Applying the Sample

PRE TEST CHECKS

Check that the platen is clean and free from grease.
Check that air dryer indicator crystals are orange.
If green, change crystals; unscrew transparent container, empty refill with activated alumina and gel indicating crystals. Spare air drying and crystal mix is supplied with the instruments. Additional spares are available from Rhopoint.

Apply emulsion using 75 micron cube applicator from warm end right to cold end left, or in U-Shaped form starting and finishing right hand side.

RECOMMENDED

Apply a control strip using emulsion of known MFFT is recommended .
All coatings should be applied within ten minutes. If there is a delay in applying a track, close the cover to prevent ice formation, reopening the cover as soon as the next coating material is ready.
The use of several applicators is recommended if more than one emulsion is to be applied. Pre-fill hypodermic type dispensers with emulsion to further reduce preparation time.
Close the Perspex cover.
Periodically check the films, film formation time depends on temperature but all films should be formed in approximately 1 hour.
When films have formed (see illustration) set the temperature cursor to read point on track where the film has coalesced over 90% of the track width.

PIGMENTED EMULSIONS

The MFFT bar is sometimes used for tests on pigmented emulsion, where the MFFT determination is more difficult because there is no clearly defined change in "colour" of the coalesced film.
There is, however, a slight change in the shininess of the surface and using a wooden spatula, lightly scraped on the surface, it is easy to define where the coalesced film stops and where the remaining film is poorly integrated and heavily cracked with very poor adhesion.