When we first unrolled the bundle of architectural drawings, it felt like opening a time capsule. These weren’t ordinary sheets of paper — they were made on linen drafting cloth, a tough, translucent fabric once considered the gold standard for architects and engineers. From the late 1800s until the 1960s, this was the material of choice before polyester films took over.

The drawings had clearly lived full lives. They had been carried to building sites, pinned to walls, folded, rolled, and handled countless times. What reached our table was fragile and tired: stained with oils, covered in grime, creased from years of rough storage, and dotted with reddish-brown foxing marks. The ink lines — the very heart of the design — dissolved at the touch of water.

Why Linen Was Both a Blessing and a Curse

Drafting cloth was valued for its strength. Unlike paper, it could survive the wear and tear of fieldwork. But its smooth coating, made from starch or gelatin, also made it vulnerable. Moisture could ruin it, insects and mold loved it, and ink would sit only on the surface, ready to smudge away with the slightest contact.

More about Drafting Cloth (“linen”)

While “linen” as a primary support was required for all United States government contract work in the 1950s, it was widely used as a support for architectural and engineering drawings from circa 1850 to 1960 when it was replaced by cheaper, durable polyester films. Drafting cloth was manufactured in Lancashire, England and exported all over the world. The substrate was a linen or cotton fabric and could be bleached, then filled or coated with starch, gelatin or, more recently, synthetic compounds. Sometimes the completed drawing on drafting cloth was coated with lacquer-like coatings, including nitrocellulose, which resulted in a very brittle support. A glossy coating on one or both sides created a smooth surface that is translucent rather than fully transparent. Drafting cloth is seldom used today because of its high cost and limited availability. Also, it was formerly required for deposit with building inspection departments as a permanent copy, but is no longer.

Inherent Problems

• The textile substrate is very durable and will withstand much abuse. However, a starch or gelatin filler/coating can be destroyed by moisture resulting in distortion, opacity, exposed fibers, and limpness.
• The starch or gelatin coating renders drafting cloth susceptible to damage from mold, insects, vermin and foxing.
• Heavily filled/coated: Ink and watercolor will not penetrate drafting cloth and, therefore, their application is not permanent. May be washed off with moisture or smeared if handled poorly.
• Storage and handling: Rolling, folding, and poor handling techniques crack the coating and will cause it to wear off gradually. Eventually, the cloth will fray around its outer edges.

Documentation and Testing before designing a treatment methodology/plan

As the very first step, we documented the condition of the drawings. We took photographs and videos. We also tested the solubility of the ink(s). The ink was found to be water soluble.

 Treatment protocol designed and adopted

Understanding the material  and the deteriorating agents I started brainstorming and drafting a treatment plan which was tested and finalized after minor improvements. Following is the summary of the steps followed.

1. We first of all thoroughly dry surface-cleaned the drawings from back and front.
2. Then, we carefully fixed the ink with the help of Paraloid B72
3. Then comes the most important step of cleaning the document with gel that has a specific pH and chelating agent  to pull out the iron ions in the foxing stains. This had to be performed very carefully without touching the inked areas. This cleaning was done both at the back as well as front. The gel had to be rinsed off with deionized water with the help of swab sticks. Keeping a track of the time for which the gel sits on the stain is also very crucial.
4. Overall cleaning with a milder version of the more fluid gel was used to clean the surface followed by rinsing with deionized water. This was very effective in removing the grime.

The action of the chelating agent pulled out the metal ions in the stain and magically removed them. Chelators are chemicals that bind metal ions, rendering them more soluble. In foxing treatment, chelating agents like EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), or citrates are used to sequester iron and other metals from the stained paper fibers. Removing or deactivating iron is crucial because iron(III) can catalyze oxidative browning; by chelating iron (especially after chemically reducing Fe³⁺ to the more soluble Fe²⁺ form), the source of discoloration can be extracted.

What We Learned

Conservation is never just about cleaning an object — it’s about listening to what the material is telling you. These drawings had endured decades of rough handling because of their durability, but they also revealed how fragile beauty can be beneath the surface.

Every project teaches us something new. With these drawings, we discovered how science, patience, and respect for history come together to preserve fragile memories for the future.

This project has been a rewarding journey for our team, and we look forward to sharing the final results soon.