This week in textiles we did screen prints, Screen printing is a modern industrial development that has derived from stenciling. Screens are constructed of either a wooden or metal frame, with a mesh stretched tightly over the frame. The print technician prepares and also exposes screens. A positive image is needed to transfer onto the screen. This need to be either a drawn/photocopied black and white image onto tracing paper, or an image painted in opaque medium onto kodatrace. The final image needs to be given to the print technician.
The Process
Firstly, the screen mesh is coated in a light sensitive emulsion and allowed to dry in a dark space, usually a drying cupboard. Once dry, the screen is then transferred quickly to an ultra violet light exposure unit., the positive image is placed under the screen, and the screen is exposed to the light for the relevant time. The black/opaque areas of the image stops the UV light getting through to the light sensitive emulsion, this keeps the emulsion soft. The UV light is able to go through the white areas of the image, making the emulsion hard. Once exposure has stopped, the screen is then washed with a hose pipe and the pressure washer peels away the soft emulsion, revealing the screen mesh underneath. The exposure process is now complete.
Puff binder (Minerfoam B) is a paste that gives a 3D effect to fabric. it can either be screen printed onto fabric or hand-painted on. once it has been applied to fabric, heat must be applied to produce the puff effect. used straight from the pot, it will give you a white print, pigment inks can be added to the puff binder to make a coloured print, but will only make a pastel shade as the paste is already white.
The health and safety with this is to keep the heat gun aimed at the table and not to get your hands in the way of the heat and not to have it aimed at anyone else or yourself as it is quite hot.
The Process
Place the puff binder on the screen just above the image. Place the squeegee in the paste, then put the blade behind the pasted bring the squeegee towards you with slight pressure bringing the ink forwards and covering the image. then take the ink back up again, two pulls on the squeegee should be enough.
once printing is complete the screens need to be washed. Firstly the excess ink needs to be scraped off the screen and put back in the pot. Then, take the screen to the wash out area and wash both sides of the screen with the hose pipe. once the screen is clean it needs to be placed in the drying cupboard to dry, this should take around 15 minutes.
Once the fabric has been printed and the screen washed, heat needs to be applied to the fabric. Using a heat gun, lightly wave the heat over the fabric, until the print puffs up.
Health and safety Screen printing - Gloves and aprons must be worn. Try and avoid spillage and splashing. Leave area clean and tidy. wash away any unwanted dyes or inks. wash hands before leaving the print room.
Health and safety puff binder - Be aware of hot surfaces when using the heat gun. Wear protective rubber gloves and apron. Be aware of wet floors in wash out area. Try to avoid spillage and splashing. Leave area clean and tidy. Wash away unwanted dyes and inks. Wash hands before leaving the print room.