Re: Cup-in-a-cup?

Posted by Ken Leffert on Sep 30, 2007

I've had good luck mixing fairly small batches (15 ml. is my most common batch size) with a method known as cup-in-a-cup. I don't believe I've ever had any fail to cure properly. The weight idea should work, but I don't have any equipment accurate enough to measure that way.

Its a pretty simple process..... you make a gauge cup into which fits other mixing cups. The mixing cups are used once and disposed of, the gauge cup never gets anything put into it except a fresh mixing cup.

To set it up, you need a package of fairly transparent cups, the 3 oz. plastic bathroom cups from CVS pharmacy work perfectly. You also need an accurate measuring device, like a medicine dispensing cup, that measures liquid in 5 ml., 10 ml., etc. This measuring device is only used at first, to setup your cup-in-a-cup system. Finally, you need something to mark your gauge cup with, a new sharp-tip felt pen works ok.

To start, take 2 cups, one stacked inside the other, and place them on a level surface. Carefully measure 5 ml. of water into your medicine measuring cup, pour it into the upper cup of the 2-cup stack (obviously). Now, looking down into the cups and through the transparent plastic, mark the water level on the lower gauge cup with your marker and note that mark as 5. Pour out the water and measure 10 ml. in the medicine measuring cup, put that into your 2-cup stack, and mark the 10 mark on your gauge cup, looking down into the cups and thru the plastic like on the earlier mark. Pour out the water and start over to make a 15 ml. mark, a 20, a 30 and a 45 ml. mark on the gauge cup as well. Its important for accuracy to empty the 2-cup stack and start over for each measurement, its also important to label what each mark is on the gauge cup. You can make more marks if you want, but that's about all I've ever found useful. Now, to use this rig......

Discard the upper cup that you used to make your gauge, and stack a fresh cup into the gauge cup. If you want a 15 ml. batch, which really aint very much, add resin into the 2-cup stack, looking down into the cup and thru the plastic just like you did when you made the gauge, until it gets to the "10" mark, then do the same thing with hardener until it gets to "15" (that's 10 ml. of resin and 5 ml. hardener). With batches that small, you're not really pouring, its more like drizzling. Take the cup that actually contains the resin and hardener out of the gauge cup, set the gauge cup aside for repeated future use, mix and enjoy. You can do the same thing for larger batches, like resin to "30" and hardener to "45" for a 45 ml. batch. Just remember to never add resin or hardener directly to your gauge cup, add them only to a fresh cup placed inside your gauge cup, and your gauge will last forever, unless you crush it moving halfway across the country, like me 8-(.

WHEW!!! Sorry about such a long rambling for such a simple process, but its really pretty handy once you figure it out. And I'm intentionally leaving out about a million things, like first put on your rubber gloves, or I could just go on and on and on......

In Response to: Epoxy Mixing by Rocko on Sep 30, 2007