Making a ‘Mulberry’ Corner Cabinet – Part Eleven

While waiting for other substances to dry on the show wood, I dealt with colouring and protecting the cabinet’s exposed external pine surfaces with a minium wash.

It became common practice in the eighteenth-century to wash the back boards of case furniture with minium (red lead); its opacity disguised the (often second grade) pine boards and its toxicity was an effectual insecticide against attack by furniture beetles.

Lead, in its various forms, has been known to man for thousands of years and the Romans, who employed it in abundance, were all too aware of its toxic nature, naming it morbi metallici. The Romans also gave the name minium to lead tetroxide, after the area by the Miño River in northern Spain whence it was extracted from naturally occurring deposits (minium can also be produced artificially from a solution of lead nitrate and sodium hydroxide).

Natural lead tetroxide.

Minium pigment.

When new, minium is the brightest orange imaginable, however, after spending maybe, three hundred years on the back of a chest or cabinet, next to a damp wall, chemical reactions with the atmosphere, other compounds in the wash and chemicals within the wood itself, can render the original orange colour anywhere between salmon pink and chocolate brown.

Coffer with a minium-washed pine back.

A heavily oxidised minium-washed corner cabinet back.

A sulphur-rich environment can turn minium virtually black.

I made up a pot of minium wash, comprising an extender, a binder and several edaphic pigments (to help simulate the natural oxidisation of an aged minium wash) and brushed it liberally over the external pine of the two cabinet tiers.

The lower cabinet exterior sporting its minium wash.

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About Jack Plane

Formerly from the UK, Jack is a retired antiques dealer and self-taught woodworker, now living in Australia.
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10 Responses to Making a ‘Mulberry’ Corner Cabinet – Part Eleven

  1. Tico Vogt says:

    That is very interesting! I’ve never heard of minium before but have certainly seen examples of it. An insecticide wash, how fascinating.

    Thanks.

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  2. walkerg says:

    I too find this interesting. I’ve seen secondary wood in period examples with this but always thought it was normal oxidation. I’m curious, is there any way to determine that minimum has been applied versus just the natural aging? My thought is that untreated secondary wood exposed to light and air would be more of a drab gray, is that correct? Also, do you know how it might effect poplar (tulip poplar) a commonly used secondary wood used in the US? Can you share your source for minimum or do I need to find my own river bank to dig?

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    • Jack Plane says:

      George, Uncoated pine (or in your case, poplar) back boards will oxidise and any grain patterns will diffuse over time, creating a mellow, uniform surface. However, with wood that has been coated with minium – or any pigmented wash for that matter, the grain will be partially or completely obscured dependant on the concentration of pigment in the wash.

      I have little experience of Tulip Poplar; the only poplar I’ve come across has been in French and Italian period furniture and it was definitely on the grey side as you mention. Raw pine typically mellows to a honey-brown colour.

      Lead products are (quite rightly) frowned upon these days and sourcing white and red lead for restoration/conservation purposes has become extremely difficult. I would contact local museums, old fashioned art supply stores and possibly some chemical companies for small quantities. Alternatively, if you want to try your hand at making minium, I could email the recipe to you.

      JP

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  3. walkerg says:

    We used to use a red lead compound in my days in the shop to aid in the hand scraping of machine slides and ways. A thin coat of red lead on part to be scraped and a thin coat of prussian blue oil paint on the mating surface. Rub them together and the high spots show clearly. I would appreciate your recipe if you wouldn’t mind. Occasionally I am asked to do a “to the letter” reproduction. Might be handy to have this. You can send to Georgewalker.design@gmail.com
    Thanks

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  5. Sid Rickets says:

    That hole in the back of “A heavily oxidised minium-washed corner cabinet” makes me wonder: 18th century VCR?

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  8. Just stumbled on this article. Sorry for such a late reply.
    For anyone reading this who is interested: boat builders used red lead below the waterline for all of the same reasons furniture builders did. Some suppliers still carry it: http://www.traditionalboatsupplies.com/consumables/leadbasedproducts/red-lead-powder

    Regards,
    St.John

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