How to Use Seam-It: Cure Issues
There are a couple of recommendations to keep in mind when using 10 to 1 dual component glues
for fabricating solid surface
One of the most common misconceptions regarding 10 to 1 glues is that all dispensers provide identical performance, Based on our experience and extensive testing, we know that there are marked differences in cure consistency. Specifically, the lower cost all metal dispensers tend to have a very high mechanical advantage. This high mechanical advantage can result in off ratio mixing of the two components if the user pulls too hard on the trigger.
To explain it another way, a high mechanical advantage in combination with operator strength will result in excessive pressure on the cartridge causing the cartridge to bulge slightly. When the cartridge returns to its original size after the trigger is released, the glue component (large side) will continue to flow out of the cartridge while the activator component (small side) will not. This problem results in an area of the bead where the 10 to 1 ratio is off and the glue bead will have "hot" and "cold" spots in the cure.
To test this theory for yourself, simply take a cartridge of glue (a lighter color will give you the best result), purge as always, and lay out a bead of 6 feet or so on wax using an excessive amount of pressure on the trigger. Every time you re-trigger, deviate from the bead a little as a mark for later. Continue to crank on the trigger and run out about a third of the cartridge. Make sure to pull hard on the trigger. This will mimic the high mechanical advantage of a lower cost gun if you are using a higher quality tool. If you are already testing with a metal dispenser, the results will be accentuated.
Observe carefully the differences in the curing material along the length of the bead. Notice how there will be sections of bead that cure significantly slower than other others. If you have used a light color, you may also see areas of discoloration due to "hot spots". These "hot spots" cure faster because there is the same ratio fluctuation. In extreme circumstances, the bead may not cure at all in small sections or the discoloration will ruin the appearance of the seam.
To solve cure issues, the answer lies in both the operator and dispenser. If you want to use an economy model for cost savings, be sure to apply even pressure on the trigger to minimize ratio fluctuation. The best option is to purchase a higher quality tool that is designed to limit the adhesive output and provide an even cure.
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