How to Easily Identify Self-Adhesive Glue Types
Identifying self-adhesive glue types is straightforward. Based on practical scenarios, I've organized three methods from easiest to most difficult: quick visual/tactile identification, simple tests, and professional identification. All work in workshops, receiving areas, and label inspections.

I. Quick Visual + Tactile Identification (On-Site, No Tools Needed)
1. Water-Based Adhesive (Acrylic Emulsion)
•  Appearance: Milky/semi-transparent layer; even clear versions have slight haze. Dry surface, no sticky stringiness.
•  Feel: Gentle tackiness; rubbing firmly won't produce long strings.
•  Common substrates: Most coated paper, writing paper, and standard synthetic paper labels.
•  Auxiliary clue: Clean, stable release from liner; crisp peeling sound at room temperature.
2. Solvent-Based Adhesive (Oil Glue)
•  Appearance: Highly transparent, varnish-like with strong gloss.
•  Feel: Slightly oily, "harder" tackiness; short, fine adhesive strings when pressing and lifting fingertip.
•  Smell: Slight solvent/chemical odor when peeled (mild for eco-friendly versions; pungent for low-quality ones).
•  Common substrates: PE/PET/BOPP film labels, outdoor labels, pipe labels.
3. Hot Melt Adhesive
•  Appearance: Thick, matte, heavily fogged surface; whitest appearance of all types.
•  Feel: Extremely aggressive initial tack; firmly grips on finger press. Hard and brittle in cold environments.
•  Key trait: Slight powdering/chipping when peeled; tack noticeably weakens when warmed (hold in palm for a few seconds).
•  Common uses: Supermarket price tags, logistics labels, rough carton labels.
4. Removable Adhesive (Repositionable)
•  Appearance: Similar to water-based—semi-transparent/milky.
•  Feel: Noticeably weaker tack; easy to peel after finger press, doesn't lock on.
•  Core characteristic: Peels cleanly off glass, plastic, metal by hand—zero residue. Permanent adhesives usually leave residue.
5. Silicone Adhesive (Niche/Premium)
•  Appearance: Highly transparent, fine, smooth layer.
•  Feel: Very weak tack, smooth, not as sticky as standard adhesives.
•  Typical uses: High-temperature labels, PI polyimide labels, labels for silicone surfaces.

II. Simple Practical Tests (Home/Workshop, Higher Accuracy)
Test 1: Water Test (Distinguishes water-based / solvent-based / hot melt)
Apply label to plastic sheet, drip water on edge:
•  Water-based: Rapidly loses tack, edges curl and lift; tack doesn't fully recover after drying.
•  Solvent-based: Virtually unaffected, remains firmly bonded.
•  Hot melt: Minimal short-term effect; slowly releases with prolonged soaking.
Test 2: Heat Test (Identifies hot melt vs. others)
Blow warm air with hair dryer on low / hold palm over label for 10–20 seconds:
•  Hot melt: Tack drops significantly, peels off easily.
•  Water-based / solvent-based / removable: Minimal tack change within normal temperature range.
Test 3: Peel Residue Test (Distinguishes permanent vs. removable)
Stick to smooth glass/acrylic, wait 5 minutes, peel:
•  Removable: Clean surface, zero residue, can be reapplied.
•  Permanent (water-based / solvent-based / hot melt): Leaves adhesive residue.
Test 4: String Test (Distinguishes solvent-based vs. water-based)
Fold label adhesive-to-adhesive, pull apart quickly:
•  Solvent-based: Continuous fine adhesive strings.
•  Water-based: Essentially no stringing, or only very short broken strands.

•  Hot melt: Thick, short strings, easy to break, sheds adhesive debris.

III. Quick Reference Mnemonics (Easy to Remember On-Site)

Observation	Conclusion
Matte surface, dry feel, curls when wet	→ Water-based
Highly glossy, oily, solvent smell, strings, water-resistant	→ Solvent-based
Whitish-matte, aggressive tack, weakens with heat, powders when peeled	→ Hot melt
Weak tack, clean peel, no residue	→ Removable
Smooth, low tack, high-temp / silicone surface use	→ Silicone