Most common plastics hold up fine against ammonia, especially the diluted household kind. Ammonia won’t eat through your typical plastic bucket, spray bottle, or storage container. But the answer depends on which type of plastic, what concentration of ammonia, and how long the exposure lasts.
Which Plastics Resist Ammonia
The plastics you’re most likely to encounter in everyday containers, bottles, and bins are generally safe. Low-density polyethylene (LDPE), polypropylene (PP), and polycarbonate all rate as resistant to ammonia at both room temperature and up to 140°F (60°C). Both LDPE and HDPE show little or no damage after 30 days of constant exposure to ammonia at temperatures between 68°F and 122°F, according to chemical resistance testing by Professional Plastics.
Polypropylene is one of the best choices for ammonia storage or repeated contact. It’s the plastic used in many chemical-grade containers, and it holds up across a wide temperature range. LDPE, the softer, more flexible polyethylene found in squeeze bottles and plastic bags, also performs well.
There is one notable conflict in the data: one major compatibility chart from Thermo Fisher rates high-density polyethylene (HDPE) as unsuitable for ammonia, while another testing source shows it handling 30 days of constant exposure without visible damage. If you’re storing ammonia long-term, polypropylene or LDPE are the safer bets. For short-term use like cleaning, HDPE is unlikely to cause problems.
Plastics That Ammonia Can Damage
Clear plastics and acrylics are the main concern. The American Cleaning Institute specifically warns against using ammonia or ammonia-based cleaners on plastic windows and storm doors, because the ammonia can cause streaking inside the plastic. This isn’t a surface mark you can wipe off. It’s a chemical change in the material itself.
Polycarbonate is an interesting case. While compatibility charts rate it as resistant, lab research tells a more nuanced story. X-ray analysis of polycarbonate surfaces treated with ammonia shows that chemical reactions alter the surface, making it more absorbent to water. For a storage tank, polycarbonate works. For a clear window or lens you want to stay pristine, ammonia cleaners are a bad idea.
Household vs. Industrial Ammonia
This distinction matters more than the plastic type in many cases. Household ammonia is a water solution containing 5 to 10 percent ammonia. Anhydrous ammonia, used in refrigeration and agriculture, is over 99 percent pure. The two behave very differently when they contact materials.
At household concentrations, ammonia is relatively gentle on plastics. You can spray an ammonia-based glass cleaner on most plastic surfaces without worry, provided you’re not soaking acrylic or clear polycarbonate panels. The water in the solution dilutes the chemical activity enough that brief contact with nearly any plastic is harmless.
Anhydrous ammonia is a different story. At near-pure concentrations, it becomes aggressive enough that OSHA limits approved container materials to iron, steel, certain rubbers, and specific plastics rated for the job. If you’re working with concentrated or anhydrous ammonia, you need to check the exact plastic type, not just assume a container will hold.
Rubber Seals and Gaskets
If you’re storing ammonia in any container with a rubber seal, the seal is often the weak point, not the plastic body. Several common rubber types fail badly with ammonia:
- EPDM, neoprene, and butyl rubber: All rated satisfactory for anhydrous ammonia. These are your best options for gaskets and O-rings.
- Viton (fluoroelastomer): Rated unsatisfactory across every form of ammonia, from cold gas to liquid. This is a common high-performance seal material, so it’s an important one to avoid.
- Polyurethane: Also unsatisfactory. Ammonia breaks it down.
- Silicone: Fair for anhydrous ammonia, satisfactory for cold ammonia gas. Acceptable in a pinch but not ideal for long-term contact.
Temperature also shifts the equation for rubber. Cold ammonia gas is compatible with almost every elastomer except Viton and a few specialty types. Hot ammonia gas, however, degrades most rubbers to some degree, with only EPDM, neoprene, and butyl holding up at a “fair” rating.
Practical Guidelines for Common Situations
If you’re cleaning with a store-bought ammonia solution, standard plastic spray bottles, buckets, and containers are fine. The concentrations are low enough that the plastic won’t degrade in any meaningful way. Just keep ammonia cleaners away from acrylic sheets, plastic windows, and clear polycarbonate panels.
For storing ammonia solutions longer term, polypropylene containers are the most reliable choice. They resist ammonia at both room temperature and elevated heat. Look for the recycling number 5 (PP) stamped on the bottom.
If you’re working with concentrated or anhydrous ammonia for agricultural, industrial, or refrigeration purposes, use only containers and fittings specifically rated for ammonia service. Check that any rubber seals are EPDM, neoprene, or butyl. Avoid Viton seals entirely, despite their reputation as a premium material for other chemicals.