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MAX CLR working time

Question:  Gerald, MAX CLR is taking 6 to 9 hrs for it to get hard enough to sand. Any way to speed things up? Room temp is maintained at about 78 to 85
degrees. It’s taking me way too long to finish my parts having to wait between coats to cure, sand, coat again. I have to wait a total of 18hrs for 3 coats.

Answer: The long set-time of the MAX CLR TC resin system is what gives the resin system its color stability, impact resistance, and durability. The faster a resin system cures, the faster it will turn yellow and often yield very brittle performance, thus yielding poor impact resistance.

Also the faster the reaction, the higher the shrinkage factor will be as the resin converts from a liquid resin to a solid plastic. High shrinkage of the coating will cause the substrate to warp and be dimensionally unstable. Six to nine hours is about right for sanding time of the MAX CLR TC; our recommendation is 12 hours at 75 deg
Fahrenheit.

Yes, warming the room will help with a shorter sanding time; to further accelerate the cure, you can also prewarm the resin and curing agent to 80 to 85 deg Fahrenheit before mixing. Pre-warming the resin and curing agent will shorten your pot life considerably so be careful not to overheat the components and observe the shortened working time. If you apply subsequent coats within 18 to 20 hours, you really do not need to sand the previous application as the MAX CLR TC will bond to itself.

Here is a typical multi-coat application:

I suggest doing some small experiments with temperature and time variations.

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