- How do I clean laboratory glassware?
- What constitutes a hazardous material?
- What is the best way to dispose of chemicals used in conservation procedures?
- Where can I order conservation and lab supplies?
The principal cleaning problems with laboratory glassware are:
- Solvent-based resins and their residues (e.g. Acryloid B-72)–thick resin residues can be softened by adding more solvent to the bottle and letting it sit until the layer softens and can be removed mechanically. Thinner, tougher layers can be washed out with solvent, or the entire vessel or tool can be soaked in a covered container of solvent, and then washed with soap and water. If the dirty vessel is washed in water before the solvent/resin residue has a chance to dry, the residues will not cling to the glassware as tightly, and can be removed with soap and water and a non-scratch scrubbing pad or bottle brush. The contaminated solvent should be poured into a beaker lined with a polyethylene bag, and left in a fume extraction hood to evaporate.
- Waxes (e.g., microcrystalline wax for coating metal) can be thinned with mineral spirits, or softened in a hot water bath. In extreme cases, the laboratory oven can be used to heat the wax and container so that the wax residue can drain out. The container can then be cleaned with solvent or soap, water, and a non-scratch scrub pad.
- Residues from aqueous or alcohol solutions of reagents used for treatment or cleaning (e.g., benzotriazole in ethanol or EDTA or salt residues in water). Any unknown residues found in containers should be considered toxic until proven otherwise. If they are water or solvent soluble, use the appropriate solvent to soften or re-dissolve them, and pour that residue into a bag-lined beaker for evaporation, or into a storage jar for liquid disposal. For additional safety, rinse the empty container once with more clean water or solvent, and add that rinse to the rest of the residues. Use appropriate safety equipment to avoid splashing or inhaling dust. For additional safety, rinse the empty container once with more clean water or solvent, and add that rinse to the rest of the residues. The glassware can be cleaned with soap and water as above if there are no further residues.
- Insoluble residues and stains left over from the evaporation of hard water (carbonate and silicate precipitates, iron corrosion stains). Many of these can be removed by soaking them in an acid solution (2% hydrochloric acid. After soaking, the glassware can be washed in soap and water, or put into the laboratory dishwasher.
Make sure to always check frequently on glassware that is soaking. Do not leave for an extended period as this may damage the glass. Ensure that any work with solvents or acids is done in a fume extraction hood with appropriate personal protection equipment (gloves, mask, eye protection, apron or lab coat). Remember to dispose of the wash and solid residues appropriately-they may constitute hazardous wastes.
The U.S. Government has written specific laws and regulations that define what hazardous materials are, and how they should be handled. Most of those regulations are laid out in the following Code of Federal Regulations (CFR): Environmental Protection Agency (40CFR Subchapter 1, parts 260-370), Department of Transportation (49CFR Subchapters A, B, C, parts 106-178), and the Occupational Safety and Health Administration (29CFR Section 1910).
Under these codes, there are two basic ways to determine if a material is hazardous.
- Its physical characteristics match any one of the following:
- IGNITABLE: ignites and burns easily or causes other materials to burn.
- CORROSIVE: attacks and corrodes metal or destructively attacks any living tissue.
- REACTIVE: explodes, detonates, or produces toxic vapors under certain conditions.
- TOXIC: contains a toxic constituent that can leach into the environment. Also anything that poses a substantial present or potential hazard to human health or the environment.
- ACUTELY HAZARDOUS: fatal or capable of causing irreversible or incapacitating illness to humans in low concentrations
- The regulations have several lists of specific chemicals, metals, and by-products of industrial processes that are defined to be hazardous.
Most common conservation solvents and reagents fall under one or both lists.
Knapp, A (1993) Hazardous Materials Health and Safety Update, Conserve-O-Gram 2/1
Many chemicals used in artifact conservation are toxic, or pose physical or environmental hazards (i.e. flammable solvents, corrosive solutions, heavy metal residues). All these chemicals and their disposal are regulated by the US and state governments under the Environmental Protection Agency (40CFR subchapter 1, parts 260-370), Department of Transportation (49CFR Subchapters A, B, C, parts 106-178), and the Occupational Safety and Health Administration (29CFR Section 1910). The notes below are summaries, but you must check the actual regulations for compliance.
Under these regulations, NO-ONE using or handling chemicals is exempt from properly disposing of hazardous waste materials (except for household products, even though they are usually just as strong and toxic as the industrial materials).
If you are generating very small quantities of waste (less than 100kg per month), you are exempt from the regulations about registering with the EPA, and the required paperwork documenting the disposal, but you are NOT exempt from disposing of the wastes properly.
If you are generating larger quantities of waste, you will need to get an ID number from the EPA, and you should contact a licensed waste hauler and disposal company. These companies can be found on-line, or in your local Yellow Pages, and your state environmental department probably keeps a list of state-licensed contractors (see also the list of suppliers attached to this FAQ).
The most important things to know about your wastes are:
- exactly what material you need to dispose of,
- how much you have.
There are a few things that you should never do:
- Never pour solvents (even water-miscible ones like ethanol) down the drain – explosive and toxic gases can build up in drain traps and septic systems.
- Never allow containers of solvent to simply evaporate – this is in violation of EPA clean air standards, and can create an explosion or fire hazard.
- Never put toxic, caustic, or corrosive materials, or heavy metals, into a landfill. This will create an environmental hazard, and could affect the health of the landfill workers.
- If you’re on a septic system, don’t pour anything into it, since you’ll probably kill the bacteria that keep the system functioning.
That said, there are a number of ways to legally dispose of small amounts of chemical wastes, and some of them are relatively low-cost:
- Contact a local college or university chemistry department, or even the local high school – they usually have a standing contract with a licensed disposal company, and may be willing to accept your wastes for disposal.
- Contact your local municipal or county recycling center or landfill – most centers now have ways to dispose of paints and solvents (e.g. the solvent and resin wastes from consolidating and coating fragile objects), oils, and heavy metals (lead batteries, mercury).
Contact your local water authority – many wastewater treatment plants can accept caustic solutions (e.g., sodium hydroxide or sodium carbonate solutions for desalinating metal) or acidic solutions through the normal drain systems. They might need to know when and how much you are dumping, so they can compensate.
There are a number of companies that supply tools, chemicals, resins, and other supplies for conservation. A lot of standard laboratory suppliers also sell suitable materials and tools (usually in bulk, and often cheaper). See the list of suppliers attached to the end of this FAQ.
Storage Materials Suppliers
Copyright © 2006 Colleen Brady, Molly Gleeson, Melba Myers, Claire Peachey, Betty Seifert, Howard Wellman, Emily Williams, Lisa Young. All rights reserved. Commercial use or publication of text and graphic images is prohibited. Authors reserve the right to update this information as appropriate.