Select proper screen printing meshes for different applications

April 26, 2011 - PRLog -- During the last ten years there have been fundamental product changes in commercial screenprinting; these de-velopments were slow to filter through to printmakers. The introduction of water-based inks has brought a reappraisal of working methods. This article discusses one such change, (in mesh technology); others will follow.
With the newer water-based inks, mesh has a greater role to play. As the solvent for the inks is water, a minimum deposit is required to prevent undue expansion of the paper; opposed to this, most water-based inks use pigment in suspension, thus the aim is for a heavy deposit to increase colour inten-sity. Mesh count therefore becomes more specific to the brand of ink; and, to my knowledge, there are now 19 different inks available. The pigment in some of the cheaper brands is not as finely ground as that in some of the more expensive brands, so will not go through the finest meshes easily. However, some general rules apply.
Traditionally, there are two mesh thread diameter descriptions: t and hd (t = standard, hd= heavy duty), which are interpreted differently by each manufacturer. More recently thread diameter measured in microns is being introduced as a standard description. So meshes are now denoted in two ways: one a figure (number of threads per centimetre) and a letter (diameter of thread), one a pair of figures (threads per cm and diameter in microns).
The accepted norm for all

1. Solvent- based screenprinting inks in mesh counts was 90t for general printing and 110-120t for fine detail.

2. With water- based inks use 120t (120.34) meshes for most printing, up to 150t (150.34) for fine halftones and,
3. A solid back-ground that needs strong colour, 90t (90.40 or, for some manufacturers, 90.48) but be prepared for some cock-ling or paper expansion.

It is now more important to have screens stretched tightly and evenly, 14 newtons is average for 120t screen (a newton is the Si unit of force used to measure tension).

Monofilament polyester meshes, which have replaced all other types for most uses, come in several forms. Plain weave is fine for all printmaking uses. The newest high modulus meshes stretched to very high tensions are too new yet for general use;

twill and calendered meshes are probably not applicable for most printmaking. The recommended meshes combined with a very sharp squeegee and the correct amount of snap whilst printing, reduce surface tension to a minimum, allowing a controlled quantity of ink and therefore water onto the paper.

If you use direct emulsions, it also costs far less to coat a screen with tight mesh, as you can obtain a much thinner deposit. Orange dyed meshes (Anti halation) stop the light from being reflected and scattered when using direct coatings and this is important for fine detail and halftones.

It is usually cheaper to have screens stretched professionally than it is to buy the mesh and do it yourself. Alu-minium screens are recommended as they are cheap and do not warp, thus keeping the mesh tight. Or if working to a tight budget it is possible to buy pre-stretched wooden or MDF frames.

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Share Filtration is a Chinese manufacturer and supplier of woven filter fabrics, woven screen and filter meshes and various kinds of printing meshes. We are able to accept custom orders up to specifications provided.