July 11, 2011

Baiting

The large test strips were baited for the third time in the pepsin solution at 37 C. After several hours the fat had been removed from the pieces of hide and they were removed from the solution.

Soaking
The large test pieces were put in distilled water to remove the excess pepsin solution.

Debarking

Bark was removed from the oak branches using a draw knife to be used as a vegetable tannin. This bark was placed in distilled water to extract the tannins.

Alum Tanning
The piece of hide in the alum solution was left in solution to continue the tanning process.

June 10, 2011

Dehairing

The test strip was removed from the HaOH solution and laid flat on the table. NaOH solution was disposed of in a labeled hazardous waste container.

Hair was removed from the hide by running my fingers over the hair applying light pressure. Hair was discarded.

Soaking
The test piece was soaked in distilled water to remove the NaOH. The resulting solution had a pH of 7.5 and was discarded in the same hazardous waste container as the NaOH solution.

Baiting

1g of pepsin was added to 500 mL of H₂O and heated to 37°C. Pepsin is an enzyme that digests proteins. In leather tanning, pepsin is used to dissolve unwanted proteins from the animal hide leaving behind tannable collagen in the skin.


Debarking

 
Bark was removed from oak branches with a draw knife for vegetable tanning. 

The bark pieces were placed in distilled water to removed the quercitannic acid from them. Quercitannic acid is the tannin found in oak bark with the formula C₇₆H₅₂O_46. 

The solution immediately began to turn an amber color. The pH of this solution was 6.5.