Enamel Test Strips
I'm really excited because I've just taken delivery of my (early) Christmas present to myself! I really wanted to test out some of the transparent Ninomiya and Nihon Shippo Japanese enamels which are known for their beautiful colours. In particular I was interested in the pink colours as they can react badly to silver and I was advised that the Nihon Shippo pinks in particular were less likely to react.
I spent a whole day making test strips and I thought I would give you an insight on how I make these. It's important to make test strips because enamels react differently to the most common materials used for enamelling - copper and silver.
Firstly I made some strips from copper about 3.5cm long with a hole drilled in the top so I can add them to my colour board. I use copper because it's a relatively cheap metal. In the photo below the strips are having a nice bath in pickle (acid) to remove any surface stain. After this I neutralise them in bicarbonate of soda and clean them off. At this stage I try not to handle them with my hands because finger grease can cause problems with the enamels.
Organisation is not a word normally associated with me (ask my husband!), but if you're making more than one test strip at a time (below) you don't really want to get them mixed up so it pays to try to keep things in order!
I decided to enamel six strips at a time. The little drawing below shows the four firing stages. I split each strip into quarters. The enamel colour will be layered straight onto copper; onto copper coated with copper flux; over silver foil and lastly over silver foil coated with silver flux. Other enamellists also test their colours over white enamel or gold foil. Reds in particular can look very lovely over gold foil; blues look gorgeous over silver.
For the first layer (see photos below) I wet packed the enamel colour over the first top quarter of the metal strip and wet packed the rest of it with copper flux. I dried the enamel out in front of the kiln and then I fired it for about 1 and half minutes at about 800 degrees celsius.
There are two things I should explain. Firstly, enamel 'flux' is not the type used in soldering. It is a clear enamel that is often put over the metal first. Secondly, wet-packing simply means putting the enamel on using distilled water. The enamel must be dry, however, before it goes in the kiln. I wick most of the water off with paper towels before they go in the furnace. Enamel can also be dry sifted over metal as necessary.
The photo below shows the test strips after they have been in the kiln for their first firing. You can see how the transparent enamels react with copper over the top quarter of the strips. On the bottom three quarters the copper colour shows through the clear flux.
For the second layer (below) I wet packed the colour over the second quarter (over the copper flux) and added a piece of fine silver foil over the third and fourth quarters.
For the third layer (below) I wet packed the enamel colour over the third quarter (directly over the silver foil) and silver flux over the fourth quarter.
For the final firing (below) I wet packed the colour over the fourth quarter (over the silver flux) only.
The photos below shows the finished test strips after they had cooled down. The first thing I do is label the back of them with the colour and code. These correspond to a file on my computer on which I list their firing temperatures and any special notes about them. See, I am organised really!
These test strips show each enamel's suitability for firing directly or indirectly (over flux) on copper and fine silver. I especially love Ninomiya's 348 blue-purple (top middle.)
I do this with all of my enamels because you can never tell how they will react with different metals just by looking at them in a tube. Plus they look so pretty hanging on a colour board and it's easier to pick colours off and compare them for use on a new piece.
Until next time.