**UNDER CONSTRUCTION**: rewrite CA part \\
====== Requirements ======
Medical precautions: RTFM = read the instruction manual and data sheets. Wear gloves where applicable and ventilate! \\
Always de-grease your surfaces at least with detergent, better use [[life_hacks:fluids|brake cleaner]]. \\
Consider roughening your surface with sand paper. \\
====== Super glue (CA) ======
**10-second fix** or **cyanoacrylate (CA) adhesive**.
**tldr;(super glue)** \\
Super glue is commonly based on cyanoacrylate, reacting with moisture, which polymerizes the glue.
Technically it cannot be melted – heating the glue results in destruction of the polymer.
You could use an iron with blotting paper to try removing glue even out of cloth.
These glues have a softening point around ~125–165 °C. \\
CA reacts with moisture, so washing it off is impossible. \\
Try combining CA with baking soda for a hard and strong bond. \\
===== Super Glue: Composition, Behavior, and Applications =====
Super glue, known chemically as a **cyanoacrylate adhesive**, is a fast-acting, strong-bonding adhesive widely used in household, industrial, medical and aerospace contexts.
Its active ingredient is typically an **alkyl cyanoacrylate monomer**—most commonly:
* **Ethyl cyanoacrylate (ECA)** in consumer products
* **Methyl cyanoacrylate (MCA)** in some industrial applications
These monomers polymerize rapidly in the presence of even **trace amounts of moisture**, such as water vapor in the air or on surfaces.
This reaction forms strong thermosetting polymer chains that bond materials like:
* Metal
* Plastic
* Ceramic
* Rubber (non-flexible only)
The curing reaction is **exothermic**, and in some cases—especially on materials rich in **hydroxyl groups** like cotton or wool—can result in a **violent reaction** that generates enough heat to cause **burns or even spontaneous ignition**.
This occurs due to the extremely fast polymerization triggered by the hydroxyl groups in natural fibers.
There are even **accelerator sprays** that force curing to occur **instantly**.
===== Heat Resistance and Decomposition =====
Cyanoacrylate adhesives do not melt under heat. Instead, when exposed to high temperatures, they **decompose**:
* For **ethyl cyanoacrylate**, thermal degradation typically begins around **150 °C (302 °F)**
* **Methyl cyanoacrylate** may start degrading slightly earlier, in the **130–150 °C** range
* The **glass transition temperature (Tg)**—when the polymer begins to soften—is typically between **105 °C and 125 °C**
These are not softening or melting points in the traditional sense; cured cyanoacrylate does not melt but **chemically breaks down**; heating the polymer causes depolymerization.
When this happens, **irritating and potentially toxic fumes** are released, including:
* **Formaldehyde**
* **Cyanoacrylate monomers**
These byproducts affect the **eyes**, **skin**, and **respiratory system**, so any thermal removal should be done with **proper ventilation or protection**. \\
===== Removal Methods =====
Despite its strength, super glue can be removed under the right conditions:
* **Acetone** (commonly found in nail polish remover) can dissolve uncured or partially cured glue
* **Commercial debonders** containing **nitromethane** are effective
* **Heat** breaks the adhesive – for example:
* Applying a **clothes iron with blotting paper** may help lift glue from fabric surfaces
However, due caution must be used when heating cured glue due to the risk of harmful fume release. \\
===== Use Cases and Limitations =====
Super glue is best suited for **non-porous surfaces** and **Rigid joints**.
The cured adhesive is **brittle**, making it **less suitable for** load-bearing joints, applications exposed to **mechanical vibration** / **flexing**. Do not put under **thermal cycling**.
The limitation of flexibility and shock resistance have been improved by **rubber-reinforced formulations**.
* Store in a **cool, dry place**, ideally keep in the **refrigerator** (sealed in an **airtight container** to prevent condensation). Once **opened**, exposure to air moisture begins **slow polymerization** inside the container.
===== other usages =====
A lesser-known aspect of cyanoacrylate adhesives is their use in **medical and veterinary** fields.
Originally developed during **World War II** for potential battlefield wound closure, later formulations such as **butyl** and **octyl cyanoacrylates** proved to be safe and flexible enough for direct skin application
Today, **medical-grade adhesives** (e.g., *Dermabond®*) are used for closing surgical incisions and treating skin wounds.
These versions are **Biodegradable**, **Less toxic** and designed to **degrade safely inside the body**.
