You may think, and probably correctly so, that further deterioration of the item can be avoided by removal of the plastic tape. The best advice in dealing with the repair of items mended with plastic tape is to seek the aid and services of a professional conservationist. Cardboard is another item to be kept well away from our philatelic materials. It is generally highly acidic, and the chemicals in cardboard are rapidly transferred and hasten destruction. If you require a rigid support of a philatelic item, use an all-rag type of board.
Conservators use chemical baths to eliminate mildew growth and stains.
Frequently, when papers have been cleaned and bleached, they are dipped in a gelatin bath in order to restore the paper. The glutinous sizing of the paper adds strength to it, and sometimes a corrective dye will be added to the gelatin bath in order to give the paper a tint close to its original color. Foxing, which is a stain caused by fungal growth, can often be removed by using a potassium permanganate solution of five drops per pint of water. Carbon tetrachloride or benzine are effective in removing grease and oily stains. These chemicals are very hazardous and must be used according to instructions on the containers.