Common sense about bandages(2)

Typical products
Viscose gypsum bandage is a bandage made of powdered calcined plaster, polyvinyl alcohol, and polyvinyl acetate emulsion to make a certain concentration of homogenate, uniformly spread on gauze, dry, and cut. It is suitable for orthopedic fracture fixation, deformity correction, inflammatory limb braking, bone tuberculosis, bone tumor and bone arthroplasty, limb fixation and mold model making. This product has controllable curing time, strong hardness, fast drying time, and strong adaptability , High temperature resistance, high cold, non-toxic, non-irritating, non-allergic. Properties: This product is gauze coated with gypsum powder, odorless.
Inspection: Take 3 pieces of the product per unit area and weigh them separately. Calculated by area, the weight per 1m2 shall not be less than 340g.
Category: For orthopedic correction of deformities, fixation of broken limbs and joints, etc.
Specification: 10cm×450cm
Storage: sealed and preserved.
Validity period: 2 years tentatively
Hardening time: Take 3 pieces of this product with a width of 5cm and a weight of 20g (approximately 1m in length), roll it loosely into a cylinder, immerse it in 30°C water, place it for 15 seconds, take it out immediately, and gently within 10 seconds Squeeze from the edge to the center until there is no water flowing down continuously, immediately wrap the bandage on a non-absorbent optical round shaft with a diameter of about 12mm, and start timing at the same time, take out the mandrel after 2 minutes, and use your fingers within 10±5 minutes Pinch, no collapse should occur.
Take this product from calcium sulfate, carefully shake off the calcined gypsum attached to the gauze, mix well, take about 0.15g, accurately weigh it, and place it in a vial. Add 15ml of water and 5ml of dilute hydrochloric acid. Heat to dissolve it and let it cool to room temperature. , Add 1 drop of 0.025% methyl red ethanol solution, drop the ammonia test solution until the solution is slightly yellow. Take another 10ml of water, add 10ml of ammonia-ammonium chloride buffer (pH10.0), 1 drop of dilute magnesium sulfate test solution and a little chrome black T indicator, dropwise add ethylenediaminetetraacetate disodium titrant (0.05mol/L) ) Until the solution turns pure blue, put the solution into the above-mentioned conical flask, and titrate with disodium ethylenediaminetetraacetate titrant (0.05mol/L) until the solution turns from purple to pure blue. Each 1ml of ethylenediaminetetraacetate disodium titrant (0.05mol/L) is equivalent to 7.258mg of CaSO4·1/2H2O, and the calcium sulfate (CaSO4·1/2H2O) shall not be less than 90.0%.