Super glue also plays a role in **forensic science**:
* Law enforcement uses **cyanoacrylate fuming** to reveal latent fingerprints
* Vapors from the glue adhere to fingerprint residues and polymerize
* This forms a visible **white print** on surfaces like **glass** or **plastic**
Fun fact: Super glue was famously used on NASA space missions to make emergency equipment repairs in microgravity.
===== Combine with Baking Soda =====
Combining cyanoacrylate glue with **baking soda** (*sodium bicarbonate, NaHCO₃*) results in a **very fast polymerization reaction** - ideal for DIY. To fix cracks in plastic, first roughen smooth surfaces by sanding to improve adhesion. \\
Also read about [[life_hacks:bakingsoda|baking soda vs baking powder in kitchen context]] \\
==== ✔️ Why Baking Soda Works ====
* Baking soda is **mildly basic (alkaline)**
* Polymerization of cyanoacrylate is **base-catalyzed**
* Sodium bicarbonate acts as a **strong accelerator**, causing the glue to cure **almost instantly**, even in thick layers
It also creates a **hard filler compound**, often used for:
* **Gap-filling** in repairs
* **Reinforcing joints**
* fixing cracks in plastic
* Making fast **DIY composite materials**
**Bonus**: The resulting cured mixture is:
* **Hard**
* **Sandable**
* **Drillable**
It is why it’s popular in DIY with model builders and even woodworkers.
Even try cutting threads carefully after having drilled a hole.
===== Baking Soda vs Baking Powder =====
**Baking soda** and **baking powder** are **not the same**!
==== ✖️ Why Baking Powder Fails to Accelerate Super Glue ====
Baking powder is a **mixture of ingredients** and behaves very differently. It contains:
* **Sodium bicarbonate** (baking soda)
* **Acidic salts** (e.g. monocalcium phosphate, sodium aluminum sulfate)
* Sometimes a **starch** to keep it dry and stable
**Why it doesn’t work:**
* The **acidic components** neutralize the **basic effect** of sodium bicarbonate
* This means it doesn’t provide the **alkaline environment** needed to accelerate polymerization
* **Acidic conditions** actually **inhibit** cyanoacrylate curing
* Additional components (like **starch**) dilute the reaction or act as **contaminants**
====== Solvent Cement ======
Solvent cement is technically not an adhesive in the traditional sense — it does not “stick” two surfaces with a separate binder. Instead, it chemically softens/dissolves the polymer surface, and the pieces fuse as the solvent evaporates. However, this applies only to thermoplastics that are soluble in the solvent used. \\
A famous example of such is Revell Plastic Glue, but it can be had cheaper and for different plastic types too. \\
Be cautious, most fumes of solvents are nasty for your lungs. All solvents listed are flammable and toxic; use in ventilated areas only with PPE (personal protective equipment: gloves, goggles, respirator). \\
**Methyl Ethyl Ketone (MEK)**
*Polystyrene (PS)
*ABS
*Sometimes PVC (in blends)
**Acetone**
*Polystyrene (PS)
*Acrylic (PMMA)
*ABS (slower effect)
**Tetrahydrofuran (THF)**
*PVC
*ABS
*Polystyrene (less commonly)
**n-Butyl Acetate**
*Polystyrene (PS)
*Some acrylics (PMMA)
**Lacquer Thinner (mixture of acetone, toluene, MEK, etc.)**
*Polystyrene (PS)
*ABS
*Acrylic (PMMA)
*Effectiveness varies by formulation
**Toluene**
*Polystyrene (PS)
*ABS
*Some acrylic blends
**Chloroform**
*Polystyrene (PS)
*Acrylic (PMMA)
*Very strong but highly toxic
**Methylene Chloride (DCM)**
*Polystyrene (PS)
*Acrylic (PMMA)
*Aggressive solvent; toxic
**Cyclohexanone**
*PVC
*ABS
*Used in commercial PVC cements
\\
**Polystyrene (PS)**: MEK, Acetone, n-Butyl Acetate, Toluene, Chloroform, DCM, THF (less common), Lacquer thinner, Ethyl acetate \\
**Acrylic (PMMA/Plexiglas)**: Acetone, n-Butyl Acetate, Chloroform, DCM, Ethyl acetate, Toluene (blends), Lacquer thinner \\
**ABS**: MEK, Acetone (slower), THF, Toluene, Cyclohexanone, Lacquer thinner \\
**PVC**: THF, Cyclohexanone, MEK (in blends), Lacquer thinner \\
**Polystyrene/Acrylic blends or multi-plastics**: Toluene/acetone mixtures – slower, used when aggressive solvents may distort small parts \\
\\
Hardware stores in many countries have //MEK// (Methyl Ethyl Ketone). You can also use //lacquer thinner// (varies with composition). //Acetone// will dissolve styrene and acrylic (like Plexiglas) too. \\
Better __not use__ chloroform, methylene chloride, toluene: They work well but are toxic and/or highly volatile, so stick with safer solvents like MEK, acetone, or THF. \\
Read this [[https://forum.mrhmag.com/post/gluing-styrene-because-not-everybody-knows-12199669]] and/or [[https://www.youtube.com/watch?v=VnyNbkoc72k|watch this on YT]]. \\
Note: **Solvent cement is ineffective on thermosets** (e.g. epoxy, polyurethane, phenolics etc). Compatibility generally follows polymer solubility parameters: the solvent must have a similar Hildebrand or Hansen solubility parameter to the target plastic. \\
====== UV glue ======
UV glue is a type of adhesive that cures when exposed to ultraviolet light. It remains liquid until activated by UV radiation, allowing precise positioning and clean application.
