Mix resin/hardener by weight?

denpo

denpo

Carburated Nihilist
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Jul 14, 2010
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Montreal, QC
I'm practicing fiberglass on a side project for my wife and once again I got a batch that didn't cure correctly, that was close, but not enough.
I don't have fancy tool for measuring liquid but I got a precision scale (up to 1kg by 0.1g increment).
I though I would be more precise putting the right amount of hardener this way.
I'm using the common 3M bondo resin and I couldn't find any mix-by-weight instruction.
Is that feasible?
 
over the years I have never had resin that didn't cure. it takes longer and might require a hair dryer to add some heat but the resin has always cured.... i dont use a scale to weigh it, a few drops and it'll be fine, never mix more than you can use, it cures rather quick, especially in FL heat (90's)...
you just need to develop a "good feel" for it, as difficult as it sounds, once you have the resin cure it the cup you know how muh hardener is 'too much'......
 
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Weigh epoxies (resin and hardner) and get the percentages right and you'll always have a good mix and cure.:thumbs:
BTW for us in the Hot zones (FL/Lower ALabama/Texas) don't forget you can chill the resin in the fridge to slow your cure times - gets a bit Thixotropic -- That's Stiff GENE! (just checking if he's reading these>>>):fishing:

Cheers - Jim
 
the bondo type resin hardener is quiet difficult to measure, especially if you only need a little... if you need to add like five drops of hardener how do you "weigh" it ??
it is a lot easier if you use products that have to be mixed 4:1 or 2:1
 
If you're using polyester and mek as a hardner, the easiest is to use a large graduated measuring cup (only a couple bucks from paint supply) and a syringe for the mek. You can also use the drip method for the mek. Download the charts for temperature/ratio etc.

If using epoxy, the easiest is to use the hand pumps on the jugs, since with epoxy, there is no leeway. Pumps here are only a couple bucks apiece.

I only ran into one bad batch in 40 years and they replaced it after testing.
Be aware that polyester resin does not have a very long shelf life and chances are high that it's old, depends largely where you buy it. Find yourself a boat repair/builder and try to buy from them.
 
Guys, you're just confirming was I was thinking, the weight differences are just to big to get any good reading.
Yeah the resin was probably not that good anymore.
Hopefully when It comes to the vette I'll get epoxy resin from a specialized shop, maybe SPI if shipping is not outrageous.
Thanks for the inputs
 
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