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See 'Half-tone'

Raster ruling L/cm or L/pi

The raster ruling is indicated in lines resp. dots per cm or inch. In screen printing, rasters between 5 L/cm till max. 48 L/cm can be printed, depending on the mesh used.
Guideline: the smallest dot must have a minimal diameter of two threads and one mesh opening.


1: Exact congruence between original (e.g. diapositive) and the printed image
2: Multi colour printing: exact congruence between originals of the various colors and their printed images (color register)
3: Exact congruence of images at the beginning and the end of a print run, or between intermediate printings.

Residual shrinkage

The amount of shrinkage remaining in a fabric after it has undergone all fabric weaving, washing and heat setting steps.


Substance retained in the upstream side of a filter.

RF (radio frequency) welding

Utilizes specific bands of radio frequency waves which are directed through specially constructed tooling to form localized melting/joining of certain dielectric thermoplastic materials. Can be used to form hermetic seals. Also known as high frequency or dielectric welding.


Sefar Inc.

111 Calumet Street
Buffalo, NY 14043 – USA

Phone 800 995 0531

Fax +1 716 685 9469

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Filtration & Separation

Screen Printing