For monitoring the condition of acetate and nitrate film. Film archives throughout the world are fighting against time in a desperate attempt to preserve their collections. In the first half of the 20th century nitrate film became explosive and now colour fading and 'Vinegar Syndrome' are problems for acetate films. The Danchek 24-hour pH Indicator Strip is a piece of dyed filter paper, 10 x 40mm. It is a very sensitive indicator and will sense 'Vinegar Syndrome' when in contact with film.
The colour is blue when fresh in the pouch, changing to pale yellow when exposed to an acid environment. There is a small bag in the pouch filled with silica doped with a strong alkaline to preserve the colour until needed and it is important to squeeze all the air from the pouch each time the indicators are used.
Danchek pH Monitor Window fits into the side of a film can or box and monitors the atmosphere within for any signs of acetic acid.
The Danchek Acetate pH Monitor can sense degrading films long before vinegar is smelt. If the Danchek Monitor shows light green - pH4.6 the film has probably reached the autocatalytic point and duplication of the film should be considered. The monitors are light-sensitive and should be treated with care. Keep them in a bag in the dark until needed.
METHOD: Place the Danchek pH monitor filter paper on the film (with gloves) and start the stopwatch. The strip test takes two hours and is a very accurate way of testing a film. Tests are performed at room temperature. If the colour changes to olive green you have reached the critical autocatalytic point, which is the point when you should consider separating the film from the rest of the collection and schedule the film's duplication. If the indicator strip has not reacted within 24 hours there is nothing critically wrong and the film may be stored in the vault. Do not leave the indicator in the open air because it will fade within 24 hours.
The Danchek Acetate Film pH Monitor Window clips into an 11mm hole for which a special film can punch can be supplied.
Danchek Film Can pH Monitors could also be used in Boxes and Storage Drawers by drilling an 11mm hole.