Rijacki Design

Alchemist’s Workshop Basics: Epoxy Resin – Demystifying Resin and Related Terms

Ms_Rijacki2When ever I work with epoxy resin, I feel a bit like a mad scientist in my alchemist’s workshop mixing up chemicals, cause I am. Muhahahaha, and I shall take over the world! err umm…

This blog post is intended to demystify the various terms information about working with epoxy resin.  You should not feel intimidated by epoxy resin. It’s actually pretty easy to work with, once you know a bit about it.

Epoxy resin is generally two parts which need to be mixed before use. The ratio of the parts depends on the brand of the product. Once the two parts are mixed together, they begin a chemical reaction which makes the resin increasingly less liquid as time passes until becomes as hard as it will ever get. This process is called curing. Epoxy resin generally fully cures in 24-hours which is why it is sometimes called 24-hour resin.

TIP: Each time you open a new box of resin or a new resin “kit”, read the instructions that came with it. Look for the important bits as outlined below. Even if you’ve used that particular resin before, still at least glance at the instructions to make sure nothing has changed with their formulation.

This posting keep growing and growing so I have had to split my intended coverage into parts (and even then this part got to be rather long as I kept thinking of things that should be included even if just briefly). As my college professor for Creative Writing would say, “It’s growing the tooth and claws of a novel.” At some time, later, many of these sections will be blog posts of their own to expound on them more deeply.

Alchemist’s Workshop is an on-going series of posts on working with resin, clay, and various other mixed media.

Toxicity:

Most epoxy resins sold for jewelry making or to the hobby market have some claim to being “non-toxic”. By the strict guidelines of the US Federal Hazardous Substances Act, they don’t contain chemicals deemed to be toxic, i.e. those which would cause long term effects such as cancer, birth defects, and the like, or would cause personal injury from being inhaled, absorbed through the skin, or swallowed. However, epoxy resins should not be considered harmless. Because epoxy resins are made from chemicals, each should have a Material Safety Data Sheet (MSDS) which lists the hazardous material contents and safety precautions for working with them.

Suggested Safeguards while working with epoxy resins:

  1. Avoid to resin on your skin. Wear non-porous gloves such as nitrile, vinyl, or latex.
  2. Avoid getting resin in your eyes. Wear goggles especially when sanding any resin pieces and even while pouring.
  3. Avoid breathing the resin fumes. Work with epoxy resin in areas of good ventilation and/or use a fan to keep the air moving. For other resins, such as polyester, you may need a respirator and to work outdoors exclusively.
  4. Avoid breathing resin particles. When sanding, wear at least a paper mask.
  5. Avoid getting resin on your clothes. Wear an apron. Resin on cloth cannot be cleaned off. It will permanently bond to the fibers even without curing.
  6. Avoid getting the resin in contact with anything you might put in or near your mouth. Once you have used it with resin, never use any mixing cups, stir sticks, molds, or other tools with any foods or anything that might come in contact with food.
  7. Keep pets and children away from liquid resin.
  8. Read the instructions for the resin brand every time you open a new package of the resin.
  9. Read the MSDS (Material Safety Data Sheet) for the resin brand.

While the epoxy resins likely won’t kill you or cause permanent effects if you don’t follow these guidelines, these safeguards are pretty mild and easy to follow. In a nutshell, unless you’re sensitive to one of the chemicals in the substance, working with epoxy resin is unlikely to cause you any health issues.

Self-Doming: 

All liquid is self-doming. Resin is a liquid.

Carefully put a drop of water on a flat surface such as a small tile. Look at that drop from the side. You’ll see how it is forming a ‘dome’ with the “skin” of the water, surface tension, holding the liquid in that shape. If you don’t break the surface tension, the water will remain domed until it evaporates.

Same with resin, if you don’t break the surface tension it will remain in a dome until it cures and hardens. However, those resins which start out thicker, more viscous, it’s easier to control that surface tension and keep it in a dome out to the edge of your project. So, while all resin is self-doming, the thicker resins are easier to get the dome where you want it and to keep the surface tension.

With all resin, like water, if you want to keep the dome you need to make sure the surface tension doesn’t get broken.

