Mold can form on almost any surface where moisture and heat combine to facilitate fungus growth, including videotape. If you discover mould on your VHS tapes, or simply suspect mould due to the telltale smell, do not play them on a VCR or camcorder, which could gum up and malfunction as the tape heads rapidly become clogged with mould. Instead, eliminate the mould and possibly salvage the memories on your video tapes.
Press and hold the button on the right edge of the VHS cassette, as you are looking down on the top of the cassette. This unlocks the rectangular gate door along the front edge of the cassette.
Lift and hold the gate door, which swings up toward the top of the cassette.
Slide a thin microfiber cloth between the plastic cassette housing and the exposed videotape. Bend the cloth over both sides of the magnetic tape and grip the tape gently with the cloth.
Pull the tape out six inches from the cassette, working slowly to avoid tearing or stretching. Pulling out more than six inches at a time can cause tangling.
Pull the microfiber cloth along the length of the exposed videotape, removing the mould spores.
Turn the cassette upside down and insert an index finger in the left take-up sprocket. Turn the sprocket clockwise to advance the cleaned section of tape onto the take-up reel inside the cassette.
Turn the cassette over and gently pull more of the wound tape out of the cassette to clean with the microfiber cloth, and then advance the tape onto the take-up reel using your index finger to turn the reel. Repeat until the entire tape is cleaned or you no longer see evidence of mould, which may not have penetrated all the way to the spool core.
Blow controlled bursts of compressed air into the holes and crevices on the VHS cassette to dislodge mould.
Insert the tape in a VCR and rewind to the beginning.
Cleaning the tape with a cloth is a time consuming process, but it's the safest way to remove mould without dismantling the cassette, which may damage the tape and render it unplayable. Make a copy of the tape as soon as possible.