Glues and adhesives are substances used to join objects together. From crafting to construction, glues play an essential role in bonding materials. With so many types available, choosing the right glue can be confusing.
Classification of Glues
Glues can be divided into categories based on their composition and properties:
Natural vs Synthetic Glues
Natural glues are made from organic materials like plant starch and animal collagen. Traditional natural glues include hide glue from animal skin and pine resin. They tend to be weaker than synthetic glues.
Synthetic glues are made from petroleum-derived polymers, acrylics, epoxies and other chemicals. They can be engineered to have precise properties and bond strengths. PVA, superglue and hot glue are examples of synthetic glues.
Drying Methods
Glues can also be categorized according to their drying or curing process:
- Solvent-based: The glue contains volatile solvents that evaporate, leaving the adhesive behind
- Reactive: The glue undergoes a chemical reaction, forming crosslinks between polymer chains to harden
- Thermoplastic: The glue sets upon cooling and solidifying from a melted state
- Pressure-sensitive: The glue adheres instantly under pressure without any reaction or drying
Water-Based Glues
Water-based glues use water as the solvent. They are safe, non-toxic and easy to use. However, they provide a weaker bond than other adhesives.
White Glue (PVA Glue)
Also called carpenter’s glue, Elmer’s glue or school glue. The white color comes from titanium dioxide powder added to the polyvinyl acetate (PVA).
Applications: Ideal for porous materials like paper, cardboard, wood and fabric. Widely used in schools and offices.
Properties:
- Dries transparent – good for invisible bonds
- Non-toxic and washable
- Medium bonding strength
- Long drying time – 24 hours for full cure
Tips for Use: Surfaces should be clean and free of dust. Apply thin layer of glue and clamp pieces together as it dries. Wipe away excess glue immediately with damp cloth. Store with lid tightly closed to prevent drying out.
Glue Sticks
These contain solid PVA glue in a twistable stick, which applies a thin film of adhesive. Convenient for temporary bonds.
Applications: Mainly used for papercrafts, scrapbooking and photos. The glue is acid-free and safe for delicate materials.
Properties:
- Easy twist-up application
- Dries quickly and bonds weakly – allows repositioning
- Washable and non-toxic
Tips for Use: Apply thin, even layer over entire surface. Press pieces firmly together. Keep glue stick capped when not in use.
Gel Glue
Has a thicker gel-like consistency which resists running and dripping. It can be applied to vertical surfaces.
Applications: Good for porous materials like paper, cardboard and fabric. The viscosity allows 3D bonding rather than flat surfaces only.
Properties:
- Thick consistency – won’t drip or run
- Stronger bond than liquid white glues
- Extended drying time allows repositioning
- Acid-free – safe for photos and delicate materials
Tips for Use: Ensure surfaces are clean before gluing. Apply gel in thin layers and press materials firmly together as it dries. Clamps can help hold pieces in place while drying.
Solvent-Based Glues
These adhesives use volatile solvents which evaporate after application, leaving the sticky resin behind to bond. They create very strong, permanent bonds.
Contact Adhesive
Bonds instantly and powerfully when pressed together after drying. Difficult to reverse once bonded.
Applications: Ideal for laminates, veneer, metal, rubber, plastic, tile, wood, and more. Not suitable for flexible surfaces.
Properties:
- Applies easily with brush or roller
- Forms permanent, high-strength bonds
- Allows repositioning during assembly
- Withstands high temperatures
Tips for Use: Apply adhesive evenly to both surfaces and allow to dry completely. Join pieces with firm pressure. Be precise, as the bond forms instantly.
Rubber Cement
Produces flexible, temporary bonds. Allows repositioning even after drying.
Applications: Widely used for papercrafts and scrapbooking. Also useful for flexible materials like fabrics and photos.
Properties:
- Fast drying time
- Weak bond allows repositioning
- Easy cleanup with petroleum solvents
- Versatile for many porous and flexible materials
Tips for Use: Apply thin, even coats to both surfaces. Allow to dry thoroughly before joining – test tackiness first. Reactivate with solvents like acetone for adjustments. Store tightly sealed.
Model Cement
Specialized cement for plastic model assembly. Chemically welds plastic pieces together.
Applications: Designed specifically for plastic models and miniatures. Commonly used in modeling hobbies.
Properties:
- Creates high-strength, permanent plastic welds
- Short drying time
- Unaffected by temperature changes
- Allows smoothing of seam lines
Tips for Use: Hold pieces firmly together while cement cures. Avoid excess runoff onto visible surfaces. Allow to fully cure before handling – up to 24 hours for ABS plastic.
Super Glue (Cyanoacrylate Adhesive)
Instantly bonds with extremely high strength. Temperature and moisture-resistant.