Shake the surface the water drop is on. The surface tension of the water dome will break and the water will flow all over. The same thing will happen with resin if move it abruptly.

Dry off your surface and put down another drop of water making sure the surface tension is keeping it in a dome.

Tip the surface to the side until the drop slides off. The weight of the water will break the dome and the water will flow. If the drop is small, it might keep most of its shape if the surface tension doesn’t break. If you don’t have resin on a level surface while it is curing, the weight of the resin could break the surface tension which will cause the dome to break and the resin to flow where you don’t want it. Just like the small drop of water, the resin on the uneven surface might have a lava-like dome over the side of your project if the surface tension only moved but didn’t break.

On a dry surface, put down another drop of water. Carefully, with a toothpick, drag the water over, don’t break the surface tension at the bottom of the drop. You can move the dome to spread it out, but you have to be careful while doing so. It’s very easy to break the surface tension at the bottom and have your dome collapse. Put a second drop of water near your first. Carefully drag your first drop into the second. The drops will combine to be come a single drop, expanding the surface tension to include both. Carefully add another small drop of water to the one on the surface. Add the new water close to the surface of the drop so you expand the surface tension and don’t break it.

On a wet surface, try to place a water drop so it domes. This isn’t possible because the new water you’re adding can’t create the dome with the surface tension of the water that was already there. Same with resin, if there is resin across the surface including areas where you don’t want the dome, you won’t be able to make a dome there. Once the surface has cured, though, you can add a dome over it.

Exploring surface tension (not just for kids *grin*): http://buggyandbuddy.com/science-experiments-kids-exploring-surface-tension/

These same things can be done with the surface tension of the resin dome. Always do things careful and slow with the dome so you don’t break the tension.

TIP: If you have a deep area for the resin, such as a bezel, do a fill first, let it cure, and then add a dome. Don’t try to do it all in one go.

Magification with the Dome:

Because of light refraction, a liquid dome has ‘built in’ magnification. A cured resin dome retains that magnification. The shape of the dome will govern how much it magnifies the surface below it. The dome not only has a nice finishes surface but it can be used to highlight your piece. However, there can be a bit of distortion around the edges with the magification not being equal across the whole surface. The lower the dome, the less magnification effect.

Self-Leveling:

All liquid is self-leveling. Resin is a liquid.

water_glass_restaurants_315 304Get a glass and pour some water into it, make sure the water touches the sides of the glass. Look at the glass from the side. Do you see the water line? Put the glass on a flat level surface, the water line is even with the bottom and top of the glass. Tip the glass to the side, but not all the way over, and the water is at an angle to the top and bottom of the glass. This is self-leveling.

When the surface tension is ‘broken’ by touching the sides of a glass or other container, the liquid will make a level within that container. For resin, when it is very liquidy, it will act just like that water and level itself within the mold or bezel just like the glass of water. When the resin gets thicker but hasn’t fully cured, it will still act just like any other liquid albeit slower.

Because of resin will “self-leveling”, it is important to cure your resin on a flat and level surface. If your surface is not level, the resin in your mold or bezel will be angled.

Self leveling also refers to the fact the resin, like water, will seek to fill all the available space, if its surface tension is broken so it’s not in dome. When you put in enough resin to fill the bottom of a bezel it will self-level to fill the corners. If you have inclusions (embellishments included in the bezel or mold area), the resin will flow around them or over them, if enough resin is added just as water would do.

TIP: If you have a very deep area for the resin, such as a deep bezel or a mold, you can pour the resin in stages and allow it to cure or partially cure between to ensure an even, level fill.

Ratio: 1 to 1, 2 to 1, and so on

5639_190-150x150Two part epoxy resin usually comes in 2 bottles with one labeled A and the other B, Resin and Hardner, or some similar designation to distinguish one bottle from the other. In the instructions which come with the resin (read the instructions each time you open a new box, even when you’ve used that same product before) there will be information on the ratio of one part to the other part. The 1 to 1 resin is the easiest; you need equal parts of both liquids. The 2 to 1 is double of one liquid in relation to the other (the instructions will note which is the 2 and which is the 1, bottle size might also give it away *smirk*).