Typically composed of acrylate or methacrylate monomers and oligomers, along with photoinitiators. When exposed to UV light, the photoinitiators generate free radicals that rapidly polymerize the monomers into a solid plastic-like material forming a a strong, clear bond within seconds.
UV glue is ideal for glass, plastics, and electronics, and is commonly used in optical and jewelry work due to its transparency and fast curing.
====== Hot glue ======
Hot glue is often used in hot glue guns with different temperatures. There are all kinds of different sticks with different temps for different materials. \\
(EVA thermoplastic)
- consider ski repair sticks as hot glue \\
- you can even burn thermoplastics with a lighter (e.g. zip ties) and let use the melted plastic: be aware that it gets brittle \\
====== 2-components ======
===== Epoxy =====
Two-component epoxy consists of a resin and a hardener that must be mixed before use. The chemical reaction between the two forms a very strong, durable bond resistant to heat, chemicals, and moisture. Epoxies are versatile and suitable for bonding metal, wood, plastic, and ceramics. Depending on the formulation, curing time can range from minutes to hours, allowing both quick fixes and structural applications.
Epoxy resin is often based on bisphenol-A diglycidyl ether and its hardener is commonly a polyamine or anhydride. Mixing triggers a chemical reaction—usually a step-growth polymerization—forming a strong, crosslinked thermoset polymer.
Epoxy is toxic in its uncured (liquid) state. Once fully cured, it is generally inert and stable, but not all epoxies are food-safe. Most epoxies start releasing toxic fumes when heated to temperatures around 120°C to 150°C (248°F to 302°F). Softening starts often already around 65°C (149°F). Significant deterioration around 120°C (248°F) affecting the adhesive bond and structural integrity. \\
===== Play-dough =====
#TODO: missing \\
====== Other ======
* Think outside the box: Ski repair sticks are good for filling cracks/holes of plastics too. Just make sure you tape non-melting and non-flammable material on the other side, so the plastics will not deform! \\
* flaming thermoplastics (e.g. zip ties) with a lighter for plastics repair (it gets brittle though) \\
* There is glue for nearly every material with different compositions:
* Vulcanizing glue for rubber: Commonly used on bicycle tires. Roughen the surface with sandpaper first
* ceramics, aka elephant glue
* wood glue (PVA / aliphatic resin) – hard, rigid joint
* fabric / textile adhesive (sticks to wood too but remains highly flexible)
* contact cement aka "Pattex" (stays flexible): There is a solvent-free version too which needs pressure to fixate.
* Silicone adhesive / sealant can be used as flexible glue and is waterproof
* Latex-based glue – very flexible, used for fabrics and paper crafts
* PU (polyurethane) glue – flexible to semi-rigid, gap-filling, moisture-curing; often used in mounting adhesive
* Rubber cement – flexible, peelable
* Acrylic polymer emulsions (PVA-like but stronger, more weather-resistant); can be painted over
Fun Facts:
* Regular Pattex glue will "melt" through styrofoam (expandable polystyrene foam (EPS)) and deform polystyrene (PS) as it contains [[life_hacks:glue#solvent_cement|solvents]] \\
* Post-it glue was originally developed for super strong adhesive but was discovered by accident and remained unused until the invention of the sticky note. \\