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Glossary of Terms

 1st surface printing
Process of printing on the side of the label or appliqué that will not be in contact with the plastic substrate. This type of printing will result in graphics that are less durable

 2nd surface printing
Process of printing on the side of the label or appliqué that will be in contact with the plastic substrate. This type of printing will result in graphics that are more durable.

A process where a printed and formed sheet of film is placed in the cavity or core side of an injection mold and plastic is injected behind it.

 3-Plate runner
A system used in injection molding where the runner is formed on a separate parting line behind the cavity plate. This enables you to locate the gates, on the top of the part, away from the main parting line. This method, used in conjunction with pin gates can be useful to direct the plastic flow behind the IMD appliqué.


Activation  Temperature

The temperature at which a heat seal coating becomes tacky.


 Label or mold insert, either flat or pre-formed, which is placed in the mold and fuses to the part during the molding process; the in-mold label or in-mold decoration.


 Banana gate

 Also called a “cashew” gate, it is used in injection molding where automatic de-gating (no trimming) is required on a surface near parallel to the parting line of the mold. The resin is channeled through a curved tunnel similar in shape to a banana half or cashew. This gate leaves little gate remnant. This method can be useful to direct the plastic flow behind the IMD appliqué.

 Basis weight

 The weight of a known area of the substrate, usually in pounds/ream or grams/sq.  meter.


 Printing or decoration defect on the appliqué, where edges are not uniform and the ink appears to bleed into an adjacent area.


 A form of delamination is a void or pocket that appears as a bulge on the surface of the appliqué after injection molding. It is often caused by the pressure of gasses created in the injection molding process.


 The tendency of two plies of the substrate to stick together in a stack or roll, especially under heat and/or pressure.

 Blow Pin

 A hollow device, inserted into the hot parison after mold closing, through which high-pressure air expands the parison.


 Manufacturer of plastic bottles used for food and household chemicals.

 Bond strength

 The force required to separate two surfaces that have been laminated or heat-sealed together.


 Biaxially oriented polypropylene. The film is stretched in both the machine direction and cross-machine direction to increase its strength.


 Accumulation of ink material that is viewed as a bulge or protrusion on the appliqué.


 Label defect similar in shape to a blister where the label is not firmly adhered to the container.


Two (2) side coated substrate.

Substrate thickness expressed in mils or points (1 mil = 0.001 inch) or microns (1 mil = 25.4microns).

Cast film
Polyolefin film, usually polypropylene, which is not oriented after it is extruded.

Cavitated film
A co-extruded film consisting of a partially foamed or “cavitated” inner core layer and thin solid outer layers. This sandwich is much stronger, has better stiffness and has a higher yield than a solid mono-layer film of the same caliper.

Clamping station
Mold cavity on a wheel or shuttle blow molding machine.

A very mild form of blocking where the plies can be easily separated without visible damage to either surface.

Accumulation of small bubbles on the surface of the appliqué created during the printing operation.

Simultaneous extrusion of two or more molten polymers to form a multi-layer parison.

(See “Slip.”) The coefficient of friction is the ratio of the frictional force to the force acting perpendicular to the direction of motion.

Static COF
The ratio of the force needed to start the motion between two surfaces in contact to the force acting perpendicular to the direction of motion.

Kinetic COF
The ratio of the force needed to sustain the motion between two surfaces in contact to the force acting perpendicular to the direction of motion.

Cold slug
The leading portion of the melt flow in injection molding that has been cooled below the effective molding temperature of the resin. It usually appears as a flaw on the surface of the molded part.

Foreign matter or material embedded in the surface of the appliqué during the printing process.

A manufacturer who produces value added products from single web materials by laminating, coating and/or printing operations.

Counter pressure high die
Pressure applied against the square cut label stack during the high die-cutting process to
improve print-to-cut accuracy.

The ability to easily remove part of a label for point-of-purchase redemption.

Splitting or fissures causing separation of the appliqué. Caused by improper packaging or dents on the appliqué edge.

