To produce the track layout on a copper-clad board so that an electronic circuit can be made by etching away unwanted copper. 

A document which covers general and specific hazards and risks in darkroom work, guidance on how these can be managed and such safeguarding issues as might apply.

Developing colour or black and white films or prints. Fixing colour or black and white films or prints. Stop baths used between developing and fixing. Chemicals used for specialist treatments.

This gives some examples of methods of waste disposal from D&T facilities.