Introduction to Printed Textiles with Sean Henneberry
Sean started by pointing out the main differences between screen printing on fabric and screen printing on paper – for fabric: no half-tone and a more open mesh, typically using a mesh count of 45-60 threads/cm, rather than 125+ typical for printing on paper and other non-fabric.
He described the screens, aluminium frame, polyester fabric, machine stretched off-site. The fabric print room has similar facilities to the general screen print room, namely
- drying box which is also a light box
- screen photo exposure room (uv light to expose photo sensitive coated screens)
- washout room with pressure wash and trough
- screens up to 130cm x 55cm
It also has
- a dye mixing area
- industrial heat press for transfer print
- steamer cabinet (for fixing dyes)
- dye winch
- print benches which have a slightly soft surface
Sean mentioned room the (room OC8) Digital Print Area which has large inkjet and laser printers.
A range of fabric printing processes are available, starting with Direct Style Printing, a process which is usually used with light fabric and darker ink. Ink is acrylic fabric medium with dye mixed in. This, Sean explained, stays on the surface of the fabric when printed. The acrylic medium is quite viscous, having about the consistency of double cream, which prevents it from diffusing through the fabric even though it is water-based.
NB. Fabric painters often use a thickener (epaississant) such as carrageenan (a seaweed derivative commonly used in food) with dyes for a similar purpose. (Kennedy,J & Varrall,J, Fabric Painting, 1994)
Sean digressed slightly to talk about dyes; he mentioned some of them
- Procian – have good affinity with cellulose fabric (viscose, bamboo) and work well with cotton and silk, I use these.
- Direct- using a hot (near boiling point) dye bath. Used on cotton, wool, silk, leather and nylon
- Acid – neutral to acid dye baths, wool, nylon and modified acrylic, not for cellulose fibres
- Dispense – water insoluable, used for mainly polyester
- Mordant – there are both natural and synthetic types, they all require a mordant to help fix the dye and improve light fastness; often toxic
- Thermochromic pigmants
- Phosphorescent dyes
- Heat Transfer Sublimation (HTS) – workshop available
but stressed that this a a complex area, that not all dyes are compatible with all fabrics, and that different print processes may require different dyes. Sean mentioned that he runs a workshop specifically about dyes.
- Discharge print – essentially a ‘bleaching out’ process, probably not using chlorine bleach as this is inclines to damage fabrics, other substances are available, e.g. Jacquard Discharge Paste
- Illuminate discharge – illuminating dyes have a high resistance to bleaching
- Devore or Burn Out – used on mixed fibre fabric, uses aluminium sulphate to remove cellulose; timing is critical in this simple process
- Seersucker/Crepon Crimp – Fabric, light 100% cotton is printed with thickened sodium hydroxide solution and then immersed in water. Only the printed areas shrink and a ‘crimp’ effect is created
- Flock – as seen on pub wallpaper, an adhesive is printed and fibres are removed with the adhesive, creating a texture
- Foil – large range of colour and translucency, uses adhesive and heat-press – workshop available
- Bonding Techniques – uses stretch and print over double fabric creating an effect, “similar to Bondaweb”, a commercially available heat-sensitive adhesive interface
- Expantes or Puff Binder – uses a plasticised ink which expands with the application of (indirect) heat to give a deep texture
Sean illustrated the above with images and then went on to discuss
- unlimited colour range as per the computer screen
- low waste (according to manufacturers, although there is some controversy regarding this,discussed at Screen printing vs Digital)
- ease of use
- economical for short runs or one off, the fastest growing area of fabric printing
The production of photographic silkscreens handout
We then discussed the photo-screen process, re-iterating that the ‘half-tone’ photo process is not used for fabric, the photo dots being lost in the large mesh. Sean explained how shades are obtained from mono-colour and showed us charts. The use of Folex and acetate was explained and the process of making a resist, just the same as the previous workshop on screen printing.