Label defect which looks like alligator skin. Also, multiple tiny cracks due to stress exerted on a 3D appliqué during the forming operation.

A label edge or corner that does not lay flat on a plane surface.

Cut in place (CIP)
A device at the molding site that cuts labels from a web and place them directly in a mold.

Cycle time penalty
Time added to IML production cycle due to label
insertion or part cool down.


When the appliqué or label does not adhere to the plastic substrate to any degree.

Removal of bottles from cartons.

Die cut
Labels cut from printed sheets or web using a sharp device similar to a “cookie cutter.”

 Die cut punch
Cut on the appliqué out of registration, that is created in the die cut process.

Digital printing
Imaging sent directly from computer to printer 

Dimensional stability
The ability of a film to resist stretching or shrinking during converting or blow molding.

Color shifts on the printing or decoration on the appliqué.

Dot gain 
Spreading of a printed dot resulting in a loss of image definition or sharpness.

Double picking  
Two or more labels that stuck together when fed from a magazine stack. 


Edge welding
Labels whose edges are fused together during die cutting.

Ethylene vinyl acetate, a polymer used in heat activated adhesives

Ethylene vinyl alcohol, a polymer used for the gas barriers in laminations.

A machine that melts plastic resin pellets into a molten mass used to form a parison or injected into a mold.

Continuous conversion of resin pellets into a molten sheet, ribbon or tube for further processing.


Uneven trim edge where the ink protrudes as feathers. This happens when the die  has chipped off feather edges of the ink during the die cutting operation.

Film in-mold labeling.

Label defect where edges are lifted from the container.

Flame Treat
Surface oxidation is required for the adhesion of labels.

Excess plastic that is trimmed off of the part after the part is ejected from the mold.

Flatbed die cutting
Sharpened blades mounted on flat support which cuts the label from the surrounding matrix.

Printing process using polymeric plates with raised images and fluid inks.

Foil stamping
Colored metallic foil transferred to the label surface with heat and pressure.

Forming dent
Deformation on the appliqué that is created in the forming process.

Form register defect
Forming a shape that is off registered with the printing or decoration.

The force that resists relative motion between two surfaces in contact.


Gang filling
Batch dispensing of product into a group of containers using multiple filling heads.  See in-case filling.

The orifice through which resin flows from the runner to the part. This orifice could take various forms depending on the part design requirements.

Gel lacquer
A solvent solution of a hot melt heat seal coating applied by heated gravure.

Graphic streak
Line shaped color changes on the Appliqué that vary in length and width.

Gravure (roto)
Printing method which transfers ink or coating to a substrate from tiny cells etched in a metal cylinder.


Health and beauty aids.

High density polyethylene

Heat resistance
Temperature to which a bond or seal can be raised before it fails.

Heat transfer
Decal-like label that is transferred by heat and pressure from a release coated carrier web onto a container or molded object.

Heat seal coating
Adhesive coating that is non-tacky at room temperature but becomes sticky when heated.

HIC containers 
Containers for household and industrial chemicals.

High die cutting
Off-line process for punching out labels from a stack of 500 to 1,000 label sheets in  a single stroke using a hollow cutting tool.

Hot runner manifold
A system used in injection molding where the runner is kept above the melting temperature at all times. This avoids runner waste and enables you to locate the  gates on the top of the part, away from the main parting line. This method, used in conjunction with pin gates can be useful to direct the plastic flow behind the IMD  appliqué.

Hot tack
Strength of a still-molten bond immediately after pressure is released.

An ambient temperature, high pressure forming method in which a plastic sheet is placed between a forming tool and a flexible urethane “bladder”. Hydraulic pressure is applied to the bladder to force the plastic sheet to conform to the forming tool.


In-mold decorating.

IML-B (See Blowmolding and/or Extrusion)

IML-I (See Injection IML.)
Injection mold in-mold labeling.

In-mold labeling, usually of containers.

