What Are Safer Alternatives to Toxic Label Removers?
RAPID RESPONSE Request: Can you identify a safer chemical, other than muriatic or sulfuric acid or methylene chloride, that will remove stubborn ink/printed labels from bottles.
Request by: Idaho Manufacturer
One of the product lines manufactured by an Idaho company is unique glass items made from used bottles. The manufacturer cuts the tops off of bottles, grinds any rough edges, and then re-sells them as drinking glasses, windchimes, candle holders, and a variety of other products. All previous labels and ink or printing must be removed from the bottles prior to re-use.
Labels and some of the printed ink labeling are easily removable with benign chemicals, water, and/or elbow grease with scouring pads and scraping tools. However, some bottles have very stubborn ink, possibly thermally bonded to the glass, and nothing seems to be able to remove the labels except muriatic or sulfuric acid. High strength methylene chloride fails on some of the labels. (See photo).
In the case of two of the company’s bottle suppliers, the labels are so persistent that they actually leave a “ghost” image on the bottle, even though the paint has been removed. The company is concerned about occupational exposure, odors from the storage area of these chemicals, and hazardous waste generation.
Blasting or etching of the adhered ink is not acceptable because it leaves a frosty surface on the final product.
Safer stripping products easily remove most of the inks on the bottles, depending on the type of ink and how it was applied. To remove strongly adhered inks, the company, with assistance from Idaho DEQ, is testing different products in a chemical alternatives replacement analysis. To date, none of the safer alternatives tested have worked, although they may need to retest some of them at the exact set time and temperature specifications for the stripper.
The California Department of Public Health, Occupational Health Branch has published a guideance poster listing active ingredients in stripper products, from “safest” to “avoid”, and also provides information on the affects and protective measures. Their safest recommendations for preferred stripping agents benzyl alcohol, soy, and dibasic esters. They suggest using the following With Caution: sodium hydroxide, magnesium hydroxide, and calcium hydroxide. Then, because of it’s listing on California’s Prop 64 list, N‐Methyl pyrrolidone (NMP) is suggested to be used with Extreme Caution. Finally, Not Recommended, are toluene, methylene chloride, and methanol. The document does not provide guidance on d-limonene, or use of acids, the latter of which the Idaho company is currently continuing to use for the stubborn labels. Some people have serious allergies to d-limonene products.
Disclaimer: PPRC does not endorse or guarantee the performance or safety of any specific product, chemical, company, or brand mentioned herein. Any products selected for testing or use must follow safety and use personal protective equipment (PPE), and/or vented fume hoods, as directed on MSDS or SDS/spec sheets.
The following products were recommended from various users, including automotive fleets, or others that have tried these products or types of products. Some of these strippers may take more time to work than others and have different optimal temperatures for removal.
- Benzyl alcohol-based stripper, e.g., Piranha NexStrip Zero VOC Paste, or SmartStrip.
- (See Bathcrest case study using SmartStrip)
- Benzyl alcohol-based stripper with formic acid, e.g., Piranha NexStrip Pro
- d-limonene-based products, e.g., GooGone®
- Auto metal polishing compound, e.g., Autosol®
- Soy-based strippers, e.g., Instrip, SoyGreen®,
- Dibasic ester based stripper, e.g., Safest StripperTM
- Calcium/lime/rust remover*, e.g., CLR (See information from a home brewer below).
- See additional suggestions from California Department of Public Health’s Guide to Choosing Paint Stripping Products: Safety Considerations (ranked from “preferred to “not recommended”)
*Some calcium, lime and rust removers contain hydrochloric acid.
Home brewers tend to have a similar challenge removing ink labels. This YouTube video shows a calcium, lime, and rust remover called CLR, (reportedly containing glycolic, sulfamic, and citric acids and surfactants) that easily removes some painted labels on beer bottles. We could not find the concentration of the ingredients in this product, or a verified listing of ingredients, or occupational safety hazards. If this product is effective, we recommend getting all the product and safety information from the manufacturer prior to use.
Some brewers also suggest soaking bottles in a Coke or Pepsi product for days to expose them to phosphoric acid.
Additional product suggestions can be found at the Toxics Use Reduction Institute’s (TURI) CleanerSolutions Database. TURI provided a safety score on each of the products with 50 being the maximum score and safest product. When they test products, they also consider how it will be used, e.g., immersion, ultrasonic cleaning, etc.
Additional Safety and Exposure Recommendations
- Avoid falling for greenwashing about “safer products” just because the product literature or labeling says “safer”, “biodegradable”, “green”, or similar marketing terms.
- If a product is found that does work in removing labels, research the chemical or ingredients of the product in the OSHA Database of Chemical Hazards to ensure all safety precautions are taken during use. Additional hazard and exposure information can be found at ToxNet (see ToxNet results for sulfuric (a carcinogen) and muriatic acid)
- Tightly seal all containers and store in secondary containment.
- Use the lowest concentration possible. For products that demonstrate effectiveness, experimentation may prove that lower concentrations will also work.
- Use chemicals at the specified temperature for maximum effectiveness.
- If an acid is the only viable solution, some acids decompose at a slow rate, so some gas (e.g., sulfur dioxide from sulfuric acid), is unavoidable. Acids can corrode storage containers. Spills can occur during use as well. Exterior rinsing of bottles and cabinet maintenance are recommended.
- Also, for acids and caustics especially, ensure appropriate PPE is used at ALL times, including face and arm protection, especially with acids, to protect from splashing or spills.
- PPRC does not recommend sulfuric acid (CAS 7664-93-9) as it is considered a carcinogen (Jersey Department of Health Right to Know factsheet).
Results / Conclusion
The Idaho company is currently experimenting with some of the above alternatives but has not settled on a final solution for the more stubborn labels. This case study will be updated if any new successful alternatives are found. Please contact PPRC if you have additional ink stripper suggestions.