Sorry, just a knee jerk defensive reaction. Are you working with scales in your professional life at this time? Calibrating is a novel idea. The scales we have used have all been "Best Buy" kitchen appliances with a 1 gram resolution (supposedly). There are noe calibration features on these, at least the manuals dont say anything about it and there are no extra buttons/dials/screws to work on. Perhaps putting a known weight like a piece of steel on the scales before measuring epoxy is better than just mixing epoxy and looking at the results?

If we find a model able to measure in grams, which the two new models we have tested so far have not done, we will buy two. By doing so we are reasonably certain that the scales used will last indefinately..

Kevin, what you say about the mixing ratios are interesting. You finish it off by saying that homebuilders will not get super accurate results anyway? Taking it one step further, will the pre-pregs have better quality on the mixing ratios of the matrix? Is that another of the variables which can make a pre-preg product "better"?