IML foot
The ledge is placed at the bottom of a container mold to help capture the label when using a wrap-around label. This prevents plastic from going to the front side of the label.

IML-T (See Thermoform IML)

In-case filling
Gang filling of bottles without removing them from the carton or case.

Injection IML
Method where die cut label and a forming core are placed in a mold. Molten plastic is injected into the inner space between the backside of the label and the forming core.

Injection stretch blow molding (ISBM)
Blow molding method where a parison preform is made, then reheated, stretched and blown to the bottle shape.

Ink wash
An area on an IMD decorated part where the ink has been moved around or destroyed by heat, friction or pressure from the injection molding process. Sometimes called ink blowout.

ISBM (See Injection Stretch Blow Molding.)


Knit lines
Flaws in the surface of a plastic part are caused by the meeting of two or more flow fronts during molding. These flaws can range from lines to deep crevices.


An imaging technique using parallel “corrugated” lenses applied over an image to impart a visual effect of depth and motion.

A printing process that transfers ink from raised image areas on metal or polymeric plates.

Fabric debris entrapped on appliqué during the printing process.

Litho (See Offset lithography)


The part that transfers label to the female side of mold.

Match metal die
A more expensive die is used for cutting 3D appliqués. This die is constructed from hardened tool steel and the punch and die are precision matched to form the cutting edge. This type of die is useful where the cut is not on a planer surface or where you need to cut on the side of a 3D appliqué.

Machine direction orientation. The axis of orientation of a film parallel to the direction of the forming web movement.

Mold release
Additive in a plastic resin that prevents molded container or part from sticking to the mold.

Thousand square inches are commonly used measure for label pricing.

Municipal solid waste.

Multi-shot molding
A process where two or more injection processes take place during the cycle. This could be multiple colors, clear and opaque, hard and soft, dissimilar materials or the same material shot at different times. Normally if the materials are dissimilar, special “over-molding” grades are used.


Narrow web
Press that uses a maximum web width of 18 to 24 inches.


Offset lithography
A printing method in which a grease-like ink is transferred or “offset” from the image to a rubber “blanket” cylinder and then to either a web or sheet of substrate.

Rejected blow molded or injection molded containers.

Oriented polypropylene, usually biaxial.

Orange peel
Textured or micro-pitted label surface appearance resembling the surface of an orange. Usually caused by partial collapse of the cavitated film core during molding.

Overprint lacquer
Clear varnish or coating is applied over a printed surface to protect it.


How in-mold labels are packaged for shipment to molders for usage.

Panel bulge
The outward bulge of the labeled side of an in-mold labeled bottle, common to paper labels and
some plastic labels.

A tube of molten plastic extended from the extruder that is captured by the closing mold.

Parison “touch down”
Premature contact of parison with the back of label during the blow molding cycle.

Post consumer resin.

Polyethylene terephthalate (polyester).

Pick and place
An articulated robotic device that picks up a label from the magazine stack and positions it in the
open mold.

Pin gate
Used in injection molding in conjunction with a hot runner manifold or a 3-plate runner system. This gate is automatic de-gating (no trimming) and leaves a small remnant in the shape of a pin mark

Pinning device
Mechanism for holding an in-mold label against the interior wall of a mold until the resin is introduced into the closed mold.

Crater-like imperfections on the surface of the appliqué after injection molding. These are caused by foreign matter between the appliqué and the cavity when injecting resin.

A low molecular weight polymer additive used to soften or make pliable and otherwise hard or brittle plastic.


Labeling of packaging before filling with the product, usually at molder.

Label defect where the label edge is lifted away from the container.


Reciprocating flatbed
Roll fed die cutting process where the web stops to allow die head to cut a single label from the web.

Offware that is granulated and fed back into
the extruder.

Release liner
Paper or film carrier for heat transfer or pressure sensitive labels.

Retained solvents
Solvent or water trapped in a coating, adhesive or ink.

Deformation and flow properties of polymers.

Ridge or wrinkle shaped label defect.

