Views: 414 Author: Site Editor Publish Time: 2012-05-02 Origin: Site
We get variable results on exactly the same formula and mill, especially if we aren't running them frequently. Same pigment, same resin, even the same manufacturer and lot number. And sensible reason?
This can be a tough one, but you can localize your search to the materials themselves.
USUALLY it is a pigment matter, and even more specifically, a pigment like a blue which is used in small quantities, and which by nature is made of almost colloidal-size particles and is highly hygroscopic.
If you open a bag in March, and finish it off on a batch in May, you have gone through some violent changes in humidity, certainly enough to cause havoc in the condition of the pigment. Other pigments, as the pigment people will tell you, are extremely hard to hold to exact similarity unless they are kept under good moisture conditions. Look under the last bag or skid of pigment the next time you use up a pile, and you will probably see a moist spot in the concrete! If you have such a pigment, buy as sparingly as possible, and store carefully, favoring these materials in location in storage.