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Zinc-based organ pipes need gilding

2003

I am an organ builder in Boston with a somewhat unusual request from a customer. They have an organ with visible pipes in the case which they want to "gild" to match other architectural features in the building.

These pipes have never had any kind of finish applied. From appearance and normal organ building standards, I would say they are made of mostly zinc, with possibly some small lead content. They have, I guess, oxidized over the years (about 25 years old) and have a uniform dark gray color. I would gold-leaf them (very tedious - commercial gold leaf comes in very small sheets and these are big pipes), or even easier, just spray paint them.

But the question arises as to surface preparation - do not most "gold" leafs and paints contain metals other than gold? Do I have to worry about any galvanic action eventually corroding the pipe or its new finish? Or can some kind of primer be used to eliminate this problem, if indeed it is a problem?

James Swist
pipe organ building - Boston, Massachusetts

In your situation I would investigate about a conversion chromate coating to find if it is suitable for the base metal and if it renders an acceptable color. Any coloring based on metallic overlays will pose the danger of galvanic corrosion to the base metal since gold and zinc are the two most apart metals in the galvanic series. The alternative of gold color painting might be possible after a suitable thorough cleaning, polishing and priming with an impervious barrier to avoid contact between the zinc and any metallic particles in the paint.

Guillermo Marrufo
Monterrey, NL, Mexico
2003

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2003

I would use gold-leaf. Nothing looks better than gold-leaf, even gold plate. It's richer and deeper. It also protects the metal. I would use Le Franc slow (use quick size when you get better - more production) size to apply it. If you're a beginner, use Patent leaf. If not, use loose leaf. It looks a little better. Gold-leaf will last forever, if you don't touch it. It dulls with contact and scratches easily, but the scratches are easily re-gilded. There are special clear-coats available from sign suppliers to reduce these problems, but they decrease the beauty of the gold. Preparation probably involves some light hand-sanding. With patent gold and quick size, you can gild on site and avoid handling the fragile gold. You can buy everything you need from a sign-supply company.

Here's how to do it.

Clean the metal and wipe with a tack rag. If there are any places you don't want the gold to stick, put a thin layer of talcum powder on everything. Wipe or blow it off the gold areas, but a little bit doesn't hurt. Apply the size with a proper-sized soft natural brush to the areas you want gilded. The size is clear, and some people add a bit of Imitation Gold, One-Shot sign paint, in order to see where they haven't yet painted and to color any "holidays", or small voids in the final gold. Wait almost the specified time for the size to get tacky. A few hours for quick size and overnight for slow size, if you size late in the day. Test in an unseen area by gently rubbing your knuckle against the size. When ready, a squeak will be noticed. With quick size, your window of gold application opportunity is several hours. With fast size, it is much less. Only size as much as you can gild in one session. Smooth out any drips as you go along, since the size gets sticky very quickly.

Next, apply the gold. Apply loose gold with a guilder's tip and patent gold simply by removing a sheet and pressing the gold into the size. The object of both is to get complete coverage. Don't worry about what it looks like at this stage. If the gold doesn't stick well, you may have waited too long and will have to resize. Sometimes, it will not stick because it is too cold. Warm up the room or, maybe, use a hair dryer ⇦this on eBay or Amazon [affil links] . The work should go quickly, since on something as big as organ pipes, you can use full sheets. Don't worrying about using an excess when using loose leaf. If you start cutting little pieces, it will take forever. Just slap it on. If there are voids, slap on another sheet. If you use patent, you will use less gold but it will take longer.

When all is covered, take a very soft brush (I use a 1" red sable) and gently scrub the gold. Push any excess into places you've missed. Magically, all the gold pieces fuse together and the excess separates as a powder. Also, it burnishes the gold. You can also burnish with 100% cotton, medical cotton balls. Remove excess powder by light blowing or with a damp cotton ball. Let it cure for a few days. That's it. "Gold paint" is nearly always made up with brass or bronze powder, both of which are mainly copper. All produce an weaker and poorer color than real gold.

If the other architectural features are colored by artificial gold, they will pale in comparison and may be overpowered by the gold-leafed organ. In this case, you may want to forget everything I've said and find a matching "gold" paint.

Hope I've been of help.

Chris Owen
- Houston,Texas