Diamond and CBN plates often consist of coated steel plates. Thus, they are usually exemplary flat, but a possible problem is then the use with water as a lubricant. The steel base plate can form small cracks and then becomes susceptible to rust. It is therefore recommended to add a rust inhibitor to the water. How to dispose of such a mixture is not quite clear to me. But if you just wet the plate with this mixture (so that it dries by itself), it should not be a problem.
There is an anti-corrosion concentrate from Tormek (ACC-150, for dilution with water). This does not appear to contain any oil. Tormek expressly permits watering artificial stones with it as well. So you can assume that this will not contaminate your water stones with oil. The use of oil is also recommended sometimes. This would have solved the Rust problem but you must then watch out for oil stains.
In most cases, you can use these “stones” without any lubricant at all. However, then there seems to be a small cloud of grinding dust. You have to bite the bullet.
If the base plate is made of plastic or aluminum, the problem does not arise.
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