Question about Metaling

Q: Have a Silver Stain question. I have a church piece done by Emil Frei, Jr, 1948. It appears to be Lambert's glass (gray/blue, purple). The Silver Stain has come off the original piece and the church wants it re-stained. There is metaling on the back; how do I remove the metaling?

A: It is very unusual for the silver stain to “come off”. The stain literally penetrates the glass and is as permanent as anything out there. I would be very curious to see some photos. Are you sure it’s stain and not enamel? Anyway to remove the metaling your only choice is a weak solution of hydrofluoric acid – use the proper safety precautions as it is dangerous stuff. I would be reluctant to refire the old glass, my suggestion would be to plate it with a layer of thin float glass – the silver stain takes very well on the tin side of float – you can refer to this illustration from my book:

Restoring a Meyer window

I received an inquiry about restoring a Meyer window. The restorer said he would be using Lambert's glass and had access to Reusche and Keracolor stains. These are the images he sent, scroll down for my reply:

MY REPLY: Looking at your images I wanted to first say that not everything is silver stain. Forgive me if you already know this but only the ornamentation in the diamond quarries is silver stain. The yellow brown tone that appears to be fading off is some other pigment. I have attached a photo with some arrows below.

Not everything is stain.

Silver stain is very permanent as it is absorbed into the glass itself and not subject to corrosion from atmospheric weathering like vitreous pigments are.

As to the silver stain, I made many tests as I was preparing my book on stains. Here is a photo of my test on Lamberts glass: 

My tests on Lamberts Glass

I think you will have the best results with Reusche 1383 or Keracolor using a mixture of 1 part 76050 to 4 parts 73028/A. You will need to experiment to get the density of the application correct. Prepare two identical samples with a heavy to thin gradation application on Lamberts glass. Fire one sample and then you can compare the results to the unfired stain. Stains look radically different after they are fired so a fired/unfired sample is extremely beneficial. You can mix the stain with any medium but using oil may allow you to make a more controlled gradation. Silver stain is best fired between 538C/1000F - 593C/1100F Try this schedule as a starting point:

90 min to 540C/1004F

10 min to 580C/1076F

Hold for 45 min

If the stain is too heavy after firing it can be lightened with a cotton swab dipped in hydrofluoric acid - use extreme caution when working with acid in this way.

If you plan to fire the stain several times - make a test for this as well - stains can intensify during successive firings. I had a stain appear to "not take" once I washed off the clay body (all stains are premixed with ochre/clay). I refired the piece - without reapplying stain and it came out beautifully. Even knowing as much as I do - stains can remain a mystery :)! My best advice is to test, test, test and keep a good log - be scientific in your approach.

Historic Orange Stain

A student sent me these photos of a panel that came into her shop for restoration. I ran into a similar project years ago and was equally frustrated. Here is what I know about orange stain.

I understand from reading: Barley, Keith. “Trials and Observation in the Use of Silver Stain” Stained Glass, the Magazine of the British Society of  Master Glass Painters, no. 1, 1996, pp. 11-13 that there was a glass called "kelp glass" or "staining glass" that was produced in Britain in the 19th century which took silver stain extremely well and allowed the achievement of the red orange color shown in these photos. The silver stain was applied to both surfaces of the glass to double the intensity.

Unfortunately, I do not know of a way to achieve this color today using stains or glasses which are currently on the market. In my own experimentation I was not able to reach a red-orange color only shades of amber-brown.

I came close to the color using gold ruby enamel on one side of the glass and silver stain on the other, but the result lacked the transparency of the historic orange stain. Of course acid etching red or orange flashed glass would be a solution however it was not the way this color was created historically nor would it be very efficient today.

Here is another approach which I have not yet tested:
Debitus produces a copper red stain which in my experiments produces a red color on the tin side of float glass or on glass formulated to be "reactive" with copper and silver - like Bullseye's "Reactive Ice" C.O.E 90 or Uroboros "Red Reactive Transparent" C.O.E 96. Experimentation with this copper stain in combination with silver stain may produce a similiar color result on float glass. I have not tried mixing them together or applying them in layers.

As a side note, I have also petitioned Lamberts Glass to develop a clear glass which takes silver stain better. Clarifying ingredients in their current batch inhibit the development of silver stain. In my tests with Lamberts clear I found that their glass does not take stain as well as some clears produced by other factories. I would encourage others to contact Lamberts as well so they can begin to recognize there is a world wide need for a glass like this in today's market.