Ultrasonic Cleaner

[Kenny Durrant]

I'm in the process of changing over to a HF cleaner and I noticed something strange. The first time I used it all went well except the resin set too quickly. The second time I used hot tap water and not the heat from the cleaner and had the same results. The third and last time I used a thermometer and heated the water to 80 deg. Then I add the resin and let the temp of the resin match the water. When I started the cleaner the resin climbed to 100 deg. very quickly so I turned the cleaner off. When I checked the water temp. it was still at 80 deg. All this was with raw resin, no mepk was added at this time. The thermometer is a cheep one, not a mercury them., but when it went back and forth from the water to the resin the temp. was consistent. If the reading on the thermometer is off there is still a big difference between the water and resin temps. I guess the next step would be to monitor the resin and not worry about the water temp. Does this sound impossible or what's your thoughts. Thanks Kenny

 

[PenMan1]

Heating resin does, in fact, make the curing process speed up dramatically. Unfortunately, the "speed up" curve is not linear.

Depending on the temperature and humidity of your location, it is likely that you will have to adjust your catalyst amounts for thinned resins.

This time of year, in South Georgia, in a 70 degree workshop, Silmar 41 with 4 drops of MEKP that has been heated for 2 480 second heated cycles will begin curing in about 90 seconds.

Unfortunately, this will vary by location, but in many places I've worked, turning on the HF heated ultra sonic cleaner for 5 minutes and the 2 480 heated cycles will produce resin that will begin curing in less than 2 minutes.

My experience has been that going LESS THAN 2 cycles GREATLY REDUCES the effectiveness in bubble reducing.

I find that 2 minutes is the perfect working time for me, BUT it does require a good deal of "prepplanning". For example, with a 3 color pour, I have all my catalyst pre measured and while I'm pouring the first color with one hand, I am stirring the MEKP into the second color, etc.

I ACTUALLY LIKE the quicker cure times as it reduces a good deal of "down time" in the casting process. Every caster has different methods and techniques, and JUST as you get everything working perfectly for your location and application, the temperature or humidity changes and everything has to be adjusted.

My other advice is to put the thermometer on your porch as it is virtually worthless in the casting setup. If changes in resin temps produced regular or linear changes in the resin, it could be useful. After 35 years in the fiberglass boat business, I can prove BEYOND reasonable doubt that these environmental changes ARE NEVER LINEAR.

 

[Janster]

....HF Ultrasonic.....2 minutes of stirring the Sinlar in a cup in hot water, just hot enough to not cause pain if you test w/your finger add 4 drops of hardener for 1.5 ozs and stir two more minutes and pour! Has worked fine so far. YMMV

 

[Kenny Durrant]

Thanks for your comments. I noticed the temp. change while degassing the resin. There wasn't any mepk added at this time. I was hoping that if I could get a closer handle on the temp. of the resin maybe the humidity wouldn't play such a big part. Like you said I'll just keep playing with it until I figure it out. Thanks again.