Lessons in Acid Dyeing Lessons in Acid Dyeing
10 August 2022

Lessons in Acid Dyeing

Written by: Sara Thornburg

For the past month I have been ruminating on the color black. The sum of all additive pigmentation, and the absence of light. There are as many shades and tones of black as of any other color, though most don’t pay them any mind until they’re trying to coordinate a wardrobe of nothing but. In my freshman year color theory and painting class, our instructor had us construct our palette with an array of colors. Multiple yellows and orangey-reds, blues, purple, browns, white, but no black. He encouraged us to mix our own using the other colors on the palette, which gave us greater control over the subtleties of shadows and helped train our brains to interpret those slight changes of temperature that give the darkest areas their life.

The black on my mind of late was for my current project at Harpers Ferry Center. A nineteenth century tailcoat in need of conservation. I have been working on custom dyeing fabrics to match the black of the coat to rebuild a large area of loss in the tails. The loss is large enough to distract from the rest of the coat. Creating a visual compensation for the loss will allow the park it belongs to to display it for the public without compromising how well it can tell its story.

Custom dyeing in the conservation lab is much more precise than dyeing at home. The actual amounts of dyes and additives are based on the weight of the fabric being dyed and are meticulously measured and recorded before being added to the dye bath. A recipe needs to be created that can be scaled up or down to give the exact shade wanted for the project. These recipes also allow for the dyes to be recreated for future projects without doing a bunch of test swatches first. As recipes are collected, they can used as a starting point when trying to mix a new dye color for a project. For example, if you have a red you need matched you’d flip through the book and find a red close to what you need, then tweak the colors to give you what will hopefully be a perfect match.

The tailcoat I am working on is made of wool with a silk lining. Both of these fabrics are made of protein fibers that are dyed in a slightly acidic dyebath at high temperatures over about an hour and a half. The temperature is slowly raised throughout the bath until it reaches its peak, then kept there to ensure the dye has fully and evenly reacted with the fabric. The process takes a full afternoon from precleaning the fabric to giving it its post-dye rinse and wash. Any miscalculation can result in a splotchy dye, a too light, or even too dark color.

My own adventures in custom dyeing have resulted in mostly failures, as black is one of the hardest colors to dye due to its darkness. I ran through three trials with the silk, each time the fabric came out much too light. I did finally get a nice black after overdyeing a previous sample. The wool came out perfectly the first time. Of course, these were just my sample swatches, so I’ll be returning to the dye pots soon to dye the fabric I’ll be using on the tailcoat.

Agency: National Park Service


Location: Harpers Ferry Center for Media Services

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