Several commercial designs exist using the special surface character of a soft polyurethane material [technically said to have "Shore A" character] originally designed by Eastman Kodak. The roller surfaces made from this material are "tacky" and remove dust and other particles onto their surface. The degree of "tackiness" is determined by the choice, softness and surface texture of the roller's coating. The rolling contact with the film and the cushioned surface of the roller provide a low risk of film damage by scratching.
The principle was patented by Eastman Kodak as Kodak PTR Particle Transfer Rollers but now made by a range of manufacturers.
When the PTR is fully loaded with dirt, after a few thousand feet, they can be washed with water or wiped with a damp sponge to remove the accumulated dirt [or a material with a surface stickier than PTR, such as adhesive tape can be used.]
These rollers are now extensively used in the film path of projectors, printers and telecines to clean prints during projection or transfer, which results in cleaner copies and cuts down on the build up of dirt in the mechanisms of the equipment. They can be fitted to any negative handling equipment or used as a "stand alone" film cleaner wound by hand or powered. They seem to work as well at any speed for example on high-speed panel printers at 600 ft per min.
In order to operate effectively there must be intimate contact between the film and roller but the angle of wrap is unimportant and can range from only a few degrees to over 180 degrees. The tension is not critical but should be sufficient to ensure that good contact is maintained. These cleaners do reduce the amount of dirt but they will not eliminate the need for liquid cleaning.
A number of units are on the market that consist of a powered rewind transport that passes the film through a number of PTR rollers. These units are useful to conventional laboratories and for cleaning modern restorations of archive images but are not effective enough for cleaning old archive film.
These are the trade name of rollers, which are intended for fitting to projectors or video machines as well as printers and rewind equipment in much the same way as PTRs above. They too, collect dust and dirt prior to printing, projection or any other operation.
The Drypur compound, a soft, putty-like substance, makes up the surface of the roller and attracts dust and dirt particles. It can be used repeatedly, but today are less used since the introduction of Particle Transfer Rollers, which are more effective and last much longer.