Removing old foam glue from metal

Alcohol	vs	Acetone

Something a bit different today - I'm going to log my test of removing foam from some metal hooks I've had for quite some time. I started noticing an issue when, although still sticky, these 4+ year old hooks newly applied to the wall always kept falling down. I realized the glue must have degraded (it will start to degrade after 2 years) - so I bought new double-sided foam tape to use for application. However the foam backing was a bitch to take off...even with a scraper and goo-gone. So I did a bit of research and came up with two solution solutions (get it) which I had on hand.

I did have Copilot help me track the experiment as it went on - and while I do let it brainstorm with me to improve my writing [and when it comes to stuff as the composition and properties I will copy and paste from copilot] - it does not write my posts. For transparency sake I will just mark info which has come from copilot with [CoPi]

Isopropyl Alcohol

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🧪 Composition

• Isopropyl alcohol (propan‑2‑ol): ~91% by volume

  • CAS No.: 67‑63‑0

  • Primary active solvent — miscible with water and many organics.

• Water: ~9% by volume

  • Slows evaporation slightly, improves penetration into porous materials (like foam).

• Trace impurities: May include denaturants or stabilizers depending on brand, but usually negligible in household 91% IPA. [CoPi]

VS

Acetone (Nail Polish Remover)

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🧪Composition & Properties

• Type: Acetone‑based remover — acetone is the primary solvent, but this formula is diluted and blended with conditioning agents.

• Impacting Ingredients:

  • Acetone – the main active solvent; breaks down polymers in nail polish (and in your case, adhesive) quickly.

  • Ethyl acetate – a secondary solvent; less volatile than acetone, can help dissolve residues.

  • Isopropyl alcohol – assists in dissolving and speeds evaporation.

  • Glycerin or aloe vera / vitamin E – moisturizing agents to counteract acetone’s drying effect.

  • Water – dilutes the solvent mix slightly.

• Effect on adhesives: Still effective at dissolving glue once foam is gone, but slower than pure acetone because of dilution and the presence of oils/moisturizers. [CoPi]

The first thing I tested was if I could have Alcohol OR Acetone provide me with a 1 stop... solution...(I'm beating this dead horse) in removing the foam sticker from my metal hooks. So I set up a simple experiment in my beakers.

Test Sequences

1. Alcohol → Acetone

2. Acetone → Alcohol

3. Batch runs

4. Recovery attempts on stubborn cases

Results Summary

Sequence	Foam Removal	Glue Removal	Notes
Alcohol →  Acetone  (single)	Foam lifted cleanly in ~10 min alcohol soak; peeled in one go with fingernails first lifting up a corner, then carefully pulling the whole foam off. Some glue residue was left behind.	Glue wiped off in 90 sec–3 min acetone soak with thumb pad	Fastest, cleanest method; no finish damage
Alcohol →  Acetone  (batch)	2/3 hooks: foam lifted cleanly in ~10 min; 1/3 slower due to crowding in smaller beaker - I think one of my hook backs may have been touching another hook - thus not getting the full surface area treatment.	Glue wiped off in 90 sec–3 min acetone soak	Confirms method scales to batches; crowding can slow foam release
Acetone →  Alcohol	Foam softened but came off in chunks; alcohol stage failed to produce sheet lift	Glue layer not fully exposed; removal incomplete	Slower, more labor‑intensive; poor sequence choice is putting it mildly. -> this became the "test case" in the next row.
Acetone → Alcohol →  Acetone (recovery)	Foam partially removed mechanically; small remnant resisted even after long soaks	Glue under exposed areas softened normally; foam‑covered spots resisted	Residual foam blocks acetone’s glue‑dissolving speed. This is painful because the acetone is breaking down the foam without getting to the glue underneath - meaning it comes off in chucks with a lot of difficulty.

Key Observations

• Order matters: Alcohol first is the clear winner. It wicks between foam and glue, creating a clean separation.

• Acetone first weakens foam structure, causing it to fragment and shield glue from alcohol.

• Glue removal speed: Once foam is gone, even diluted acetone dissolves glue in 90 sec–3 min.

• Batch processing works — but avoid crowding in small beakers to ensure full solvent contact to foam backing in solutions.

• Residual foam is the enemy: Any foam left in place slows acetone dramatically. Even after using a scraper to get most of the foam off...another 10-minute acetone soak barely helped release the glue.

Best‑Practice Protocol

1. Alcohol soak (~8–12 min) → peel foam in sheets.

2. Acetone soak (90 sec–3 min) → wipe glue away easily. If it's not easy with say your finger or thumb pad, soak it another 90 seconds.

3. Rinse & dry — warm soapy water to remove any solvent/oil film.

4. For batches: make sure there is enough surface area for the hooks so the glue backing is completely exposed to the rubbing alcohol.