Rotary die cutting
Offpress process of punching out individual labels using sharpened rules mounted in a support bed.

Rotary machine
Blow molding machine that has blowing stations mounted on a vertical or horizontal wheel.

Rotary screen
A printing method where ink is forced through a screen cylinder by a doctor blade inside the cylinder.

The printing method that transfers ink or coating to a substrate from tiny cells etched in a metal cylinder.

The channel in the mold body through which the resin flows to the part.


Scrap (See “Offware.”)

Surface imperfection due to abrasion that removes small amounts of appliqué material.

A square or rectangular container with rounded corners.

Set-off powder
The starch-based powder used at end of sheet-fed offset press to prevent face-to-back transfer
of wet ink in stacked sheets.

Sheet offset (See Offset lithography)

Shuttle machine
Blow molding machine that has blowing stations on either side of a central extruder. Mold shuttles between extruder and blow station.

Sink marks
Depressions on the surface of a molded part caused by a low-pressure situation in the injection molding process. This can be caused by under-packing of the part due to process or by achieving gate seal prior to a thick section being solidified.

Slip (See “COF.”)
Term used in the opposite sense of COF. A high slip normally refers to low COF and a low slip
refers to high COF.

Dot shaped marks on the appliqué are caused by ink or foreign material during the printing process.

The part of the runner formed by the resin flowing through the sprue bushing, a feature of the mold that interfaces with the injection machine nozzle.

Sprue gate
Where the part is filled directly from the sprue bushing of the injection mold. This leaves a large “carrot” looking gate remnant that must be trimmed.

Steel rule die
A less expensive die used for cutting the appliqué or label. This die is manufactured by bending a steel rule cutting blade around a form such as wood. The cutting action is performed between the sharp edge of the steel rule and a flat surface of wood, plastic or metal (like a cookie cutter). This die is good for simple and flat cuts.

Stress mark
A white or gold colored defect that appears on the appliqué when it is formed, bent or creased.

Sub gate
Also called a “tunnel” gate, it is used in injection molding when automatic de-gating (no trimming) is required on a surface near perpendicular to the parting line of the mold. The resin is channeled through an angled, tapered tunnel, entering the part on a side wall. This gate leaves little gate remnant.

Film or paper on which a label is printed.

Sustainability in the labeling or decorating of plastic objects is the use of minimum resources to accomplish the task, including materials, energy, labor and money.


Tab gate
Gate used in injection molding that is simply a tab cut on parting line connecting the runner to the part. Post-mold trimming is necessary.

Trans-directional or cross web orientation of a polyolefin film.

TF-IML (See Thermoform IML.)

IML Method where die cut label is placed in a mold. A plastic sheet is indexed over the mold then heated and forced into the mold forming the container.

Tie layer
The extruded adhesive layer is used to bridge or bond together two otherwise incompatible polymer films.


UV flexo
Same as flexo except it uses 100% reactiveinks cured by UV radiation.


Vacuum port
Small openings in a mold that hold labels in place during blow molding.

Valve gate
A heated gate is used in injection molding to produce a remnant free part. The only thing visible is a circular impression similar to an ejector pin mark. The straight or tapered pin valve is actuated by hydraulics or pneumatics on a timer. This gate can be useful to direct the plastic flow behind the IMD appliqué and to reduce shear and ink wash on the appliqué near the gate.

Vertical insert molding
A process using an injection molding machine with a vertical clamping unit. The machine can use horizontal or vertical injection units or both. Some presses use a rotary or shuttle table for increased production. This process uses gravity to hold inserts in the mold while injecting the resin.

Resistance of a coating or ink to flow under an applied force.


The substrate to be printed or coated as it unwinds from a roll.

Web offset (See Offset lithography)

Wheel machine
Continuous extrusion blow molding machine
that has molds positioned around a large wheel.

This glossary is continuously updated by IMDA.
Suggestions for additional terms and/or definitions are welcome.
Contact IMDA with ideas and suggestions at