen Bondo that has been on the shelf and subjected to changes in temp go bad where the activation time is lowered and will harden quite fast, like less than a minute. Have seen this with Dolphin Glaze as well.
 
just go do it. it's pretty hard to screw up.

when it kicks, it kicks. so when it gives you that indication, stop spreading or you will create a mess that you'll have to sand back down.

there are more important things to worry about like surface prep and what it is you're using it for.
 
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