We probably do not say enough times that the subjects that are addressed in this publication originate with those folks who use penetrants.
The last issue featured information about hydrophylic emulsifiers, and as usual, we received comments on the article. We relish receiving comments, because they come from the users of penetrants, who have vastly more hands on experience than we do, and those comments
always manage to sharpen what we have published.
In the case at hand, a couple of additions to our article were suggested. The first of these was that the generation of a refractometer concentration chart for each batch of emulsifier is not necessary. The objective of making the curve is really to calibrate the refractometer, and as long as the same instrument is used with the same manufacturer’s emulsifier, the chart should be adequate. Variations in the emulsifier from batch to batch are small enough to not be of consequence, and making a new curve for each batch would essentially
result in the same curve. Naturally, you must make sure that the curve that you make refers to a specific refractometer that is used with a specific emulsifier. Making a chart for one manufacturer’s emulsifier and then trying to use it for a different manufacturer’s emulsifier will not work. If you have emulsifiers from different manufacturers, you must assign a specific refractometer and its chart to each manufacturer. Where the calibrated refractometer comes into play is when you need to add new emulsifier and/or water to the tank to bring the level up.
When this is done, the tank likely has more than one batch of emulsifier in it, but as long as you use the refractometer that you have calibrated, no matter how many different batches of emulsifier are in the tank, you should be OK. If you use Met-L-Chek E-58D emulsifier, we supply a graph that uses a specific refractometer and can supply the same instrument for use with E-58D. If you use E-58D and already
have a different refractometer, when you make your chart, you will find that the curve shifts a bit to the right or left of the curve generated with the instrument that we use.