Applications: Ideal when you need an immediate, powerful bond. Works with metal, plastic, rubber, ceramic, leather and more.
Properties:
- Incredibly fast cure time – often under a minute
- Creates permanent, durable bonds
- Withstands temperatures up to 180°F
- Resists chemicals, oils, solvents and moisture
Tips for Use: Surfaces must be clean and accurately aligned before bonding. Apply just a small drop and press parts firmly together. Cures more slowly in cold temperatures.
Other Glue Types
Here are some other common adhesive types and their uses:
Hot Glue
Thermoplastic adhesive applied molten through a hot glue gun. Sets rapidly as it cools.
Applications: Fast bonds for paper, fabric, plastic, ceramics, wood and more. Useful for prototypes and temporary bonds.
Properties:
- Super fast drying time – solidifies in under a minute
- Forms semi-rigid bonds with medium-high strength
- Easy cleanup while hot – solidified glue is difficult to remove
Tips for Use: Allow glue gun to fully heat up first. Apply in thin layers while pushing surfaces together to prevent stringing. Avoid burns from hot adhesive.
Epoxy
Two-part adhesive that cures into an extremely tough, rigid bond. Resists heat, chemicals and weathering.
Applications: Permanently bonds metals, glass, stone, ceramics, plastics and more. Used extensively in construction and repair applications.
Properties:
- Creates a plastic-like bonded area
- Incredible strength – often stronger than materials being bonded
- Does not shrink or pull away as it cures
- Withstands temperatures up to 400°F when cured
Tips for Use: Carefully mix equal parts resin and hardener. Pot life is limited once mixed. Apply thin layer between parts and clamp until fully cured.
Silicone Sealant
Flexible adhesive and sealant used for weatherproofing and filling gaps. Withstands temperature extremes.
Applications: Versatile for industrial and household use. Bonds glass, metal, plastic, vinyl, porcelain, tile and more while remaining flexible. Used to seal windows, plumbing, roofing and ductwork.
Properties:
- Stays permanently flexible after curing
- Excellent adhesion to many materials
- Resists weathering, moisture and temperature extremes
- Many formulations meet food safety standards
Tips for Use: Ensure surfaces are clean and dry before application. Apply steady pressure while smoothing sealant into gap. Allow 24 hours for full cure.
Spray Adhesive
Mist spray adhesive applied from an aerosol can. Useful for large or hard-to-reach surfaces.
Applications: Temporary bonding for paper, cardboard, photos, fabrics and foam. Used in crafts and upholstery work.
Properties:
- Spray application coats large areas quickly and evenly
- Tacky adhesive is repositionable when first applied
- Allows smooth, wrinkle-free application to surfaces
- Produces relatively weak, temporary bonds
Tips for Use: Spray light, even coat on both surfaces from 6-8 inches away. Allow to partially dry then join surfaces. Ventilate area and avoid inhaling vapors.
Glue Sticks
These contain solid PVA glue in a twistable stick, which applies a thin film of adhesive. Convenient for temporary bonds.
Applications: Mainly used for papercrafts, scrapbooking and photos. The glue is acid-free and safe for delicate materials.
Properties:
- Easy twist-up application
- Dries quickly and bonds weakly – allows repositioning
- Washable and non-toxic
Tips for Use: Apply thin, even layer over entire surface. Press pieces firmly together. Keep glue stick capped when not in use.
Choosing the Right Glue
With so many glue types available, it can be tricky choosing the best one for your project. Here are some tips for selecting the right adhesive:
- Consider the materials you are bonding. Glues work better with certain materials. Cyanoacrylate works wonderfully with plastic and rubber but poorly with paper or wood.
- How strong does the bond need to be? Permanent bonds require epoxy or super glue. Temporary bonds can use hot glue or rubber cement. White glue gives medium strength.
- Will the glue be exposed to water? Glues like PVA and hot glue will weaken and fail over time when exposed to water. Use specialty adhesives like silicone or epoxy for waterproof, outdoor bonds.
- What is the drying time? Projects requiring fast bonds need quick-setting super glue or hot glue. Epoxy and PVA take hours to fully cure.
- Does it need to withstand heat? High-temperature applications call for heat-resistant epoxies, silicone or cyanoacrylate glue. Other glues lose strength when heated.
- Consider toxicity. Many common glues like PVA, hot glue and rubber cement have low toxicity, making them safe for kids’ and school projects. Others like epoxy and superglues can irritate skin and eyes.
- How precise does the application need to be? Glues like superglue bond instantly, allowing little repositioning. Slower-setting white glues allow more adjustment time.
By considering these factors, you can select the ideal glue to create strong, long-lasting bonds for any project. With a little knowledge and the right adhesive, you can glue just about anything!