Resin Terms and Definitions

Resin Terms and Definition

This is the common language spoken when working with resin. I have added the terms and definition to give you an insight of their meaning and function.  Any question you may have feel free to leave a comment on my blog or FB page >>> http://www.facebook.com/victorian.fairys

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Accelerator: An additive to speed up the chemical reaction between the catalyst and resin or silicone.

Air-Bubble Void: Air entrapment that has occurred either on the surface or within mold rubber or casting.

Air Vent: A small hole designed as part of the master, to prevent entrapment of air when casting.

Bezel: A jewelry finding that has a rim which encompasses and fastens a jewel, watch crystal, lens or other object in a jewelry setting. Also referred to as cups.

Casting (process): Replication process by which a liquid material is usually poured into a mold, which contains a hollow cavity of a desired shape, and then allowed to solidify.

Casting (object): Cured hard copy, replica, produced by casting liquid material in silicone or plastic mold.

Catalyst: The catalyst is what causes silicone or resin to cure or harden.

Cavity: Depression in a mold; the space inside a mold wherein a casting medium is poured.

Color casting: Resin casting using material mixed with a color pigment in order to receive castings which are colored instantly.

Curing Agent: A catalytic or reactive agent which when added to a resin causes polymerization; synonymous with hardener.

Cure Inhibition: Cure inhibition occurs when a surface contaminate prevents a mold rubber from curing as expected.

Curing Temperature:  Optimal temperature for curing.

Cure Time: How long it takes for resin or silicone to fully set or cure.

Demolding: The process of removing a mold from a model or a casting from a mold; by mechanical means, by hand or by the use of compressed air.

Drying Mat: A non-stick resin drying mat used when pouring fresh resin over cured casting or while curing castings are drying.

Embedding: To encapsulate in resin or other casting material.

Epoxy: Form of liquid plastic that cures when mixed with a hardener.  Epoxy is one of the veterans in the resin family. Epoxy can also be formulated as glue.

Exotherm: The creation of heat during the curing of a plastic resin.

Extenders: Low cost materials used to dilute or extend high cost resins without much lessening of properties.

Filler: An inert material that is added to a plastic resin mixture to reduce cost, modify mechanical properties, serve as a base for color effects, or to improve the surface texture.

Flash or Flashing: Excess material attached to a molding or cast product, caused by leakage of the material between the two surfaces of a mold. Flashing is normally removed from the casting.

Gel Stage:  The semisolid stage when resin turns from a liquid to a solid.

Gel Time: The time it takes to reach the semisolid stage when resin turns from a liquid to a solid. It will be tacky or sticky to the touch.

Hardener: A substance added to control the degree of hardness of the cured plastic.

Hydrostone:  A strong plaster for making functional finished plaster products such as lamp bases, candlestick holders, mantles, etc.

HotBox: A heated box to aid in the curing process.

Inhibition: The failure of a material to cure properly.

Injection Molding: Liquid resin that is forced into a mold while under pressure.

Keys:  A depression in one part with a matching protrusion in another part used to bring mold halves or sections into alignment when joining together so the two halves will not shift.

Liquid Latex Rubber (Mold Builder): a liquid latex mold making compound that is brushed over models to create a flexible mold for casting.

Master Model:  An exact duplicate of a model, used to make numerous molds. Saves the actual model from the damage during moldmaking.

Mix Ratio:  The proper proportion (either by weight or volume) of Parts A and B to be combined. By weight requires the use of an accurate scale. By volume requires the use of measuring containers.

Model:  Your original object or pattern. Models can be anything made of wood, plastic, wax, clay, metal, plaster, bone, rock, etc. A model can be any shape, pattern, or texture you want to reproduce.

Mold Release:  A spray, liquid or powder applied in a thin film to the surface of either an original model prior to applying mold rubber, or the mold surface prior to casting.

Mold Shrinkage:  The immediate shrinkage which a casting undergoes.

Molds: A negative of the master, a form, in which castings are made by pouring into the mold a liquid material which will produce a hard copy (replicas) of the master. Molds can be made of different material depending on type of technology for which a mold is created. The most useful molds in the model making industry are silicone rubber or RTV molds, used for resin, plaster, candy, candle, and soap casting.

MSDS:  Also Material Safety Data Sheet; listing all hazards associated with the material and all safety precautions that should be taken when working with the material listed on the sheet.

Open Time or Pot Life: The amount of time you have to work with the material to get Part's A & B mixed thoroughly and applied before it gels.

Oxygen Blocker: Used to help conserve resin from damage by blocking oxygen and moisture.

Parting Line:  A mark on a master where the sections of the mold will meet.

