Devoré - paste recipe

Slowly add 40g of Indalca to 500mls of cold water. (using a food processor with a blade attachment ensures a consistently smooth paste)
Weigh 180g of Aluminium Sulphate and add 20g of Glycerine and slowly add to the mixture. (The original recipe for Devoré paste that I used to follow recommended stirring in another 300ml of cold water but I find the resultant paste to be too thin.) Adjust accordingly to your own preference using either more water to thin the paste or more Indalca to thicken. As a general rule of thumb; the paste needs to be liquid enough to penetrate the fibres but without being too liquid to hold its shape when applied to the cloth.

Application: When applying to mixed fibre types of fabrics such as a silk/viscose velvet, apply the paste to the silk backing. This ensures that the paste will penetrate through to the pile at the roots and give a better line definition.
The paste can be applied by a variety of means including screen printing or use of brushes, pipettes etc.... Whichever method, attempt to get an even application of the paste. The applied paste then needs to be dried thoroughly. In a workshop situation this will be speeded up using driers and even then some thicker areas of paste will only be dry on the surface.

Activation: The cloth then needs to be ironed in order to activate the chemicals in the paste resulting in carbonisation. These chemicals will only react with the cellulose fibres (viscose) but leave the silk fibres untouched. If you have made any mistakes at this stage then remember that they will only be apparent if you heat activate the offending areas! otherwise, carefully avoid them.
When fully carbonised, the pile will come away easily. This process should be undertaken in a well ventilated room and a suitable face mask worn. Avoid rubbing too hard if the pile seems reluctant to come away as this could result in a torn silk backing. Just keep applying more heat until the pile comes away easily. This can be achieved slowly with an iron on a moderate heat but don't be alarmed if the dried paste does discolour a little. This will generally come out with the viscose detritus. However, if the paste gets scorched the blackened colour will almost certainly transfer to the silk backing permanently. 

Once the pile has been removed, the detritus can be vacuumed and the cloth can be washed in warm water, rubbing a little soap in the burnt-out areas. Rinse well in cold water, squeeze out the surplus moisture and dry.
The cloth can be dyed whilst still damp. Procion Dyes are effective, giving full hues in the velvet and subtle tones to the silk backing.

Health & Safety Considerations:

Andrew Wynne 2008