After swelling, dissolve it completely in a boiling water bath and leave it cool to room temperature. Measure

the viscosity of each solution at 20±0.1°C by Brookfield Viscometer with UL Adapter.Then, measure accurately

the concentration of each solution (Note 1). Report the viscosity (Cps) of 4.00 wt% solution as estimated from

a curve based on the relationship between concentration and viscosity, as follows:

PVA solution of above-mentioned grades can be applied to the mold by brushing or spraying. The viscosity of

the selected grade and concentration determine the thickness of release coating. About 10 to 30 wt % of solid

content is recommended for this purpose. Up to 15% of plasticizer, such as glycerol or ethylene glycol, relatively

to the weight of PVA, can be added to the formulation to improve the flexibility of mold release film.

Polyvinyl alcohol exhibits low acute toxicity to aquatic species.

Fish (Pimephales promelas) 96-hr. LC50: > 40,000 ppm. Fish (Lepomis macrochirus) 96-hr. LC50: >10,000

ppm. Crustacean (Ceriodaphnia dubia) 48-hr. LC50 = 7,850 ppm. Crustacean (Daphnia magna) 48-hr. LC50

= 8,300 ppm. Bacteria (Photobacterium phosphoreum), Microtox Method, EC50: >50,000 ppm.