Common resin crafting terms – learn the resin lingo


common resin crafting termsCommon resin crafting terms

Have you ever felt like there is a lingo to working with resin that you just don’t quite understand?  I get it!  I felt the same way when I first started.  Here are definitions to some common resin crafting terms so you can feel confident right away knowing what all these terms and phrases mean.  They are important to make sure you understand your resin products and how to use them!

RESIN CRAFTING Terms beginning with letters A through F

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 that 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 the 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; 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 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 the 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.

RESIN CRAFTING Terms beginning with letters G through P

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 the resin to cause it to cure.  May also be referred to as catalyst.

Inclusions:  Anything being added to the 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.

Like this post? You may be interested in  Resin Obsession Super Clear Resin FAQ

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

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 it 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 the 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 CRAFTING Terms beginning with letters R through Z

Resin: A common term, defining a class of organic substances that may be natural or synthetic, which can be thermoplastic or thermosetting.  Used in conjunction with hardeners to form a semi-solid to a solid substance.  Can be mixed with fillers, stabilizers, pigments, and other inclusions to form a final design.  Our resin buying guide details resins and which one is right for your project.

Rotational Cast:  Referred to as spin-casting or slush-casting; a 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.  This 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 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 low viscosity, will flow easily.  A material, like peanut butter, with a high viscosity, will not flow easily.

Eager to get started crafting with resin but overwhelmed with where to start?  I felt the same way when I started creating with resin.  It’s why I wrote the book, Resin Fundamentals.  I share everything beginners need to know to have success with resin.  It’s what I wish someone had shared with me about resin!

Unpublished Blog Posts of Resin Obsession, LLC © 2020 Resin Obsession, LLC

32 thoughts on “Common resin crafting terms – learn the resin lingo

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

  2. @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.

  3. 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?

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

  4. 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?

  5. Hi and thankyou for any advice given. What is the best resin/brand to pour into a closed Terrarium for the ocean? I have tried a variety and living in Hawaii with the humidity I have been wasting a bit of my resins. Also, how do you seal your substrate (soil/gravel) before pouring your resin in? I have tried tape, plastic, mixture of glue and spray sealants.
    Any advice is deeply appreciated. By the way, your Terrariums pieces are beautiful and inspirational!
    Kind Regards,
    and thank you.
    Wendy park

    1. Hi Wendy, I’m afraid being in Hawaii, you are limited to the resins you can use because of shipping restrictions. I’m afraid you are going to have to ‘make do’ with whatever you can find in your area, although a casting resin is best. This article shows how to make a koi pond with resin. The artist did not use anything to seal the gravel first.

  6. how do I keep my add ins from sinking to the bottom (top) when working with cube, sphere, or pyramid molds?

  7. hello. I am working with food safe resin to reapply labels on slumped wine bottles. Thinking the label will go on the bottom of the bottle. Is it necessary to tack the label to the bottle prior to pouring the resin on? Or will the resin seep thru the paper, allowing for it to adhere? I you do re ommend affixing it first, what product would you recommend useing? Thank you so much fir your thoughts!

  8. I have a skull that cut out of a raw crystal, so there’s actually the crystal poking up on one side of it n i want to encase it in resin or epoxy, which would be best? Its smaller than a baseball, planning on using it for a shift knob.

  9. Hi there, I wonder what resin or adhesive should be best used for delicate inlay work on rings. I need a good crystal clear resin or glue that can fix nicely the crushed opal and turquoise stones I put on rings. It needs to be something that is hard enough to polishes nicely on a buffing wheel. Thank you for your advice.

  10. Hi I am wanting to make pandora style beads with cremations inside using a UV resin but I am finding once in hot water they go a bit floppy I need them to be as hard as glass have you any suggestions plz

  11. Hi! In your resin buying guide, you have ‘x’ in sections like “casting resin” and “suitable for artwork”.. does the ‘x’ mean that is is NOT suitable or it IS suitable?

    Thank you for the clarification. I’m new and have never played with resin before but I’m very interested in trying it out!

  12. Guidance please. I want to fill 1 1/2 “ scallop shell with a stop of Velcro, small weights then resin. Making decorative weight belt for free diving. Velcro is so I can add or take shell depending on how much weight I need. I’m hoping to get each Shell to weigh close to one pound. Which resin would be best to order from you & will the resin stick to a natural shell?

    1. Hi Patricia, it sounds like you will use less than 3 ounces of resin at once in this shell. In that case, the Resin Obsession super clear resin works great for a shell project. You can buy it in our store here: What I don’t know is how well the cured resin will handle prolonged saltwater exposure. If you give this a try, will you let me know how it goes?

  13. Great dictionary of terms to have at hand! Perhaps you could also clarify “casting epoxy resin” and “clear casting resin”.

    1. Hi Valerie, happy to clarify! Casting resin means that it is meant to be used in molds. Clear casting resin means that it cures clear once cured.

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