How Do We Introduce New Materials into Daily Conservation Practice?
 |
One of the most difficult and least discussed aspects of conservation practice is deciding when and how to introduce a new material into our daily work. We tend to inherit recipes, solvent choices, and treatment approaches, initially from our teachers, and then from the literature, often without questioning the historical context in which those materials were adopted. Yet conservation is not static. Materials age, health and safety standards evolve, and our understanding of material interactions continues to improve.
Tape stain removal is a good example of this dilemma. For me, it has always been a particularly frustrating treatment. If adhesive residues remain, even partially, the result feels unresolved. Historically, the literature offered effective solutions (dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloroethane), but these were associated with significant toxicity. Conservators have often prioritized personal safety over treatment efficacy, accepting partial stain reduction rather than risking exposure to highly toxic solvents.
At some point, that compromise becomes worth re-examining.
Looking for Equivalents, Not Replacements
Rather than searching blindly for “safer” solvents, I find it more productive to look for functional equivalents, that is to say, materials that behave similarly from a solubility standpoint but carry fewer health risks. This is where the Teas solubility parameter diagram becomes a powerful decision-making tool.
The Teas solubility parameter diagram has been criticized in conservation for oversimplifying complex material interactions, and this criticism is warranted when the diagram is treated as a predictive or prescriptive tool. However, when used as a comparative framework rather than a recipe, the Teas diagram remains a valid and useful approach. It does not predict treatment outcomes, but it helps identify solvents with similar solubility behavior, narrowing the field of candidates that warrant careful testing. Used in this way, it supports informed decision-making without replacing professional judgment or empirical evaluation.
TEAS diagram (Triangular Equilibrium Analysis of Solvents) translates Hansen solubility parameters, dispersion (δD), polarity (δP), and hydrogen bonding (δH), into percentages that can be plotted as a single point in a triangular diagram. Solvents that cluster near one another tend to behave similarly in practice.
When viewed through this lens, a clear candidate to be used instead of DMF emerges: dimethyl sulfoxide (DMSO). Widely accepted in paintings conservation but still relatively unfamiliar in paper conservation, DMSO plots very close to DMF in the Teas diagram. This proximity explains why it performs so well in situations traditionally addressed with DMF, without carrying the same level of toxicity.
Testing Before Trusting
Of course, identifying a promising material is only the beginning. Introducing a new material into conservation practice demands professional judgment and a disciplined testing strategy. While conservators in private practice may not have access to full laboratory facilities or the time for extensive analytical testing, this does not lessen our responsibility to proceed methodically and critically, using the tools available to us. My approach is intentionally conservative and sequential: I begin by testing on new paper, where any immediate or delayed alteration can be clearly observed. If the material proves stable, I then move to aged paper specifically selected for testing purposes. Only after these steps have been completed, and the material’s behavior is well understood, do I consider its use on the actual artifact.
In general, solvents are relatively innocuous to paper. They penetrate the fiber network and then evaporate, leaving no residue behind. That was my observation with DMSO as well—both on new and aged papers. The greater challenge was not the solvent, but controlling its movement.
Control Is as Important as Chemistry
Even the “right” solvent can become problematic if it migrates beyond the intended treatment area. For that reason, controlling diffusion is essential. Traditional solvent gels, as those used in paintings conservation, were not an option here due to their dark coloration, which is unsuitable for paper treatment. Instead, Klucel G proved effective in thickening DMSO, allowing localized application while remaining fully reversible through water removal, either by immersion or on the suction table.
This step, modifying delivery rather than chemistry, is often overlooked when introducing new materials, yet it is critical to making them viable in real treatments.
Weighing Risk Against Long-Term Damage
No material enters conservation practice without raising questions. In the case of DMSO, I observed slight swelling in some papers. This inevitably leads to a broader discussion: how do we weigh minor surface changes against the long-term consequences of leaving adhesive residues in place?
Tape residues do not remain stable. They darken, embrittle the paper, and eventually lead to losses. A slight alteration of surface texture, by contrast, is just that—slight. From a long-term preservation perspective, removing degrading residues offers a clear advantage. The object that has been thoroughly cleaned will almost always age better than the one burdened with residual adhesive.
A Model for Introducing New Materials
This process, identifying functional equivalents, analyzing them using solubility tools, testing incrementally, controlling application, and evaluating long-term risk, is not limited to tape stain removal. It offers a model for how new materials can be responsibly introduced into daily conservation practice.
Innovation in conservation does not require abandoning caution. On the contrary, it demands more of it. But when approached systematically, introducing new materials is not a gamble; it is a necessary part of keeping our practice both effective and sustainable.
