LR White Technical Tips - Distinguishing LR White from Tissue
If you are having difficulty locating your tissue in LR White after it polymerizes due to the fact that the color of your tissue is the same as LR White once polymerized, there is a solution. Dye the LR White using any oil soluble dye. Remember, however, that the intensity of the dye needs to be very high if contrast is to be seen at high magnification. Dyes with phenol or tertiary amine groups should be avoided because they effect the rate of cure of the resin. It is our experience that Sudan Black (cat. # 21610) is the best dye to use due to its color intensity. To make up a stock solution, add the dry stain to the resin until a saturated solution is obtained. Then proceed as usual.
If you require the pH of LR White to be neutral (the standard is 5) you can adjust it by adding small amounts of caustic soda or a primary amine. The best primary amine to use is Ethanolamine (absolute) for it will mix into the resin very easily. Small amounts are to be titrated into the resin and the pH should be constantly checked until 7 is reached. Do not add more than 50ml.