Apothecary Vase

Steve Bisco delves into the dark art of fuming oak

There is something about the word ‘apothecary’ that conjures up the image of an ancient sorcerer pouring steaming potions from a dark vase, broad and bulbous at the base and narrow at the neck, with a stopper to keep in the magic. Well, in this project we are going to use a little sorcery to turn a pale piece of ordinary oak into something dark, mysterious and ancient-looking. There are no wizard wands or magic words involved (unless you feel so inclined) but you will see the oak, sealed inside a transparent container, change colour before your very eyes in the space of a few hours.

This strange alchemy is achieved by the process of fuming with ammonia. The oak is sealed in a container with some liquid ammonia, from which the gas given off reacts with the tannin in the oak, causing it to become much darker. This replicates the process of ageing that occurs naturally in the wood, but at the rate of about a century an hour. In a few hours our pale new oak will be back in the Dark Ages. The colour will be the same all over, unlike the effect provided by wood stains, which tend to soak into end grain and give an uneven colour.

In case you are worried, the ammonia we use for this project is household ammonia – not the industrial stuff. It is sold in hardware stores as a domestic cleaning fluid and is generally between 5% and 10% ammonia. It is strong enough to darken oak but is safe to use if you follow the manufacturer’s safety instructions. Just use it in a well-ventilated space, wear eye protection and gloves to protect from splashes, and stand at arm’s length to avoid breathing in the fumes.

Making the apothecary vase starts by turning the outside of the vase and its stopper as one piece, then the stopper is parted off. The vase is hollowed through the narrow neck, first by drilling with a 13mm drill in a Jacobs chuck, then using a spindle gouge and a ring tool to open out the inside. The vase in its natural oak colour looks ‘pale and interesting’, but with the aid of a household cleaning product (or magic if you prefer) we turn it into something ‘dark and mysterious’.

Materials and equipment used

• Oak, 95mm square x 200mm
• Household ammonia
• B rown wax polish
• S pindle roughing gouge
• Spindle gouge (with ‘lady’s fi nger’ grind)
• B eading tool
• Flat and round-nosed scrapers
• Ring tool
• 13mm drill

Safety

Ammonia is an irritating and corrosive chemical and even at low dilutions can cause irritation to the respiratory tract and skin. Any splashes to the skin should be washed immediately with copious amounts of water. Splashes to the eye should be cleaned using a First Aid kit eye wash and medical attention should be sought.

Children are particularly susceptible to respiratory damage from inhaling ammonia. • Ensure the chemical is never mixed into any liquid bleach or chlorine-containing products as a toxic gas may result. Appropriate PPE is a must when working with ammonia products.

Sourcing Oak

I have used 95mm square oak (4in nominal) for this project. It is not easy to source anything thicker as kiln-drying only works up to 4in thick. If you can get some air-dried oak in a larger size, by all means make it bigger. Green oak that has been air-dried for at least three years is much nicer to work than fully-dried oak, but it has a tendency to carry on shrinking, warping and splitting when brought indoors, so you have to decide how much of that you are prepared to allow. If you use old oak from fence or gate posts (as I did), plane the surface and check carefully for nails, staples and anything else that may damage you or your tools.

DID YOU KNOW

The effect of ammonia fumes on oak was discovered many years ago when people noticed that oak beams in stables and pigsties darkened much more quickly than oak used in houses. It was realised that the fumes from the animals’ urine, rich in ammonia, were the cause. The Victorians liked their woodwork to look dark and ancient, so they took to exposing new oak to ammonia fumes to achieve the medieval look they so desired. Only wood that is high in tannin will respond to fuming with ammonia. The sapwood of oak – the whiter and softer outer layer near the bark – has no tannin and will remain pale, so make sure your oak is all heartwood. However, you can get some very interesting mottled effects by fuming oak burs that have swirls of sapwood among the heartwood and then turning them into bowls.

Shaping up

Turning the detail

Fuming

Finishing

Further reading

PHOTOGRAPHS COURTESY OF STEVE BISCO