Well - after 15 frustrating minutes in the archives…
Can anyone hip me to the weight ratio for RR epoxy - I just got a scale for small batches, but can’t find the info…
Thanks -
i think theyve a sheet wit that info on www.resinresearch.net
otherwise greg loehr should be able to tell you.
Finally found it!
Plus a long ass diatribe by Dave Parmenter from four years ago… Is that why people laughed when he went “pop out?” Ha! I wonder if that means he thinks epoxy is ok now?
peace
Yo Taylor O,
Why bother to weight the stuff? Just take a small container full it twice with resin and once with hardener. For small batches I just use a standard stainless teaspoon or tablespoon and wipe off with a paper towel for the next use. The paper towel only lasts for about 10 batches but the spoons will last forever. If the batches are a little bigger just use Dixie cups of an appropriate size.
I’ve yet to have failure. I just spell epoxy differently than you.
No Worries, Rich
Halcyon, good tip. I have avoided trying that as I was afraid that what clings to the sides of the container would throw off the measurement enough of the “second” measurement to potentially kill the batch. Nice to have some report 1st hand
Get a scale. Use it every time. Volume method is possible, but vastly inferior. Use the most efficient, foolproof method available. I’ve done over 700 epoxy glass jobs in the last 2.5 years, start to finish. The scale. Ignore anyone who says otherwise. On this point, I know what of I speak. I’m not puttering on one malformed piece of crap in my garage for a couple of weeks here, but serving many very well known, demanding shapers and their customers. Do yourself a favor and scale up.
Agreed. Preferably digital and accurate to a tenth of a gram.
The mix ratio by weight is .45 : 1.
Hey Halcyon - Great idea… I even have a set. I found a little digital scale (Drug dealer refuse is my guess), and I don’t even know if it works, but I’ve often thought about it for tiny ding batches, so, if the scale is bunk, then I’ll go that way. I think I bumped the ‘e’ on the way to the ‘y’ - and didn’t notice till it went up… Ha!
Bambam -No offense, but I’ve had fine success with measuring batches by volume, never had a bad one, but I do get nervous eye balling half/quarter ounces. I do appreciate your enthusiasm - esp. in light of production. I had a job in a lab once, and use a scale for all the time for everything… all formulas were done by weight only, but we had more than two ingredients.
When I get around to buying batteries - I’ll report back.
In the mean time, I just took my latest blank out of the glue up clamps, and it looks sweet… The stoke continues!!!
Viva la Sways!
It is my understanding that mixing epoxy by weight is the best method to ensure all the molecules of hardener (B) bond to the resin (A) molecules. Any molecules not bonded are just floating around and not doing their job.
That’s also the reason you mix epoxy thoroughly - to make all the molecules hit one another to pair up.
There’s the extent of my chemistry experitise 
But, in all reality, how critical is a perfect (or close to perfect) mix anyway? I bet you can’t tell the difference between a surfboard glassed with a perfect mix of epoxy vs. one that is off by a few percent…
~Brian
As a person who manufactures resins and makes over 300 kinds of epoxy I can not stress how important the scale is.
Yea, people do it with out a scale but very few epoxy systems are exactly 2:1 ratio even if stated so. This becomes so important as your measurements become smaller. Even if your epoxy goes off and you think your system of mixing is right. You are not getting all the highest properties of the resin and critical things like heat distortion values, and key strengths are not where they should be.
Other bad things that happen by mixing by volume are bad sanding and hardener rich mixes that cause early yellowing. Surface tension problems that look like contamination are also common. Deck hot coats are the most easy to see this in when the epoxy is not going off and gravity has it’s way with it. The fish eye issues many get are from surface tension. Epoxy wants to be a certain millage and when it gets to thin and starts falling off the board it will want to find the right millage thus creating the fish eyes even if the surface is contaminent free. Adding solvent based additives in high heat can also cause these problems as well.
An other thing that people take for granted, most companies depend on the consistency of there raw suppliers. All though they try there best sometimes there is slight differences between batches. This why one hardener from the exact same company may look different than one in the same can or bottle next to it (more or less yellow). So they are not even consistent by weight and volume by the raw supplier. By weight is the standard for getting the most accurate measuring. That said, your volume will vary when you measure by weight. Get it. The chemistry is in the weight not the volume.
I recently did comparisons and to give you and Idea at 30 oz. measuring by volume your mix can sometimes be off up to almost 2 oz. off by weight. That is insane. So if you are one of those guys who mixes by volume and you have weird s%&t happen to you once and a while with epoxy and your scratching your head as to why it is happening. Start there.
Best of luck. I am sorry I do not no what Greg’s stuff is by weight. It should say on the label.
Well… Some more good info… The scale was crap, but after reading this, I may have to go looking for another one…
Thanks to all for sharing -
Hey Matt,
Thanks for clarifying importance of measuring epoxy by weight. That should help a lot guys who are looking to make the switch from poly to epoxy.
I now use a scale for every measurement and the results ARE noticibly better than measuring by volume.
~Brian
Calculate your .45:1 ratio.
Put the container on the scale.
Tare the scale to zero.
Add your resin and hardener.
Viola.
This GREATLY reduces your chance of a bad batch when doing those 100ml or less batches for fin plugs and repairs.