This chapter discusses all about grain and liquid enamel. The painting enamel information is in the Supplements and Add-Ons chapter. This page lists some infomation that did not make it into the book.
There are different clear transparent enamels (also called flux and transparent clear enamel). Each of the formulas, when fused to copper, affect the color of the metal. Some, like 2030 and 2008, cause the copper to look pinkish. But some make the copper look goldish. My favorites are 2015 Golden Clear and 2110 Wax Yellow (also called Ivory Beige). 2015 is less golden than 2110, but both are really nice. I'm sure all the other manufacuturers have differences, too, but these are the ones I know.
There are three Thompson enamels currently called Crackle Bases - 1006 (White), 1997 (Black) and 2008 (clear). But the actual Crackle enamels are liquid and their name was changed from Crackle Enamels to Liquid Form Enamel colors, to reflect that they can be used for many more things. Here is some information about these enamels. Note that 1020, Titanium White, can also be used for a crackle base.
The ONLY time this line of Thompson Enamel liquids crack are when they are used over the bases (or 1020). If you put any other Thompson unleaded enamel over the bases, they normally produce a technique called Pull Through. It is incorrect and misleading to call this result crackle enamel instead of pull through. They look totally different - one has cracks like rivers and one has dots. Please do not call this Crackle Enamel.
These enamels do not like being in even mild acids such as Jewelry Pickle. They will turn matte and at least sometimes never return to be glossy, even after firing again. Although you probably don't want this to happen, there are times when it could look rather nice as in this piece by Jennifer Bauser, shown in the book on page 45 about layering gold leaf. Jennifer had put the blue in pickle after some soldering and it got all funky and pitted and matte which she totally loved the contrast with the shinny gold leaf so continued to use the piece. The enamel was 1698 Darkest Blue by Thompson Enamels.
This topic is covered extensively in the book, but there is always more to learn. Ora Kuller uses the fact that wet-pack grains straight from the jar will spread when fired. But if you want a wet-packed application to stay where put, use -200 or smaller mesh. Remember, though, that if this is a transparent, it may be more opaque than you want so there is a trade off. Experiement and see what works for you. Also, remember that the higher/longer you fire, the more spread you could get.
The enamel chararteristic of soft, medium and hard is discussed: soft enamels fuse at a lower temperature than medium and medium fuse lower than hard. If you put a soft enamel under a hard enamel, you will probably get pull-through, which may not be what you want. The book mentions that this characteristic is dependent on two things: the enamel's fusion flow number and its softening temperature. Here I give a bit more about this...
Normally, but not always, a low softening temperature and a high fusion flow makes an enamel a soft enamel. Coversely, but not always, a high softening temperature and a low fusion flow makes a hard enamel.
The fusion flow number was obtained in an interesting way. Tom Ellis related that a small pill sized piece of fused enamel is fused to a steel plate. Then the steel is set in a kiln at a certain temperature, say 1450°F, in a verticle position, for a standard period of time. The amount of dripping/flow the enamel causes on the plate is used to determine the fusion flow number.
Enamels with a low fusion flow number (ie: they didn't flow as much) were ones that have a heavier viscosity. Viscosity being the thickness of the enamel when it flows.
Think of this... if you using a high fusion flow enamel on a bowl, because of the flow and the steepness of the curved surface, the enamel will slide towards the middle. Thus it's better to use a low fusion flow enamel on a bowl. This type of understanding will help yu be more successful in enameling.
Expansion (COE) is another characteristic that affects how enamel reacts. The expansion is how much the enamel epands when heated and contracts when it cools. Metal also has an expansion and the expansion of the enamel and the metal must be compatible for the enamel to stay on the metal. That is a primary reason why Thompson Enamel sells different lines of enamel. Note: all the vintage leaded Thompson Enamels are low expansion enamels and the unleaded enamels are higher expansion, which is one reason why if you put leaded under unleaded enamel you will get Pull-through.
All these characteriscs affect how one enamel interacts with another. See the manufacturers specification for these numbers. For Thompson Enamels, see The Thompson Workbook.