Methods of dissolving HPMC in cold water

when dissolving the HPMC (Hydroxypropyl Methyl Cellulose) in cold water, you may face this situation: HPMC is “insoluble” in water and form white flocculates. keep stirring, it won’t work.
But actually we all know that HPMC (Hydroxypropyl Methyl Cellulose) can soluble in water, so why ?
The reality is HPMC doee not dissolving in water at the first time, and gel will be formed on the surface of hpmc and prevent the inside part dissolution. So that’s why we find HPMC “insoluble” and form white flocculates.
how could we dissolve hpmc without surface treatment in cold water?
There are TWO ways for “Non Surface Treated” HPMC’s dissolution:
Hot water dissolution: Since HPMC is not dissolved in hot water, so in initial period the HPMC can be evenly dispersed in hot water, and followed by rapid dissolution while cooling.
Powder mixing method: Fully mixed the HPMC powder with lots of other powdery material ingredients by using mixer, then add water to dissolve the mixture. In this case HPMC would dissolve without forming flocculates. That is because HPMC Powder has already homodispersed and will immediately dissolve when meet with water. - Putty powder and mortar manufacturers are using this method.