The Glass Painting – Enamel Powders (GPP series) are finely ground glass (finer than flour) powders than are meant to be mixed with a medium for application:
- with a brush; (Use a water or oil based medium of you choosing. See below.)
- or mixed with a screening medium for silk screen application; (Use A-8 Screening Medium (pine oil) or A-14 Painting and Screening Medium (water miscible)
- or mixed with medium suitable for air brush application. (Use water or water miscible medium.)
These enamels are low fusing and low expansion. They will fit most glass substrates:
For enamel on copper fire at 1450˚F for 1 to 1-1/2 minutes or until gloss.
For glass fusing, they will attach at 1200˚F, will gloss between 1300 & 1350˚ and could be fired as high as 1450˚.
GPP powders are opaque colors but light will pass through them on glass. Colors are most vibrant on an opaque white glass. They are not as vibrant on clear glass.
Painting and Mixing Mediums:
For dry powder painting enamels and pigments some form of wet medium is necessary to make painting possible. Many materials could be used. The primary requirement for enamel painting is that the medium will not leave any ash after firing or will not create bubbles in the glass after firing.
Painting mediums can be either water or oil based. Water mediums are good for washes, and have no odor when using.
They tend to dry much faster than oil based mediums, shortening the working time.
Oil based mediums allow more working time and they disperse the powder in a more controlled manner. Sharper, thin lines can be achieved. Oil based mediums may need to be ‘smoked’ (as mentioned earlier in the article) before firing, depending on how much oil has be used.
Some of the oil based mediums have a strong pine odor such as Squeegee Oil (A-4), Thinning Oil #5 (A-5) and Screening Oil (A-8). The squeegee oil is more viscous than most of the other oils. It is the oil used in the 900E series – oil base. It is the best oil to mix powders with for use in a crow quill pen.
Thinning oil #5 is a less viscous version of the squeegee oil.
The screening oil is a refined squeegee oil which allows for better resolution and less spreading or blurring of the oil after painting.
Lavender Oil (A-11) is good for fine details and smells like lavender. Clove Oil (A-10) is good for washes and smells like cloves. Painting Oil for Miniatures (A-12) is good for miniature style painting where extremely minimal oil is to be used. It has very little odor.
Water based mediums such as Klyr-Fire (A-1), Agar (A-2), Enamel Holding Agent (A-3) have thickening (body of the
medium) and gum-like (holding agent) properties. Diluted with water (1 pt. water, 1 part medium; or 1 pt. water, 3 parts
medium) these gum solutions make good painting mediums.
They have no odor, however, they dry very quickly. Water based mediums do not have to be ‘smoked’ before firing.
Acrylic Medium (A-13) is a water based acrylic polymer resin.
This medium is slick, has a somewhat viscous body when used full strength. Mixed with painting enamel, the mixture when dry becomes very hard. It is possible to paint over the dried painting enamel before firing. It can be thinned with water as desired. It does not have an odor.
Painting and Screening Medium (A-14) has the best of both worlds – it acts like an oil medium, but is water soluble and has no odor. This medium is most suitable for multi-purpose use. It works great as a painting medium, can be used for screening enamels and works well as a medium for air brushing.
It can be diluted with water. It may need a small amount of ‘smoking’ before firing, but not nearly as much as other oils require.