Heating knives to red hot can distemper the metal; use cheap knives with non-conducting handles; single razor blades are good but can cause nasty cuts and they deteriorate quickly from rusting, etc.; best yet is a long thin blade with sheet metal handle, a Japanese industrial knife "Nikken Sofutu Kamisori" available from supply firms; sterilize them by baking. OD68-148
To kill Tobacco Mosaic Virus heat metal to boiling 212 deg.F. (100 deg.C) for at least one minute; to inactivate TMV in undiluted plant juice requires one minute heating at 96 deg.C. (204.8 deg.F.); for Cymbidium Orchid Mosaic Virus heat for 10 minutes at 65 deg.C. (117 deg.F.) C72-42