Resin Hates Water

HygrometerIf there is too much non-resin liquid in your batch of resin (such as from liquid pigment) or even just too much moisture in the air, resin won’t cure fully or correctly. With some resin formulations, too much moisture in the air may result in the resin curing with an oily feel that remains with the piece indefinitely. For others the piece may be perpetually soft and not rigid. Keeping water away from the resin itself is paramount. It’s best to plan your resin mixing for days when it’s dryer or in a workshop that has drier air.

If you live in a damp or humid climate, you can purchase a cheap hygrometer to monitor the relative humidity in your work space.

The type/brand of resin you’re using as well as other environmental aspects can affect how the resin copes with different levels of humidity. Some resins respond well to adding in a small extra bit of the hardener than normal to offset non-resin liquid in the mix. Keep notes on your experiences with resin and note the humidity and if you added extra hardener. You’ll soon find the right levels for the area you’re in and the resin you’re using.

Resin Likes it Warm

04006-800x800_2Cold temperatures can slow the resin curing process or even cause it to not sure properly at all, but too warm and the resin will cure a lot faster than normal, reducing the amount of time you have to work with the resin before it gets too thick.

Ideal temperature for epoxy resin is 75-85 degrees Fahrenheit / 25-30 degrees Celsius. (Ideal temperature for me personally is 65-70 degrees Fahrenheit or lower, so this is actually the hard one for me).

In a cooler climate, you can offset the heat issue with keeping the work room heated (which also helps to dry the air, too), use a heat lamp in the curing area (but only when you’re in the room), and/or create a “hot box” to trap heat in the curing space.

Pot time

latestTwo-part epoxy resin has a relatively long working time also called the “pot time” (i.e. the amount of time it can stay in the pot without curing to a solid substance). From the time you begin to mix the two parts together until the time it more resembles cold taffy rather than any liquid, is various stages of the working time.

With most epoxy resins at the ideal temperature, you have about 15-20 minutes of liquid pouring. During that time, the liquid will be getting thicker and thicker.

The liquid stage is followed by what I like to think of as the “frosting stage”. This is when the resin resembles frosting. It flows very slowly, but does still flow and will still self-level but is too thick to dome. Carefully adding in inclusions during this stage can suspend them in the resin instead of them dropping directly to the bottom when in the more liquidy stage.

The frosting stage will pass all too quickly into the cold taffy stage, lasting only about 5-10 minutes. The resin will still flow extremely slowly in the cold taffy stage, but is nearly unworkable. This is a great time to add inclusions you want to bond but only want on the back or top of the piece (back if it’s in a mold, top if it’s in a bezel).

Partial Cure, Soft Cure, and Fully Cured

Just as there are stages of the pot time, there are also important stages in the curing time.

  • Partial Cure: For most epoxy resins, at 3-6 hours (in ideal temperature conditions), the resin will be partially cured. It will mostly keep its shape but is still a little sticky. If you touch the resin at this time, your fingerprint may be forever captured in your project. This is a good time for a second pour to add in a ‘floating’ inclusion or adding on a thin layer of a colourant you want only at the back (such as a dusting of mica for a background sheen). If you’re working with a mold, you cannot unmold the item at this stage. If you do unmold it, it could lose some of its intended shape as the resin is still an extremely slow moving liquid at this point.
  • Soft Cure: For most epoxy resins, at 6-12 hours (in ideal temperature conditions), the resin will be soft cured. The shape is frozen. Handling the resin won’t leave fingerprints embedded in the surface. The resin doesn’t feel sticky at all. If you brush on a powder, it won’t bond into the resin. But, the resin is soft-ish and can be manipulated before it achieves its final hardness. If you’re using a mold, some molds can be de-molded at this time. If so, when the resin is soft cured, you can trim off unwanted edges quite easily with a pair of scissors. In the soft cure stage, resin has not formed its final, unalterable, bond. It’s possible, in many cases, to remove unwanted over-spills by peeling away the unwanted resin. There are other things you can do to manipulate soft cured resin, but those can be covered in later posts (this one is already too long).
  • Fully Cured: For most epoxy resins, at 24+ hours (in ideal temperature conditions), the resin will be fully cured. This is the point where the resin should feel as hard as glass. The resin won’t change shape at all after this point. It’s solid and frozen permanently.

