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Gear Test: Small Batch Epoxy Scale

I have been using WEST SYSTEM epoxy products for almost as long as I have been involved in boating, and I have found them easy to use, with reliable and predictable results. As with most products, there are a few small issues that could be addressed to make things a bit more convenient to use, but I’ve learned to live with them, mainly due to the overall effectiveness of the product line.


When attempting to mix small quantities of resin and hardener, users have been limited to some degree by the need to use full strokes of each pump to be certain of achieving the correct ratio, which often results in mixing a larger quantity than required. In addition, the pumps occasionally will include a large air bubble when dispensing the product, especially following an extended storage period, and leaving the pumps attached to the gallon-size resin container creates space issues for storage. WEST SYSTEM has all but eliminated these and other issues with its new 320 Small Batch Epoxy Scale, which simplifies measuring both resin and hardener for small projects, with a scale capacity of more than 4 fluid ounces.

I’ll have to admit to using my own much larger gram scale when a project requires large volumes of epoxy, but it isn’t convenient to bring it out every time I need to mix a small batch. The Small Batch Epoxy Scale comes as a kit containing the electronic scale, two sealable dispensing bottles, mixing sticks, chenille pipe cleaners, and both 1- and 3-1/4-ounce plastic mixing cups —everything necessary to mix small quantities of epoxy.

The scale is enclosed within a sturdy, hinged plastic case measuring 5 inches long by 3 inches wide by 3/4 inch thick, and fits in a shirt pocket. The clearly written instructions are adhered to the case lid and explain the procedure for calculating the 5-to-1 ratio for using either the 205 or 206 hardener, and the 3.5-to-1 ratio for use with 207 or 209 hardener. There also are scale calibration instructions included with the packaging. The scale operates on two included AAA batteries.

I didn’t need to look far for a project requiring small batches of epoxy, as Soundings editor Bill Sisson reminded me that a few rail base screws on his vintage Boston Whaler Nauset had been working loose during the season and required attention. The directions on the scale read as follows:

When using 205 or 206 hardener with 105 resin:

1. Pour hardener into the cup to about 1/6 the total amount of epoxy that you wish to mix.

2. Record the weight of the hardener and then multiply by 6.

3. Pour 105 resin into the cup until you’ve reached the newly calculated weight.

This procedure allows easy and precise mixing of the smallest amounts of epoxy. As an example, using my group size “A” pumps, I dispensed 4.1 grams of hardener (one stroke), multiplied by 6 to get 24.6 grams of total weight required, and added the resin until the scale totaled 24.6 grams — a 5-to-1 ratio. That volume of mixed epoxy was more than enough to fill a WEST SYSTEM syringe. Where the scale really comes in handy is when you need to mix smaller amounts of epoxy than the single pump stroke will allow. Using the included dispensing bottles, just tip in the volume required. The scale also is a great way to check the accuracy of your pumps.

Using the scale to mix several batches of WEST SYSTEM epoxy highlighted a few points:

• It doesn’t require much of an air bubble in one of the pumps to alter the mixing ratio substantially. The scale eliminates this issue.

• It is much easier to control small quantities of resin and hardener if you use the included dispensing bottles as opposed to conventional pumps.

• The scale will shut off after 60 seconds, which can be frustrating if it occurs in the middle of pouring. But as long as you remember the total required weight, you can get back on track after turning the scale on again.

• I recommend draping a piece of clear plastic kitchen wrap over the scale while working with the epoxy to keep any spills from working their way into it.

• Make a copy of the instructions that are on the inside cover, as they are bound to get damaged over time.

• Using the new scale has prompted me to dust off my larger scale for use with WEST SYSTEM products.

The 320 Small Batch Epoxy Scale is an inexpensive offering that enhances the flexibility of WEST SYSTEM products. With a retail price of $37.95, I feel the kit should be a required addition to everyone’s WEST SYSTEM tool box. Visit for more information, or contact the company in Bay City, Mich., at (989) 684-7286.