One last thing that I forgot to mention: those resins are generally clear to amber in color. Fillers can be gray to white, depending on the material. Catalysts tend to be fairly clear. The manufacturers usually add a pigment to the catalyst. This is to help the user know that the catalyst is evenly mixed throughout the putty. If you have streaks, keep stirring! The pigment has no effect on the performance. One manufacturer's "red" filler can't be compared one-for-one with another manufacturer's because it is nothing more than their choice of pigments. I'm not aware of any industry standardization of color/application.
Bill
