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Glue Got Me Thinking?!

Hello fellow readers!


I was recently experimenting with removing labels from glass jars to reuse them and use them for my experiments. After several trials, I found that the labels on the glass jars are stuck with glue and a simple brute force effort was not enough to remove those labels!

The results were really ad-hoc, best described; when I tried to peel off the label, some left a residue behind, others left part of the label behind. The most exciting part was that any attempts to remove the label to remove the residue were more labor-intensive than planning to remove the label from step 1 onwards.

Before I share what ways worked best, I did some reading on "glue" and its various uses!


It is interesting to note that various kinds of glues are used for several types of industries. Some of the glue kinds are Liquid glues (Starch, Resin, and Dextrin), Gelatin glues, or Protein Based glues.


The liquid glues are very popular and are used in a wide variety of applications. There are different kinds of liquid glue, such as starch glue that are modified vegetable starches. One common application in a household setting will be to boil corn starch powder to make a thick mixture for craft projects. Remember to use an applicator and ask adults to help with the boiling and mixing process. Manufacturers have found a way to hydrolyze the starch and form a low molecular weight carbohydrate. Dextrin glues are water-based and are easy to use for the paper glue industry. Resin glues are typically used in the construction industry and have applications in woodwork with a long curing time. The name resin is a misnomer and today's industry primarily has only synthetic resin glues. Two types of resin glues are prevalent - thermoplastic and thermosetting. Thermoplastic resin glue never completely hardens and softens or hardens as temperatures fluctuate. Thermosetting glues go through an irreversible chemical reaction to glue surfaces together. Many of these thermosetting resin require different temperatures to operate. Examples of thermosetting resins are Phenol-formaldehyde, Resorcinol-formaldehyde, Urea-formaldehyde, Melamine-formaldehyde. Examples of thermoplastic resins are polyvinyl acetate.

Protein-based or gelatin glues are derived from collagen. Per the manufacturer LD Davis, they use recycled gelatin capsules that usually fill landfills and use for their glue! Talk about creative thinking! I wish we could all think of ways to recycle waste in mass industrial efforts. Typical uses of these glues are the cosmetic industry, photography.


Finally, let's talk about eco-friendly glues: it's common to have glues based on petrochemicals, cyanoacrylate polymers, polyurethane, and epoxy. If not catalyzed and not inert (unreactive with other materials), some of these chemicals can have an impact on human and environmental health. However, some manufacturers are making eco-friendly bio-degradable glues available. Some of the research techniques are also leading to creating new products such as glue for paper straws! Hooray for that.


Did you know that the FDA requires that the labels used on food jars and food packaging be compliant with safety standards! This leads to our initial question on removing labels from glass jars (especially those that came with food such as olives or pasta jars to reuse for storing other items). The technique is simple: completely submerge the jar in hot water and leave for an hour or more. If the label is not peeling easily, then change the water. Usually, magic will happen; however, there may be some scraping of the glue residue left behind on some jars.


Sources:

https://www.fpl.fs.fed.us/documnts/fplrn/fplrn141.pdf

https://www.bobsredmill.com/blog/healthy-living/what-is-dextrin/

https://www.mixerdirect.com/blogs/mixer-direct-blog/how-glue-is-made

https://www.lddavis.com/products/eco-friendly-glue/