In the wonderful world of glue, there are a lot of terms and phrases thrown around that may not be familiar.
This glue glossary will help to define many of those "sticky" glue terms.
Centipoise: A viscosity measurement unit. A centipoise is one hundredth of a poise.
Compression Time: The length of time that pressure is applied to the glued substrates.
End Use Requirements: This details the needs that the finished (glued) product must fill Ex.: freezer grade, withstand high heat or humidity
Gelatin: Gelatin is a protein derived by from a parent protein, collagen. It is almost tasteless, odorless, vitreous, brittle solid and usually faintly yellow in color. Gelatin is graded according to its strength, called its ‘bloom’. The higher the bloom numbers, the higher the grade.
Gram Strength: The gram strength of a material is important in our industry because it correlates to the rigidity of the glue after the bond has been formed. The higher the gram strength, the stronger the cohesive forces in the glue.
Mil Depth: A measurement, in MIL's (0.001"), of glue applied to a substrate. This is measured with a mil depth gauge.
Open Time: Is the elapsed time between the moment the glue is applied onto the material, and the time the glue has lost its bonding power.
Optimal Running Temperature: The temperature at which the glue runs most favorably. This information can be found on the product data sheet and will vary depending on the type of glue.
pH: The measure of acidity or basicity of the glue formula.
Running dirty: This is a term used when the glue clogs equipment nozzles or begins to build up on the equipment picks.
Score: Cuts made in glue cakes which make them easier to pull apart.
Shear Time: Is the elapsed time between the moment the materials are pressed together and the moment they can no longer be separated without tearing fibres.
"Slip on the roll": When the glue runs clean on the rolls and picks of the equipment.
Solids: The percentage of solids versus water in the glue formula. This can be measured with a refractometer.
Speed: Referring to gluing equipment speeds. Typically provided in terms of boxes per minute (BPM) or cases per minute (CPM).
Stringing: This happens when a hot melt glue runs cold and begins to "string" at the nozzles. When this happens, it resembles spider webs.
Substrate: The material(s) to be glued.
Tack: The level of "stickiness" in the glue.
Tack range/development: The length of time that the glue stays tacky before it sets.
Temperature: The degree of heat in the glue at application.
Viscosity: The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For glues, it corresponds to the concept of glue thickness.