Epoxy is a fun but expensive product to work with, so you want to mix the right amount for your project. Mixing too much means you’ll have that expensive epoxy left over after your pour. But if you don’t mix enough, you’ll be short. Not having enough epoxy is especially bad if you’ve used mica powder, pigment, or other additives to give the epoxy a unique color or look. Mixing more, and hitting that exact same look, can be very difficult.
First we’ll calculate the volume of the area you’re filling. The formula for volume of any object is thickness x width x length. Let’s do a sample. If you’re doing a table top pour that’ll end up ⅛” (.125”) deep and the area you need to cover is 7” x 14” the math is .125 x 7 x 14, which equals 12.25 cubic inches. When you do the math, make sure all the numbers are using the same units (inches).
Change to ounces
Convert cubic inches to ounces by multiplying your result by .55. So, in our example, you need 6.8 ounces. Easy peasy.
A dose of reality: some epoxy will run over the edges of a tabletop pour. Some will stick to the side of the cups you mix in. Bottom line—you need to mix a little extra, no matter what. As a general rule, add about 10%. Your mileage may vary.
If you have way too much
Too much epoxy? You should always have silicone molds for something such as coasters on hand. Pour the excess into the molds and you’ll get a second project from your pour.
Epoxy is a fun and interesting medium to work with. We’ve got LOTS of great epoxy projects for you.
An easier way to calculate how much resin to use to fill a void is to fill the void with uncooked rice, agitate the void so the rice settles and level off the rice to the top of the void. Now pour this rice in your measuring container, add 10% for spillage and that’s the amount of resin needed. No calculations required!
Have something ready to use the extra epoxy on. Handle of a outdoor tool, coating the top of a bench, gluing the chisel into the handle etc. EEE
A much easier (and exact) way is to close off the open end with a scrap piece of board with double-sided tape then slightly over-fill the cavity with sand. Pour out the sand into a bucket, then into a measuring cup – giving a direct measure of the volume of epoxy needed.
For large irregular voids, fill the void with dry fine sand, vibrating the sand by vigorously tapping the board. Overfill and screed the surface flush with the top of the board. Dump the sand into a trash bag (with no holes) and then transfer the sand into a container with liquid measure marked with ounces or cups. convert the number of ounces or cups to volume using a calculator found on line. Finally, add 10%. A quart of epoxy resin costs about $50, a gallon about $100. Rough estimating for large pours could lead to a waste of a lot of money. Worse, under estimating will ruin the project and and the loss of the cost of the board, which is also very expensive. Better to over estimate.