Common resin crafting terms

dictionary

Resin jewelry making and crafting definitions

Note:  These terms are defined as they relate to resin casting and resin jewelry making.  If you have questions or would like an additional term added to the list, please comment below.

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

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

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

Bezel: A jewelry finding that has a rim which can hold the resin. May also be 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): A cured resin piece.

Catalyst: Causes the resin to solidify.  Sold in a separate container from the resin, but usually sold in a kit with the resin.  Made to specifically match the resin with which it is intended for use.

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

Cure (process):  The reaction that occurs between resin and hardener to allow it to fully set or harden.

Cure Inhibition: When a contaminate prevents resin from curing as expected.

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

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

Curing Temperature:  Optimal temperature for curing.

Demolding: The process of removing a model or casting from a mold.

Demolding time:  Period at which the casting can be demolded.  May require more time to fully cure (cure time).

Doming:  Process of using a resin to create a resin dome on a surface.  Also refers to a resin suitable for this process.

Embedding: To encapsulate an object or other finding in resin or other casting material.

Epoxy: Class of synthetic thermosetting polymers containing epoxide groups.  One of the most widely available resins.

Exothermic: A chemical reaction that causes heat production.  A necessary reaction for resin to cure.

Findings:  Parts used to make resin castings wearable as jewelry

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.

Gel Stage:  The semisolid stage between when resin turns from a liquid to a solid.  At this point, the resin can no longer be worked with.

Gel Time: The time it takes to reach the semisolid stage. The resin will be tacky or sticky when it reaches this point.

Hardener: A substance added to resin to cause it to cure.  May also be referred to as catalyst.

Inclusions:  Anything being added to resin.  This can be colorants, found objects, art and craft items or jewelry findings.

Inhibition: The failure of the resin to cure properly.

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.

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

Mix Ratio:  The proper proportion (either by weight or volume) of resin and hardener (oftentimes referred to as Parts A and B) to be combined.

Model:  An object or pattern that serves as the template for a mold. 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 compound applied in a thin layer to the surface of an item, either a model or mold, to allow the subsequent resin casting to be demolded.

Mold Shrinkage:  The amount of size difference between a casting and its original model.

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 copy (replica) of the master. Molds can be made of different materials, but in resin crafting as most commonly made from plastic or silicone.

MSDS:  Material Safety Data Sheet.  Provides information on product components and how to work with it in a safe manner.

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Open Time: See pot time.

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

Polyester resin: Generally mixes with drops of hardener based upon the volume and thickness of the casting. Bad odor.

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

Polymer Clay
:  A sculptable material based on the polymer polyvinyl chloride (PVC).  Can be used as a model for resin casting and mold production.

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

Polyurethane: A synthetic resin that cures very hard.  Also comes in forms/kits that cure very quickly.  Moisture sensitive.  Mold making versions also available.

Pot time
:  The amount of time you have to work with the resin to get Parts A & B mixed thoroughly and applied before it gels.  May also be referred to as pot life.

Pressure Casting: Most commonly refers to a process of putting a casting in a pressure chamber attached to an air compressor.  Air is forced into the pressure pot, which shrinks bubbles so that they cannot be seen by the naked eye.

Pressure Pot:  Chamber used for pressure casting.

Resin: A common term, defining a class of organic substances which may be natural or synthetic, which can be thermoplastic or thermosetting.  Used in conjunction with hardeners to form a semi solid to solid substance.  Can be mixed with fillers, stabilizers, pigments and other inclusions to form a final design.

Rotational Cast:  Referred to as spin-casting or slush-casting; 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: Room Temperature Vulcanizing.  Refers to a rubber material that cures completely at room temperature. Most common for making poured molds.

SDS:  Safety Data Sheet.  Contains information on chemicals, including composition, potential hazards and safe use instructions.

Sealer or Sealing Agent: A glue or aerosol sealing agent.  Necessary for porous models before using as a mold template or for porous inclusions that will take up a moisture stain when placed into resin.

Shelf Life:  The period of time a product can be stored and remain suitable for use.

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

Silicone: A rubbery type resin 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. Great for making quick molds.

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.

Thermoplastic:  Resins that will (re)melt when heated.  Can be repeated many times.

Thermosetting:  Resins that will set permanently after heating.  These are the resins we use in the jewelry making and crafting.

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 ultraviolet or sunlight to cure.

Vacuum casting: Process where resin is placed into a chamber and the air is removed with a vacuum pump.  Air bubbles are forced to come to the surface and evacuate.

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

11 Comments

julie

When a description for a tabletop suggest 2 pours. What is the timeframe between? Do I wait for the first to harden?

Reply
Katherine

@Julie, you don’t need to wait for the first layer to harden, but at least wait for it to be semi solid (i.e. a semi-solid gel) before pouring the next layer.

Reply
Katherine Swift

Soft cure is where the resin has hardened enough to demold, but may still be dentable.

Reply
Elaine Summers

I will be pouring epoxy resin over jewelry that is on a piece of marine plywood. I want the jewelry to be encased and stuck to the wood when I’m done. Do I have to glue the pieces down first? or if I have an edge, can I pour the resin and everything will stick in place?

Reply
Katherine Swift

I might glue them down just a tad to make sure they don’t shift during the pour. Otherwise, they should stick fine.

Reply
CYNTHIA

I’d like to make a silicone mold for a piece that is too large to cover in the 3 minutes pot time. If I mix in batches and make the mold bit by bit, will the new batch stick to the previous one?

Reply
Katherine Swift

You risk introducing bubbles that way. I would suggest using a silicone with a longer pot time.

Reply

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