Bubble Bubble Toil and Trouble

2014_09_2923_52_10999_Bubbles happen. They’re inevitable, but they’re also somewhat avoidable. Bubble avoidance is a big part of working with resins. Bubbles are another way resin shows it’s displeasure with cooler temperatures, bubbles slowly form and trap themselves in your finished item.

  1.  Before you mix the resin, warm it up. Put the 2 bottles into a warm water bath. Make sure you dry each bottle off thoroughly before you add it’s contents to your mix or you’ll fall into the resin hates water zone.
  2. Don’t add in bubbles. Resist the urge to whip the resin at any stage. Mix the resin slowly and deliberately, avoiding the introduction of bubbles. As the resin gets thicker, the urge to whip it might increase. Resist that urge. It’s far too easy to add in bubbles the thicker the resin becomes and far more difficult to get rid of them.
  3. Heat up the mold or bezel. Using an embossing gun or blow dryer. Heat up the mold or bezel before you pour in the resin. Careful not to over heat. Using a water bath to heat these items is not a good idea because it would be difficult to keep dry the area you want for resin and resin hates water.
  4. Pour slowly. Again, avoid adding in bubbles. Even though the pot time isn’t long, still work slowly and carefully.
  5. Use heat after you fill: After you’ve poured resin into an area you can use heat from an embossing gun, a blow dryer, your own breath, a lighter, or any other targetable heat source. For all three, careful how much air your moving. If you have domes be very careful not to break the surface tension with over zealous heat application. If your bezel is metal, careful, too, you don’t over heat the metal and boil the resin. If you’re using a lighter or other open flame, be wary of the fumes close to the surface of the resin. You don’t want to set your project (or anything else) on fire  while over-zealously removing bubbles.
  6. Use a toothpick: You can guide most bubbles out to an edge where they can escape or even pop them in place with the use of a carefully applied toothpick.

Side note: You’re most likely to notice small or obscure bubbles only after the item has completely cured and you’re taking photos of it to post online. Once you notice them, though, your eye will be drawn to them every time you look at the piece no matter if anyone else notices them or not.

Inclusions and Embellishments

20140710_074830_Anything you want to include in the resin project that isn’t resin falls into the categories of inclusions and embellishments. Inclusions and embellishments are items like paper , stickers, glitter, beads, small objects of all kinds, plant or animal material, minerals, fabric, etc. The list is really endless and includes anything someone’s imagination can conceive of being part of a resin project. Anything you put in or under resin can be considered an inclusion.  Embellishments are usually items placed on or just sticking out of the resin. But, the terms are often used interchangeably.

There are a few things to keep in mind for inclusions and embellishments: resin is a liquid, resin hates water, resin will fill in all possible nooks and crannies, objects can sink in the resin liquid if they’re heavier than the liquid, and inclusions can add in bubbles.

  • Resin is a liquid:  Resin will soak in to anything porous that hasn’t been sealed. If you want to include paper, fibers, fabric, flowers, wood bits, fur, or anything else that can soak up a liquid, you will need to first seal it. There are a lot of different types of sealant and some are more suitable for particular substances. Paper can be sealed with things like multiple coats of ModPodge or other glue-like products. Paper can also be sealed with clear packing tape as long as there are no teeny tiny gaps for the resin to seep in under. If the porous items aren’t sealed, the resin will soak in and could turn the item darker but usually inconsistently.
  • Resin hates water: Anything going into the resin should be completely dry. Sealants should be allowed to dry for several hours or even overnight. Organic matter that’s not going to be pre-sealed needs to be thoroughly dry as well.
  • Resin will fill in all possible nooks and crannies: Resin, like the liquid it is, will flow in and around the objects placed in it. For some potential inclusions, like faceted glass or gemstones, this will take away the effect of the faceting turning the object more ‘flat’ and unable to catch and refract light.
  • Objects can sink: Heavier objects will sink to the bottom of the mold or bezel. If you want them to be in a particular spot in the resin to appear as if they are floating, you can do multiple pours. Pour to below the point you want the item to ‘float’ at. Let the resin partially cure (at least 3-6 hours). Then put in another layer of resin with the inclusion. You can make a resin piece in multiple layers. If the layers are all the same colour or all clear and with nothing put across the layer, you won’t even see where one layer was done and another put on top. You can even add layers to a soft cure or fully cured resin piece, the resin will bond to be one with the other layers. It’s even generally possibly, with fully cured resin, to mix brands or resin types in additional layers.
  • Inclusions can add in bubbles: Just like you can trap bubbles under something you put into water, so too can you trap bubbles under and inclusion when you put it into the resin. There are tricks to avoiding adding bubbles while adding objects:
    • Before putting an object into the resin bezel or mold, first dip the object into resin. This will give the resin a place to flow to join with the other resin.
    • Slide the object in vs plopping it straight down. Putting it in at an angle will give potential bubbles a place to escape.
    • Gently press on the object once it’s in place going from the middle outwards to guide bubbles out from under the item.

