Showing posts with label Stains. Show all posts
Showing posts with label Stains. Show all posts

Friday 13 March 2009

Silver Stain as a Colour Modifier

Silver stain can also serve a useful purpose to modify the colours of glass. If you add a silver stain pattern to a piece of light blue glass, for example, the result will be a green pattern. This creates all sorts of creative opportunities, particularly when used in conjunction with etched flash glass.

It is also possible to use the silver stain successfully with other paint and enamel colours to warm the colours.

Thursday 12 March 2009

Silver Stains - Mending Mistakes

If the stain did not take, there are techniques to try and improve the colour.

One is firing the silver stain face down on a sifted and smoothed out bed of whiting or thick ceramic fiber paper.

Another is to re-apply your stain and fire again between 675°C (1250°F) and 760°C (1400° F). The higher heat will help the silver stain "take" to the glass. Fire the silver stain face down because the higher temperature will melt the high fire tracery and matting resulting in kiln-wash sticking to the painting.

A third method is to use hydroflouric acid to remove the stain and so start again with clear glass. Remember this is an extremely dangerous chemical.

After a second successful firing, be sure to discard the loose whiting or shelf paper from your kiln-shelf as any residual silver stain absorbed during the firing can result in yellow spotting on your glass on later firings.

Wednesday 11 March 2009

Firing and Cleaning Silver Stain

After the silver stain has completely dried, the glass is ready to fire in the kiln. Remember to fire silver stained items separately from other painted glass. The maturing temperature is between 509°C (950°F) and 565°C (1050° F). Place the glass on the kiln shelf with the painted side down and the silver stain facing up. Fire between 509°C (950°F) and 537°C (1000° F) for softer glasses, and to between 537°C (1000° F) and 565°C (1050° F) for harder glasses. The higher temperatures in each range will result in darker colour.

After firing and cooling remove your glass from the kiln. The glass will look exactly as it did when you first placed it in the kiln, as though it hasn't fired. In fact, the firing process will have done its job, but first you must remove the residual layer of gamboge gum. Simply spray with window cleaner and wipe off. Underneath, your glass should be stained some lovely shade of golden yellow.

Tuesday 10 March 2009

Applying Silver Stains

Introduction
Contrary to its name, silver stain actually stains the glass yellow. Silver stain is available in shades from pale yellow to deep orange. Today the use of silver stain remains a popular choice for the glass painter with no other pigment matching its delicacy and wholly translucent quality. Silver stain is composed of silver nitrate and gamboge gum, a resin from Southeast Asian trees. It is sold in powdered form and is mixed only with water. A separate set of tools is required for silver stains as the stain itself is terribly corrosive to brushes and other tools.

Application
To use, the artist mixes the powdered stain on a glass palette to a thin consistency. This can either be applied thinly in a free-hand manner to the back side of the glass painting, or applied and quickly blended to smoothness with a badger blender for a more even result. Always apply the silver stain to the back side of the glass - in other words, the opposite side from the one that bears the tracery and matting you have previously completed. There are several reasons for this, but the primary one is that the silver stain will metallise the black and brown paint work during firing if applied to the same side. This metallising results in a strong bluish and opaque haze on the tracing and matting.

During application, be sure to work rapidly and evenly, finishing before the wet stain has a chance to completely dry. Also remove the excess stain while the stain is still damp. Scraping off the run-over will prove to be quite a challenge if you let it dry. When you have completed these steps, immediately wash your tools.