Screen printing

Letter press---this most ancient method of printing. In this method letters are arranged one by one on a plate and printing is done from a raised plate form. Ink is applied on raised surface and paper is pressed. It is costly, time consuming, having less scope for creativity.

Off set printing----- it is printing from a flat surface. Material is transferred electronically to a printing plate. Ink is applied to plate, and then blanket wash on the press washes the plate clean except where the impression is located. The image is then transferred to paper.

Screen printing---it was invented by GUY MEOY (new yark) in 1936. Screens made up of metal silk, fabric are used for printing. In this stencil is made and placed on tact screen. Ink is passed over stencil –impression goes on to paper stock except where stencil prevents flow of ink. It can be done on any surface.

Material---------1 printing table       2 glass sheet    3 screen frames       4 c or g clamps      5 drying racks

          6 nylon bolting cloth                        7 hammer, nails    8 screen coating      9 ammonium dichromate    

10  5 star film        11 hydrogen peroxide       12 faster capillary film     13 chromo line film    14 bleach

15 printing frame      16 exposing table     17 squeegees     18 ink knife    19 paper, gum, PVC sheet, colors

Frames ------may be of wood, metal, but all adjacent sides are right angles .8*10, 10*12, 15*22,    jolts may be dovetail, half lap, mortise, and picture frame type.

Bolting cloth --- cloth are organdy, nylon, wire cloth of stainless steel, cooper. Named as per 8 to mesh count. The no multiplied by 10 will give details of holes in 1 inch sq. 40 no means 400 holes in 1 inch. high mesh count give fine details .less consumption of ink .but lower count is good 4 stickers ,labels ,posters , 50 no is good 4 letter pads , visiting cards .

Raxin tape --- ½ or 1 inch width

Nails -----13 mm

Squeegees   --- 4 inch wider than design with high hardness.

Printing base ---- flat with g clamp attached.

Modes of typesetting --------dtp setting ……graphic setting(photographic positive print out of yr matter)  art work—logos, designs , made on O H paper by artist .0.5 point pens ,Indian ink used 4 it . -----------------

Dry transparent sheets--- these r stencils of words used when dtp not available, borders, flowers, designs r on it.

Material required for exposing---- lath positive of printing matter or dtp print, art work, dry dip sheet 2 coating solution –polyvinyl alcohol emulsion 3 sensitizer-potassium or ammonium dichromate is used

4 film 5 black paper 6 hydrogen peroxide –used as developer 7 water, tray, scissor, 8 glass sheet 4 mm thick

Exposing—it is 3 types---- 5 star method ----it is simple, indirect method, film is red in color and very sensitive to light. It has half tone effect; means in one film u can have many shades. Photos can b printed with this, very good for printing. method—add 1;3 hydrogen peroxide and water – cut film larger than positive—put pos active  in read able position --- put glossy side(emulsion)on it.---put it contact box ,expose 4  100 sec , in arc lamp 1 ½ min – wash film in hydrogen peroxide and water 4 75 sec –wash in hot water---stick it on mesh – remove plastic sheet from it  -apply coating on both sides of film , fill up holes – stencil is ready for printing

Inks used 4 printing ----oil based ink         glass matt ink         PVC ink      foil ink       politic ink     ceramic ink        p c b ink         metal ink       textile ink     

Material used in printing ---- printing base       g clamp      pace tape     inks     reducer     thinner  

Kerosene      squeeze       cotton waste      drying racks

Direct method--- it is used for big banners   it has short life , it is green in color ,mix 100 ml silkote63, 1ammonium dichromate , 3 drops of water or add ammonium dichromate and coating solution 1;10 ratio

2 Coating solution 100 ml silkote sanitizing solution  10 ml ammonium bichrote add both 10;1 add water stir well . Apply to screen, dry in dark room, expose it develop it, stencil will b green ----di

rect coating is also available

chromatin film method-0----  film is blue in color  1  add coating solution and sensitizer 10;1 ratio   ---put emulsion side up ,put it on screen – apply coating on back side film is fixed --- dry it , remove plastic – keep negative  in readable position  ,pries with glass ,expose 45 sec –wash it – put paper film , stencil is ready 4 exposure

Types of printing

 ceramic printing 850 –900 c  ---------glass color   500 ---550  c    hand painting , screen painting, transfer print , cutting print sand blasting , acid etching