1. Make up a washing powder, adding 1-2 g of protease for every 100 g of enzyme-free
    powder.

2. Use a 1% solution of the mixture.

3. Add strips of photographic film about 4 mm wide to the washing powder solution.

4. Incubate in a water bath at 50-60^oC for 10-20 minutes, or until the film has cleared.
    Gentle agitation may be needed.

5. Record the time taken to completely clear the photographic film.

6. Remember to carry out suitable controls using enzyme-free washing powder solution alone.
 
 
 
 

Safety

The enzymes used here are identical to those found in washing powders. They are
encapsulated in a low melting-point wax and are therefore safe to handle and unlikely to
form airborne dust. Unnecessary contact with the dissolved enzyme should be avoided.
Wash splashes with plenty of water. Spills of enzyme solution should be wiped up promptly.