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I used an OHAUS triple beam balance to do my testing. It's accurate to a tenth
of a gram. I have it set up to always balance with the weight of an empty cup on
the platform. I also test a cup on the balance prior to filling it to make sure
it still zeros out.
 
I noticed that if I took the output from the pump and measured each component in
a separate cup, there would usually be a significant variance to what was
expected on some throws. I could never figure out what factor was causing the
inconsistency. Some throws would be very accurate, and others less so. I had a
sheet of readings, but threw that out long ago.
 
I spent an afternoon in an air conditioned garage (Texas summer) testing various
patterns of use and always found that out of a number of samples some would be
off. Every once in a while, it would be way off. I tried from 1 to 8 pumps per
test. I got used to looking at how much chemical came out and sometimes I could
visually tell I was going to have a bad charge.  
 
I called the manufacturer and got some replacement valves and seals to try to
"repair" the unit. I thoroughly dismantled and cleaned the pump with MC and put
the new parts in along with factory fresh chemicals. Actually, I had an
experienced IV-P builder help me with the cleaning and reassembly so that 2
brains were looking at the problem. That didn't change a thing. I returned the
whole unit to the factory, and got another one.
 
I then ran the same tests. The new unit was better, but still not completely
reliable. One thing I did notice was that if I operated the handle very slowly
on the down stroke, I got better results. I always let the spring take care of
the up stroke except I would make sure it went up all the way. Sometimes I
noticed that the up stroke didn't go completely up just with spring action so I
always helped it along that last quarter inch if necessary. No matter how I
treated the pump, it would throw a bad charge sooner or later.
 
I wasted my time and over half a gallon of resin and an associated amount of
hardener and finally decided I had enough of this time and chemical saver. What
started me on this quest was a particular BID application that never completely
hardened. I had to grind it out and re do it, and the second application also
didn't set up the way I expected it to. I could put a knife blade into the BID
and it would slowly deform. I always kept the garage at 75 degrees during any
epoxy work including the 24 hours to partially cure it.  
 
Once it finally dawned on me that I had a problem, it became clear to me why
some of my early work produced BID that was more red in color. The pump threw
more hardener. Other times it threw more resin and the result was a deeper
green.  
 
I posted the formula and steps I use to measure by weight several months ago.


Bill Gradwohl
IV-P Builder