Technical Information

Carbonold supply and apply a variety of fixing agents for traditional soot wash applications. Many historical soot wash projects are not true soot washes and may have had modifiers added to improve the durability. These can range from additions of standard masonry paints, bonding agents and waterproof sealers at various dosage levels.

It is important to use a compatible fixative. If the wrong fixative is chosen this could result in a severe drop in performance and also the likelihood of unsightly efflorescence or a milky haze.

We can test the surfaces of your brickwork to determine which product would be appropriate for applying new coats to old surfaces.

Along with black ferric oxides we use a particular grade of carbon black which produces the closest match to historical lampblack. It was chosen for its propensity to produce a close match to traditional historical soot washes. Most lampblacks (or Lamp Black) available on the market are too blue, and will not produce anything near a traditional soot wash. The majority are actually Furnace Blacks which are more likely to produce blue tones and not black.

We take great care in sourcing the correct grades and colour test all our carbons against approved London sootwash brick panels.

PURE MINERAL BINDER: We can formulate a soot wash based with a pure mineral silicate fixative which has a rating less than Sd 0.05m. Paints with an Sd value below 0.14m are considered to be Class 1 Vapour Open and to have high breathability performance. When applied to brick and tile the permeability of the surface remains virtually unaltered. Any loss in permeability is too small to measure. The product would contain zero VOCs.

PLANT BASED ALKYD: If the brickwork has be subjected to previous applications of a latex or acrylic based product, then we can formulate an appropriate soot wash which would have an Sd value below 0.12m and contain low to zero VOCs.

REVERSIBLE: Some internal applications on Grade I listed properties may require a soot wash that can be safely removed in the future. We can also formulate a product for this purpose which would possess the minimal amount of rub-off whilst still possessing a reasonable degree of durability.

OTHER WORK: We work on some of the oldest properties in London and can create the most appropriate, sympathetic product to produce a pleasing natural look.