Glue

Glue is used during manufacturing to adhere the puzzle image to the board, and it is also used by puzzlers to repair puzzle pieces and to seal a puzzle for hanging or framing.

Glue Used By Manufacturers

When a puzzle image is adhered to the puzzle board during manufacturing, specific types of glue are used to ensure a strong, durable, and smooth bond. The goal is to prevent warping, bubbling, or peeling of the image from the cardboard or wood backing. There isn’t a one-size-fits-all solution for glue when it comes to puzzle manufacturers. Selecting a suitable adhesive for your application depends on the equipment, production speed, and type of board and paper used. Many manufacturers use a variant of gelatin glue or, in some cases, liquid glue due to their fast drying times. Discolored or warped puzzle pieces can cause many issues for end-users; no one wants to assemble a bent puzzle that does not easily snap together.

When choosing an adhesive for puzzle-making, manufacturers consider such things as:

• Does the glue dry clear?

• Does the glue dry quickly?

• Will the adhesive bleed through the puzzle pieces?

• When the glue dries, does it warp the board?

Types of Glue

• • Gelatin Glue (Protein Glue): This is a prevalent choice in large-scale puzzle production. It's favored for being non-toxic, biodegradable, and derived from recyclable sources.

  • Liquid White Glues (e.g., PVA-based): These are also commonly used, especially for manufacturing jigsaw puzzles and for the puzzle boxes themselves. They are non-toxic and offer good adhesion. Water-based adhesives (dispersion adhesives) are popular due to being eco-friendly, non-toxic, easy to recycle, and safe to handle.

Key Considerations Used In Glue Selection

• • Drying Time: Manufacturers often use quick-drying adhesives to prevent blade dulling during die-cutting and to avoid deformation of pieces.

  • Adherence Properties: The glue needs to be strong enough to withstand the cutting process and repeated assembly. "Good fiber tearing" indicates excellent adhesion, where the paper fibers tear before the glue bond breaks.

  • Application Precision: Too much glue can damage pieces or cause the board to warp. Manufacturers use specialized equipment to measure and apply optimal adhesive thickness.

  • Material Compatibility: The adhesive must be carefully selected to work with the specific types of paper (lithographic prints) and puzzle board (cardboard, wood) being used.

Glues used by Puzzlers

To repair broken pieces

• Elmer's Wood Glue or PVA glue

• Craft glue

To Repair Separating Layers

• Mod Podge

• Elmer's White School Glue

To Glue the Entire Puzzle for Display

• Liquid Puzzle Glues

  • Composition: Often water-soluble formulas, commonly PVA-based, designed to dry clear and provide a permanent bond.

  • Application: Applied directly to the top (image side) of the puzzle with a brush, sponge applicator, or spreader. It's crucial to get even coverage, working the glue into the seams between pieces.

  • Benefits: Strong hold, often dries with a glossy or matte finish depending on the product, allows the artwork to shine through.

  • Considerations: Can be messy, requires careful spreading to avoid streaks or pooling, and can potentially cause slight warping if applied too heavily. Brands like Mod Podge, MasterPieces, Ravensburger, and SunsOut offer these.

• Mod Podge: A popular multi-purpose crafting adhesive, sealer, and finish. It's highly recommended by puzzlers for its versatility, clear drying, and durable finish (available in glossy or matte). It can be used as a glue to hold the pieces together and as a protective topcoat.

• Peel-and-Stick Adhesive Sheets

  • Description: These are pre-cut adhesive sheets that you apply to the back of the completed puzzle.

  • Application: The puzzle is flipped over, and the adhesive sheets are peeled and stuck to the back, often overlapping to cover the entire area.

  • Benefits: Mess-free, quick, no drying time on the front, and often come with hangers for display.

  • Considerations: Requires careful flipping of the puzzle, and may be thinner or harder to work with than liquid glues, depending on the brand.

• Spray Adhesive

  • Application: Sprayed over the completed puzzle, typically on the back for mounting to a board.

  • Benefits: Quick and easy for large puzzles, can save time.

  • Considerations: May not provide as strong a bond as liquid glues, can be harsh and smelly (requiring good ventilation and a mask), and may need a backing layer for added strength.

Final Thoughts

While manufacturing processes utilize specialized industrial adhesives like gelatin or high-performance water-based glues for mass production, hobbyists have a range of liquid glues or convenient peel-and-stick sheets to preserve their finished puzzles.