Page 1 of 2

The Way to Measure Epoxy Mix

Posted: Tue Mar 29, 2011 4:24 pm
by BayouBengal
I'm using epoxy on a set of cabinets for an outdoor kitchen and decided that I'd give System Three a try. Looking through System Three's Epoxy book, it stressed the importance of getting your epoxy mixture ratio as close as possible to the ratio specified for the epoxy being used and suggested a digital scale is the only way to do this with any accuracy. You can buy one of these scales from Harbor Freight for $12 - http://www.harborfreight.com/1000-gram- ... 97920.html. Once you use this, you'll never go back to all of the marking and eyeballing measuring cups. This makes mixing epoxy so much easier, especially small batches.

Looking through some old posts, I found that Bob Perkins already told us this was the way to go.
I used a digital kitchen scale and measured by weight. NEVER a failed batch. Then just use plain old plastic cups from the super market. I used pumps for a while - but they tend to get clogged and gummed up over time.

I keep our scale in a plastic baggie so that it doesn't get covered in goo.... I actually use it in the kitchen.
It is much easier with 2:1 epoxy such as System 3. But if I used West - I would just print up a chart for the shop to do the math for me.

I often make 2-3 squirt batches. This is easiest with the digital scale.

I did make a 23' cold molded boat this way - so it works
good luck

Re: The Way to Measure Epoxy Mix

Posted: Tue Mar 29, 2011 10:18 pm
by leakcheck
That is a great tip. I started out using a scale. Got lazy..went to the pump. Pumps sometimes only put out partial delivery on first pump after sitting for a while...scale doesn't fail !! ..

Steve

Scale = no fail! :roll: :wink: :lol: :oops:

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 2:36 am
by fschonowski
I am a nurse, so I have access to syringes. The 60cc ones that are used for tube feedings in hospitals and nursing homes are excellent. I have built 3 boats using them. Mixing up a batch as small as 6cc[1/5 ounce] is even possible. Find yourself a nurse or nurses aide that you may know and ask them to get you 2 of them. Complete accuracy!

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 4:45 am
by lakeracer69
fschonowski wrote:I am a nurse, so I have access to syringes. The 60cc ones that are used for tube feedings in hospitals and nursing homes are excellent. I have built 3 boats using them. Mixing up a batch as small as 6cc[1/5 ounce] is even possible. Find yourself a nurse or nurses aide that you may know and ask them to get you 2 of them. Complete accuracy!
I use these as well. A Veterinary supply house is where I get mine.

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 9:23 am
by leakcheck
I tried those syringe thingys but I couldnt find one with a hole big enough to pour the epoxy in it. By the time I ever got a drop in one of them I had completely covered my entire hand and half of the table...it was just not efficient. Maybe if they made a little miniature funnel...

Steve
:roll:

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 9:35 am
by gstanfield
hahaha, you're obviously doing it wrong. The best way to put epoxy in the syringe is to pull the plunger out and pour the epoxy in the back side of the syringe tube, then you can use a slightly larger funnel :wink:

Geeze, some people just don't know how to do anything :lol:

George

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 4:24 pm
by leakcheck
Shoot dang ! ! ! Now ya tell me!! .... :roll: :wink: :lol:

Steve ...

PS...I really am Polish!

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 5:51 pm
by gstanfield
My wife (an RN) was reading over my shoulder when I posted my earlier reply. After I typed it she looked at me a little odd and then asked "Why not just pull it into the syringe like you normally would"?

I just smiled and said "exactly"

She walked off mumbling something about boats destroying brain cells or something like that :lol: :lol: :lol:

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 6:31 pm
by vupilot
Keep in mind some epoxy labels will state to mix by volume. My MAS states to use volume. I wonder if the weight is different between the resin and hardener and would throw off the ratio if done by weight?

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 8:39 pm
by leakcheck
George...she will figure us out eventually ! Let's keep her guessin till then!

VU...you might have a valid point there. Seems to me (this was a LONG time ago) when I was testing resin (polyesther and vinyl) we did our qc test by weight. But like I said...that was a while back...and surely was not epoxy!

Steve

Re: The Way to Measure Epoxy Mix

Posted: Wed Mar 30, 2011 9:05 pm
by raymacke
I checked with MAS. They said there was a difference between weight and volume but it was so slight it not an issue. Either method would yield good results. I used both. Volume (pumps) for small amounts and by weight with a balance beam scale for larger mixes. Never a problem either way. Here is a link to my crude but cheap and effective balance beam - http://egyptian.net/~raymacke/hints.htm . Had to move the pivot point for the 2 to one mix MAS uses.

Re: The Way to Measure Epoxy Mix

Posted: Thu Mar 31, 2011 2:02 am
by fschonowski
The tube feeding syringes have like a 1/4"hole in the tip. The epoxy can be sucked right up from the container with them. Even at 20 degrees outside, I am still able to use them. In fact I did use them for an enire winter in Maryand to build a 23' stitch n glue boat in a party tent. Sure resin has a different density than the hardener,therefore, a different weight per volume. Probably the case in most brands, but the difference is so slight that they all can be mixed by volume and assumed to have the same weight per volume. You have to be accurate when mixing the ratios, but, if you use say 10 oz hardener to 21 oz resin, the epoxy is going to cure without problem. Its not like uh oh, I used 10.2 oz resin to 5 oz hardener. Better throw that batch away! One simply does not have to be that accurate all of the time to use epoxy.

Re: The Way to Measure Epoxy Mix

Posted: Thu Mar 31, 2011 6:08 am
by jcallends
Early on I weighed my first quart of resin and hardener, resin was almost 10% heavier by volume for this epoxy. Instructions of course specified equal volumes for the mix. I weigh measured the first dozen mixes adjusting for the weight difference, the volume difference was obvious and never had a bad mix. With so many different kinds of resin and hardeners I would never make the assumption that I could ignore the weight difference. Considering the expected end results of an epoxy mix it should be done as carefullly and accurately as any other part of your boat. Follow the suppliers directions exactly without any assumptions.

Re: The Way to Measure Epoxy Mix

Posted: Thu Mar 31, 2011 7:23 am
by BayouBengal
With so many different kinds of resin and hardeners I would never make the assumption that I could ignore the weight difference. Considering the expected end results of an epoxy mix it should be done as carefullly and accurately as any other part of your boat. Follow the suppliers directions exactly without any assumptions.
Definitely.

I should have added that in System 3's epoxy book it also states, "Don’t make the mistake of using the volume ratio when measuring by weight . We formulate products to be used by simple volume ratios 2:1, for example) as much for packaging purposes as any other reason. Weight ratios are usually expressed in parts of hardener to 100 parts of resin. Volume ratios of 2:1 are often equivalent to weight ratios of 43/100 because the hardener is less dense than the resin. Check the Product Data Sheet to get the correct weight ratio if you measure by weight."

Re: The Way to Measure Epoxy Mix

Posted: Thu Mar 31, 2011 7:57 pm
by Cranky Badger
gstanfield wrote:"Why not just pull it into the syringe like you normally would"?
What if you're using a thixotropic resin ?
I've got one cold cure formulation I use that would have you sitting there all day trying to pull it into the syringe.

I use Epiglass resin and I just keep a damp mineral spirit-soaked piece of rag to wrap around the nozzle on the hardener when I'm done. The resin pump doesn't seem to plug up at all.