Making sure our colours don’t run …

Have you ever washed something and realised too late that the dye wasn’t fast? Imagine how that would feel if the object you were washing was over 400 years old. So it’s pretty brave to wash a historic tapestry don’t you think? With over 50 tapestries under our care a tapestry wash is something we plan for very carefully with a lot of testing beforehand to make sure that the dyes don’t bleed.

Here at Historic Royal Palaces’ textile conservation studio we have a purpose-built washing facility, the only one of its kind in the UK and large enough to hold one of the 5m x 8m Abraham tapestries from Henry VIII’s Great Hall. You can learn more from reading our previous blog posts and see a video of a tapestry wash here

One of the many challenges faced during a tapestry wash is to ensure that the dyes don’t run. Traditionally, tapestries were woven with naturally-dyed threads which tend to be stable when wet. However, during their long lives many of our tapestries have been rewoven or restored; the synthetic dyes used in this restoration over the past 150 years are more likely to bleed.

Accurately testing these threads is really important. Before washing the lining is removed from the tapestry which means that we can take small samples from the loose threads on the back and place them onto a grid that replicates their position on the tapestry.

2017-05_SamplingThreads

The threads are tested using the same conservation-safe detergent that will be used for the wash. Samples are placed on blotting paper and covered with wet cotton wool then left overnight. Any excess dye will then bleed out and stain the blotting paper. We then repeat this using clean water to simulate the rinsing process. If dye bleed occurs, we look at its original location on the tapestry – if it is from a dark thread next to a light area of tapestry we need to be very careful!

2017-05_Pipetting

If the risk to the tapestry is too great then we may have to decide to find other ways to clean it. If not then the risk can be minimised by speeding up the drying process. This is when dyes bleed the most as different areas of the tapestry dry at different rates – thicker, more densely woven areas will stay wet for longer and thinner areas will dry out faster. This can cause the dye to be wicked from the damp areas into the drier areas. Blotting the excess water with large towels and positioning cold air fans around the tapestry reduces the drying time enormously.

Blotting with towels

Nikki Chard, Textile Conservator

Blog link: http://blog.hrp.org.uk/conservation/bathing-hercules/

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