Reflections on Restoring an Art-Deco Lamp and Disguising Pits

It has been a busy week at Antique Bronze. I’ve completed an Art-Deco lamp which had been hit by a lorry and am finishing the restoration of a small bronze- plated sculpture scarred by galvanic corrosion.

Damage to an Art-Deco Lamp hit by a LorryThe Art-Deco lamp will have some follow-up posts as there were some difficulties I had when restoring it  – particularly trying to find the perfect filler. I usually mix my own with bronze dust and polyester resin, but this wasn’t suitable for this particular object. Finding a good copper-alloy filler that will take a patinated finish,  won’t corrode the bronze, and has some flexibility in it,  will be a future mission. Watch this space!

The small statue was interesting as it had a raised corrosion layer much like a form of bronze acne. Other than these small pimples, the surface was in good condition.  The cause of the corrosion originated with something acidic being sprayed across the statue’s surface, which etched the thin brass layer and caused a reaction between the two differing metal layers that made up the statue’s form: an outer layer of brass with an inner core of iron. Read more about galvanic corrosion on Antique Bronze’s blog.

Corrosion on a bronze
Galvanic corrosion on a plated statue

The corrosion was hard and I found the best way to remove it was by breaking its structure using a very fine file,  but as the corrosion broke up, it revealed a small pit. Now the struggle was how to lesson the disfiguration of the pitting. Re-surfacing the statue would be one way, but that’s highly interventive and not my approach. I tried mixing some pigment with a hard beeswax to fill the crevices, but as the surface was otherwise smooth – any slight excess of wax was detectable. Instead, I warmed the surface to drive off any moisture and applied soft clear wax into the pits using it like a filler. The soft wax was easier to wipe from the surface so didn’t result in the same build up as the hard wax had. Leaving it to harden, I later burnished and reapplied another layer. Finally, I lightly stippled with a little wax tinted with earth pigment over the pits and the results are shown below.

pitting harmonised
Pits are harmonised

 

 

A Cheap Trick To Prevent Metals in Storage Being Damaged by Volatile Gases – (Notes to Self Series)

Acid-detector strips can be included in packing containers and work well to detect volatile organic gases by using a reflectance spectrophotometer. I love the fact that analysis tools sound like they’ve been invented by one of the writer’s of Doctor Who. If you haven’t come across one of these little devices before, click here to read more.

Organic gases such as acetic and formic acid are particularly damaging to lead and copper alloy objects so these very inexpensive strips which show results within a couple of days could save significant damage occurring to an object.

Damage to Lead from Organic Vapours

Damage to Lead

They do not provide direct readings, but change colour to indicate the range of pH being encountered i.e. blue to green to yellow as pH becomes more acidic.  They are sensitive to higher levels of relative humidity, but much less so with low RH. They are tolerant of quite a wide fluctuation in temperature.  They should not touch the object, but being inexpensive can be placed around the container to help to identify gas sources.

Full Article by Stephen Hackney. Colour Measurement of Acid-Detector Strips For The Quantification of Volatile Organic Acids in Storage Conditions. Studies in Conservation 61, Sup 1, 55-69. 2016