Plaster:  A white powder consisting mostly of gypsum. You mix plaster powder with water to make a thick liquid. You can then pour the liquid plaster into a mold to make a cast product. The plaster cures to make a rigid white casting.

PSI:  - Pounds per square inch.

Polyester resin: Resin that has been around for a long time and is the resin that most people think. Cures with addition of a catalyst. Bad odor.

Polyethylene: A firm plastic that has natural chemical release qualities that make it perfect for resin casting.

Polymer Clay:  A sculptable material based on the polymer polyvinyl chloride (PVC).

Polymer: Long-chain molecules of plastic which are easily shaped and will not break when flexed.

Polypropylene:  A flexible plastic that has natural chemical release qualities that make if perfect for resin casting.

Polyurethane resin: Another form of resin that needs degassing and sets up quickly.

Pot life: The amount of time you have to work with the material to get Part's A & B mixed thoroughly and applied before it gels.

Pressure Pot:  The chamber used for Pressure casting.

Pressure Casting: Pressure casting most commonly refers to a process of putting a casting in  a pressure chamber attached to an air compressor which shrinks bubbles so small that they cannot be seen by the naked eye. It is the best method for ensuring that castings appear bubble free.

Resin: A common term, defining a family of liquid plastics used for casting in molds, creating fiberglass and some formulations are glue. Resins include mostly urethanes, epoxy and polyester.

Resin or Silicone Measuring Cups: Polypropylene cups with graduated markings for easy measuring.

Resin Colorant: A colorant mixed with resin to create a desired color.

 Liquid Pigment: is usually opaque. 

Liquid Resin Dye: Liquid colorant to mix with resin to create desired color. Dye is usually transparent.  

Room Temperature Curing:  Materials that will cure at temperatures from 68° to 86° F and later reach full strength without heating.

Rotational Cast:  Referred to as spin-casting or slush-casting; rotational casting is the process where a small amount of casting material is poured into a mold. The mold is then either rotationally spun by hand or machine to coat the entire surface of the mold. This process is continued until the casting material has begun to gel leaving a hollow cavity that may be filled with a lower cost material.

RTV (RTV silicone or silicone rubber): RTV stands for "Room Temperature Vulcanizing" and refers to a rubber material that cures completely at room temperature. This type of rubber is the most common for making poured molds. After you mix the rubber and pour it over your model, it sets up at room temperature, without needing any sort of heat treatment. 

Rubber to Rubber Mold Release: Prevents silicone rubber from adhering to previously cured silicone rubber when making multiple piece molds.

SCR: Stands for SuperClear resin.

Sealer or Sealing Agent: A quick safe and economical coating, glue, sealer, or quick decoupage.  Models that are porous like wood, ceramic, concrete, etc. or those that contain sulfur or water need to be sealed so that the rubber mold does not adhere to it.

Shelf Life:  The period of time a liquid rubber or liquid plastic can be stored and remain suitable for use.

Shore Hardness: A measurement of the hardness of different materials.

Shore A00 Scale measures rubbers and gels that are very soft like a gummy candy.

Shore A Hardness Scale measures the hardness of flexible mold rubbers that range in hardness from very soft and flexible like a rubberband, to medium and somewhat flexible like an eraser, to hard with almost no flexibility at all like a car tire.. Semi-rigid plastics can also be measured on the high end of the Shore A Scale.

Shore D Hardness Scale measures the hardness of hard rubbers like a shoe heel, semi-rigid plastics and hard plastics like a hard hat..

Silicone: A rubbery type material that usually has resistance to temperature, water, and chemicals, making it ideal for mold making.

Silicone Putty:   Silicone compounds that can be kneaded together by hand.Ideal for a wide range of impression type mold applications for Casting Resin and Epoxy, wax, baking, chocolates, ice cubes, soap, plaster, air dry clay, concrete and low melt metals. A great product for making quick molds or for replicating part of an item that cannot fit in a mold box.    

StirStix: Moisture free and reusable plastic stirrers for resin crafting. 

Tensile Properties: Ultimate Tensile Strength is the force, measured in PSI, needed to stretch a material until it breaks.

Tensile strength: Tensile strength measures the stress required to pull something to the point where it breaks.

Toobies: Small tubes for embedding in resin pieces to create holes without drilling. 

Undercut: Any indentation or protrusion in a shape that will prevent its withdrawal from a one-piece mold.

UV Resin: A one part resin that requires UV or sunlight to cure. 

Viscosity: A material, like water, with a low viscosity will flow easily.  A material, like peanut butter, with a high viscosity will not flow easily.