TLCs – a state of change

Back to the future….. Since starting my research I have always relied on the effect of the sun as the major activator for the colour change in my TLCs. Of course, the amount of change depends on the weather conditions, time of the day and season and, while I appreciate the unpredictability of the natural variants, I started to think about the flexibility of having the glass installation installed in front of a wall or in the middle of the room instead of against a window.

So, I started to look for ways to heat the glass electrically and I tried incorporating ITO coated glass in the lamination with TLCs (ITO is a transparent, electrically conductive coating that is applied to the glass and will heat up if an electric current is applied).

Unfortunately, I am now entering the unfamiliar territory of electronics and I have serious problems understanding many of the technical details… Anyway, I did some tests using ITOGLASS 12 (12 ohms/square ITO) and got some effective results as this video shows – Glass Changing Colour with TLCs

To apply electricity to the glass I used conductive adhesive copper tape, conductive paint or metal mesh. Since glass is transparent and all of these will be visible, it is important to position them in such a way that they become a decorative element of the overall design..

It is interesting to see how the heat spreading over the glass depends on the different locations of the electrical connections.

Before I commit myself to a specific method I also want to try using ITO Polyester film coated on one side with some TLCs instead of ITO glass. Another option worth trying is to laminate a Thermal-clear Transparent Heater to the glass. The major problem with all these options is that the materials are very expensive and, generally, have to be imported from the US. I’ve been trying to exercise my charms to get suppliers to let me have small samples instead of having to buy complete sheets, but I am rapidly running out of favours!

I’ve booked a space for a solo exhibition at the Devon Guild of Craftsmen next year to show what I have been doing, so I am now under pressure to actually get some work completed and ready to show!!

Having got frustrated with a lack of progress with the TLCs this week I decided to switch my attention to another project hoping to finish it in time for the Summer Exhibition at the Devon Guild. Some time ago I bought three boxes full of old glass photographic negatives (I am always attracted by everything in glass!) from a charity shop in France. “Plaques séches au gélatino-bromure d’argent” it says on the cover. They are mainly portraits of women, posing in a formal way typical of pictures taken at the beginning of the century and create a fascinating insight into the social history of the period, but there are no details about the identity of the sitters.

Probably they are wearing their best clothes for the shot. Details such as the background in front of a window outside a house with the same chair and window that appear in most of the negatives, build a narrative in my imagination. They probably form the archive of the photographer and I have decided to make a glass construction with part of this precious archive, a collection of forgotten faces.

The portraits will be incorporated inside small glass pyramids that, once put together, will form a kind of hanging tapestry.

Getting the angles of the edges of the pyramids just right will be crucial to ensure that the sides are well bonded when I construct the pyramids. Unfortunately, geometry and maths have never been my strong point, but I think that I have found a way to calculate the angles. I’m now facing lots of boring grinding and UV bonding before I can start on the the final assembly of the construction. I have decided to call it “The other face of the moon”…. (Don’t ask me why?)

In order to address the compatibility problems of the TLCs with the silicone, I have decided to try a different lamination process using EVA (Ethylene-vinyl acetate) film. Initially, I approached a commercial company to do some tests for me, but it was clear that they weren’t really interested and I have now invested in procuring a silicone vacuum bag and a vacuum unit so that I have the freedom to do as many tests as I need with my own facilities.

From the tests done so far it is evident that the EVA film is less heat conductive than silicone, but doesn’t appear to show any signs of incompatibility. Perhaps this was a turning in the right direction through my maze!

I started testing the use of TLCs with glass about 1 year ago and, at the beginning, it was essential to understand the properties and limitations the TLCs provided, to choose the ones that would have the most effect and would add that element of interaction in the glass applications and that I had in mind.

There are various kinds of TLC with all different characteristics. Some are oily and work well once mixed with silicone which can be applied by spreading them on the entire surface of the glass to be laminated. Others are water based soluble designed for spraying which offer lots of potential in creating specific designs.

In general, all the TLCs worked well and were responsive to changes in temperature as I had hoped. However, after a few months I noticed that where the sprayable TLCs were used delamination was starting to occur meaning that there is an incompatibility between the silicone and the TLCs.

The compatibility of the TLCs with the silicone is the biggest issue that I have to resolve and I am now looking into alternative methods of lamination as well as using different binders for the sprayable TLCs.

Inevitably, when experimenting with new materials there are some promising and exciting results, but also lots of frustrating dead ends. Sometimes I feel like I am walking in a labyrinth, with a centre I aiming for, but many blind turnings I have to attempt to go down before I can find my way!

I strongly believe that behind a creative work there is always an emotional intention, even at a subconscious level, no matter how complex the technical process of fabrication will be.

I started experimenting with using TLCs with glass about 1 year ago and to summarise the results of the tests carried out over the last year is not an easy task because everything including all the small details and the failures all contribute to the eventual achievement.

For those with a scientific interest, I have provided some technical information about TLCs and some references for where to find more information. My apologies for making this seem like a college thesis and I hope it is not too tedious!

All the TLCs used were supplied by LCR Hallcrest http://www.lcrhallcrest.com; one of the few manufacturers of thermochromics worldwide and who have been supporting my research.

TLCs show their beauty when looked against a dark background and, when working with glass, this could be a limitation. However, I thought I could make use of this limitation as part of the glass installation design; a laminated glass panel containing some TLCs when viewed against light, say from inside to outside of a window, would show the colour of the glass, but when viewed from outside to inside, with no light, the design made with TLCs would display the changed colour spectrum according to the ambient temperature of the environment, adding a new design dimension.

This was the concept that I wanted to achieve and I started to do some experiments with some samples of TLCs provided by LCR Hallcrest.

Hoping to find more technical details that would help me with my tests, I read the PhD Thesis by L. Worbin (Department of Computer Science and Engineering – Chalmers University of Technology – Gothenburg, Sweden 2010), W. Ibrahim (Heriot-Watt University – School of Textiles and Design – 2012), S. Robertson (Heriot-Watt University – School of Textiles and Design – 2011), M. Ledendal (Heriot-Watt University – School of Textiles and Design – 2015). Although they all are very interesting, they cover different aspects of the application of TLCs mainly within the field of interactive textiles. Glass, of course, is a different medium and, consequently, requires a completely different approach.

In my next post I will describe the results from some of my initial tests.