Friday, March 8, 2013

T M I !



I'm currently teaching a six week evening class (at CIT formerly Central TAFE) on simple printing on clay techniques plus a few surface decoration mehods not commonly taught in an evening class e.g. Mishima, Sgraffito, sprigging and the like.  I write this knowing that some of my readers are also potter/teachers so I regard my blog as a discussion - feel free to chip in.  I usually teach this class in a one day workshop, mostly demonstrating, and it is pretty intense covering about six or more topics.  Breaking this down into small segments for two and a half hour classes has been a thoughtful process for me.  I've observed that students seem to want the instruction followed with time to try it out, with me within reach as necessary.  I factor in late arrivals, traffic and parking hassles and the fact that people need time to tune out their work day and into the class as something they've signed up for as a pleasure.  They prep some clay slabs as students gradually arrive, we settle into the mindset and the motivation is high. It is challenging to figure out how much depth into go into as each technique requires certain materials, certain tools and it is important to understand the process of what is happening with the materials in practice.  The class is a mixed lot, some are very up to speed on clay things and some aren't, but really want to be, so I have to modify my instruction accordingly.  Feedback indicates that I hit the right groove in general.  I set out to cover one technique and, having covered the basics I then cover the range of options with that technique.   I dread addling the class with Too Much Information or TMI and putting them off.  My aim is for them to go home feeling they've learnt and understood the process.  The reward is when the place falls silent and you realise the whole class is totally immersed in having a go.  While my students are in the handbuilding area Andrea Vinkovic is on the other side of the spacious open studio teaching her throwing class and her students also fall silent in their concentration.  All we hear is the hum of the wheels.  It is so satisfying.


I'm told that most galleries here won't accept work which uses the Japanese or Chinese printed tissue prints so popular in the last few years, due to the market being cornered by a handful of ceramists who excel in this method.  So we are learning to make our own tissue prints - less perfect than bought ones but unique to the maker.  

This week we covered Screen printing with Underglaze.  The image has to be put onto a screen creating a stencil on the mesh for the 'ink' to be squeegeed through onto some tissue or clay.   We covered the range of screen options, I favour Riso Screens (or Gocco) for their ease of availability from Jacksons Art Supplies here in WA.  You just provide a PDF on a thumbdrive, email your image or simply hand it in to a Jacksons branch to get it made.  We looked briefly at Diazo photo sensitive emulsion type options which would take a whole term of classes to teach well - and is sometimes taught at TAFE.  We mentioned that there are screen prep services who'll take your silkscreen, expose your artwork onto the screen resulting in a very durable screen - permanent until you need a new design put on it.  
image from NEHOC website
Then there's the superb StencilPro - a pink photosensitive pre treated mesh from the US you can expose in sunlight in a short time now available from Nehoc in Sydney, NSW.   We have lots of sunlight in Western Australia (surplus in fact, my dear snowed in Canadian friends).  

For 'ink' options - we ran with mixing powdered underglaze and low melting fritt with a suitable print medium.  For the medium I prefer, Derivan Print Gel, you can buy it in art shops or use honey or corn syrup or even condensed milk - as long as it can soak up and carry the pigment powder and screen it through the mesh.  A Curtin Uni print student contributed the condensed milk suggestion.  I am steering away from oil based media for now as the mess and cleanup might be off-putting.  I'll post on that another time.

Ratios of pigment to medium depend on the composition of the powdered underglaze - and some are 'thirstier' than others.  You want to create a densely pigmented syrupy 'ink'.

Ditto with the ratio of underglaze powder to fritt - some underglaze compositions melt more easily than others - so I unapologetically tell the class - there are no easy answers, you have to test test test!  I am awaiting some premixed black ceramic ink to test right now from Northcote Pottery Supplies in Melbourne but that will be another post.

As for colour options, there are some superb premixed liquid underglazes available from Walkers, Cesco, Northcote, Duncan and Amaco to name a few brands.  They come in a plethora of colours, but their viscosity is too low for use in screening.   In fact these products can be used by rendering them thicker/more viscous through evaporation and that elusive ingredient - patience, of which I have heaps.  Essentially most print on clay techniques are very similar to printing on paper or textiles, it is just the 'ink' that differs in composition as it has to survive being applied to clay - flat or otherwise, bonding to the surface and being fired.  The best prints are 'just' screened and applied while the ink is still wet to some moist leatherhard clay.  On Weds night we were only practicing on recently made slabs but the night was warm so they were stiffening up fast despite covering them with moist Chux/J-cloths prior to use.  Transferring a recently made print on tissue paper onto a complex curve means trimming the tissue around the print area carefully for ease of application.  In theory it is easy but in reality it takes an understanding of the process and some dexterity.  Fortunately ceramic artists seem to thrive on developing these things.  

I am preparing a short slideshow for my class next week, not something I'd usually do for an evening class but I want to inform and excite my students and 'set them on fire'.  

Let's see what all the other potters are doing at http://mudcolony.blogspot.com.au

PLEASE NOTE: All text in this blog posting is copyright of Elaine Bradley, Ceramic Artist, Western Australia unless quoting from another source.  All photographs in this blog posting are copyright of Elaine Bradley unless otherwise stated.  No responsibility can be taken for external links.  Please report any errors in crediting photographs, sources or facts to the author in order to allow her to rectify the matter.  Your response or feedback is welcome.

3 comments:

  1. All sounds so interesting - one day I'll come over to see you for lots of ceramics chats. Hope the class goes well, looking forward to seeing some results.

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  2. Hi.....I found you via Mud Colony.

    Diazo is definitely not for beginners. Once you learn the process it's just a matter of doing the steps in order.....but..... Karo is okay but bugs love it and it's always tacky. What kind of tissue do you screen on? I have used newsprint; tracing paper warped badly. I'm slowly getting interested in screen printing again.

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  3. Agreed Smartcat. Great system once you know the process and sequence - not something you'd do in an ad hoc way. When Laura McKibbon was teaching a workshop here in Oz a few years ago she covered making the riso oscreens BUT we were working outdoors with special bulbs to expose the screens. She underestimated the power of the sun in Australia, some screens got too much light before the lamp process so it all got a bit difficult. I avoid Karo (which I think we barely even know here in Australia, and honey's viscosity differs according to temperature so on a 40 degree celcius day it'd be too fluid. I love using Tylose aka CMC (carbomethylcellulose aka wallpaper paste without the antifungal stuff in it) though, very good stuff but only suitable for small batches as it loses its properties over time. You know hairgel might do the trick too. I just buy the cheap tissue paper from the artshop at 10c per sheet. it has a smooth and a slightly rougher side - and print on the rougher side though it makes little difference, I must see if it any cheaper from a bulk packaging outlet. I have used that tough paper handtowel stuff you get (filch) from public toilets and butcher's paper aka newsprint (sans print). The tissue works for me. There is a good source in the US for printing ink for ceramics though - now I have to go and find it. I'll mention it here when I figure which site it is.

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