Late 19th Century and early 20th Century glass is often found with attached metalwork of one sort of another. This is usually either solid silver, silver-plated, pewter, copper or brass, and can be cast or hand-beaten. Such metalwork was sometimes to provide strength or improve functionality (rims, spouts, handles, feet, flower-grilles, and hinged fittings for things like powder-pots, inkwells etc), and was sometimes purely decorative (frameworks of flowers or foliage - found most often on Art Nouveau glassware)
The usual method of fixing metalwork to the glass was by using Plaster of Paris. This (a) holds the glass snugly within the metal frame, (b) provides a water-resistant seal, (c) is easily replaceable when it becomes broken or discoloured - or if the glass needs replacing, (d) is a very 'forgiving' material, which can be wiped or scraped away very easily if it gets anywhere it shouldn't, and (e) it allows the glassblowers to work to larger tolerance, as it can be used for filling any size of gap. Plaster of Paris can still be obtained from a Chemist (Pharmacy or drugstore) and is found in most Craft shops. In an emergency, Polyfilla makes a reasonable substitute, but the real thing is better. Although we have come across all kinds of substitutes used by amateur restorers (including various glues, and even fillers for repairing car bodywork!), we would always recommend using the genuine article - mainly because it's easier! Here's how to use it:
(1) remove the old plaster from both the metalwork and the glass. Soaking the piece for a few hours in warm water (a little liquid soap may help) will soften the plaster, and should allow it to be picked out. Unless you can trust yourself to go VERY slowly and carefully, avoid using sharp metal tools, as you risk damaging the metal or the glass. Hard plastic is a safer material to work with - you can make your own tools with it, or buy ready-made sculptor's tools (if the plaster is particularly stubborn, you may have to soak it more than once)
(2) separate the metal from the glass. Once most of the plaster has been picked out, the metal frame will loosen. To separate it from the glass, you may need to exert a gentle 'pull' and 'twist', but be very careful not to overdo it! Do NOT try levering the glass out of the frame with an implement - you will almost certainly break it!
(3) clean off any remaining plaster from either piece, then dry them (if you intend to polish the metalwork, this is a good time to do it)
(4) mix some Plaster of Paris and water to a 'creamy' consistency. If the mixture is too stiff, it will not fill in all the gaps. If it is too loose, it may fall out in places, before it has set
(5) apply the mixture to the metal frame, using a spatula, making sure it gets into all the crevices (a toothpick may help to push it into narrow spaces). Be fairly generous when applying the Plaster mixture - it is easier to remove excess than to later refill gaps you have missed! Now present the glass to the Plaster-filled frame and press it in, gently but firmly
(6) allow the plaster to set. After an hour or so (times may vary), the plaster will be set, but has not yet become completely hard. This is the ideal time to:
(7) clean off any excess Plaster, using plastic or wooden tools. Just remove major excess at this point, and take care not to remove any Plaster from inside the frame
(8) carry out a final clean next day, by when the Plaster will have gone hard, using an old toothbrush. Finally, wash and dry the re-assembled piece
As with any restoration technique, slow and steady does it, and practice makes perfect!
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