Lye and chemical staining

Overview

Chemical stains react with wood chemistry rather than depositing colour. The one documented here is lye: Fine Woodworking #273 (Puro) uses 100% lye drain cleaner dissolved in distilled water on cherry. The lye reacts with the wood to give rich colour without blotching. Related reactions are in Ebonizing (iron and tannin) and Ammonia fuming (ammonia and tannin). Potassium permanganate is sometimes mentioned for chemical staining, but no source was checked for it, so it is not covered here.

Pros

• Rich colour on cherry without blotching (Puro).
• Puro's recipe uses household drain-cleaner lye.

Cons

• Caustic: NIOSH lists sodium hydroxide as causing burns.
• Results depend on the wood; make a sample board and take notes on the back (Puro).
• Only the cherry recipe was sourced; other woods are untested here.

Suitability

Described for Black cherry. Other species were not covered by the sources and results should be tested.

Coats and application

Puro's cherry recipe, in outline:

1. Dissolve 100% lye drain cleaner in distilled water and apply to the cherry.
2. Seal with SealCoat shellac.
3. Glaze with asphaltum (roofing tar in mineral spirits).
4. Finish with shellac topcoats. The tar glaze is reversible over shellac.

Follow the article's quantities; this entry does not repeat them. Work through a sample board first.

Compatibility

Seal with shellac (Shellac) before glazing (Glaze and antiquing glaze). Compare with Wood bleaching, where lye in a two-part bleach darkens wood first (Fine Woodworking).

Care and repair

A glaze over shellac can be adjusted. The sources do not describe removing the lye colour; test before relying on it.

Safety and environment

NIOSH sodium hydroxide: ceiling REL 2 mg/m3, PEL 2 mg/m3, IDLH 10 mg/m3. Burns skin and eyes. Fine Woodworking says lye bleach can blind and burn. Wear gloves, eye protection and ventilation.

Related

• Ebonizing
• Ammonia fuming
• Wood bleaching