Products and materials containing methylene chloride (DCM) will be prohibited on the GSD campus, effective June 1, 2025.

This policy change is in response to guidance provided by our colleagues in Harvard’s Environmental Health and Safety (EHS) department and regulations created by the United States Environmental Protection Agency (EPA).

While this chemical has been banned from many products available to consumers in the United States, at the GSD we encounter it in plastic-welding products such as:

When evaluating alternative products, as with any material you intend to purchase or use, consult the Safety Data Sheet (SDS) to determine its Signal Word (SDS Section 2.2) and associated Hazard Categories (SDS Section 2.1). Then follow the GSD Hazardous Materials Flow Chart to determine the conditions for use at the GSD.

This policy change now requires that you also review a product’s chemical components, listed in Section 3 of an SDS. Therein, methylene chloride can be referred to as “dichloromethane”, “DCM”, or under a variety of trade names and identifiable by its Chemical Abstract Number (CAS-No.): 75-09-2. Any products containing this chemical are not allowed at the GSD.

More detailed information regarding hazardous materials used at the GSD is provided in our Hazardous Materials training, a part of the Fabrication Lab Orientation, Waiver and Release Agreement available on the Harvard Training Portal. This training and the Refresher will be updated over the summer to address this and other changes to processes related to fabrication at the GSD.

Dichloromethane Alternatives

In particular, Plastruct Plastic Weld has been a commonly-used adhesive at the GSD when working with acrylic.

While we haven’t identified an alternative adhesive product that works in the same way as Plastruct, we have found some success with others, including:

• Clear (Double-Sided) Film Tape is popular for its strong adhesive quality, ease of use, and availability in multiple widths.
• Instant Adhesives (Cyanoacrylate) when used to “tack” at small discrete points along a joint, rather than along an entire length or between sheets, may be an option when joints are otherwise difficult to tape. Some products may be available in viscosities that are easier to work with than others. Please consult SOP before use.