Colourants (or Colorants)

CR0312-BLColourants are simply substances to change the colour of the resin in some way: dye, pigment, paint, ink, extremely fine glitter or mica, ground spices, etc. Colourants can also be considereed a form of inclusion. Colourants can be transparent or opaque.

Colourants are generally added after the two parts are mixed, though some can be incorporated into the first part (such as with pre-coloured resin). Carefully combine the colourant to the resin keeping in mind that you don’t want to add in more bubbles. One of the best ways to add colour is to mix the colourant with a small amount of resin and then introduce that small amount of coloured resin to the larger amount to stir it slowly.

When adding in colourants to your resin, there are some important considerations to keep in mind (and these might sound familiar to information above *grin*):

  • Resin hates water: If the colourant is a liquid (ink, liquid pigment, liquid dye, etc.), you should be very sparing in how much you add. Too much liquid colourant can cause the resin to cure improperly.
  • A little goes a long way: Add in your colourant in small amounts rather than dumping in a lot at one time. You can always add in more but it’s tough to take some out (though you can add in more of the clear or base colour resin).
  • Some Colourants are heavier than the resin: If the colourant’s particals are heavier than the resin, the colourant/resin might seperate with the heavier particals sinking to the bottom of where you’re working (which might be the top, if you’re doing mold work). Different substances will have different weights, best to experiment and keep notes on what works in what way.
  • Resist the urge to “whip” the colour into the resin: Avoid adding bubbles. Mix slowly!

Resin Sticks to…

.. just about anything.

Resin won’t permanently bond to wax paper, kitchen parchment paper (which is just a less waxy wax paper), silicone, silly putty, polyethelene plastics, mold release, smooth glass, vinyl, latex, nitrile, and a few other things. These can be used for molds, to cover work surfaces, to cover surfaces where you want to cure resin, to cover hands, etc. Anywhere you don’t want resin, cover it with one of these. Anywhere else, resin will stick and bond and, in some cases ruin.

Kitchen wax paper and parchment paper is sold in most grocery stores and is relatively cheap. It can be used in a large sheet or smaller sheets. It’s great for covering your workshop table area while you work with resin, in small strips for mixing small amounts of resin, on each surface where you’ll be curing resin, and can even be taped to an open bezel to make a back which will let you create a resin piece with it (careful no edges of the wax paper get exposed to the resin or it will be just paper to the resin and bond).

Molds

20141211_183550Molds can be used to shape your curing resin. Molds can be made of any anything the resin doesn’t stick to, but the most common molds are polyethelene plastics and silicone. Polyethelene plastic molds are primarily common shapes, while silicone mods have a much broader variety. Silicone molds can be formed from nearly any shape and easily hold a lot of detail. Because silicone generally doesn’t stick to the surface being molded, it’s commonly used to create molds from “found” objects (and thing found anywhere that is being used for a different purpose, more or less, than it’s original use).

There is a wide variety of pre-made Polyethelene plastic molds and silicone molds available from various retailers and etsy sellers.  Silicone molds can also come from baking and other kitchen tools such as small cake pans in special shapes, ice cube trays, fondant trays and so on. Some plastic items not sold as molds can also work well for casting resin such as very cheap plastic paint trays (see the picture with Inclusions and Embellishments above).

Warning: If you use a mold (cake pan or ice tray) for resin, you can never use it for food.

De-molding or releasing the molded item from the mold is generally accomplished by breaking suction between them. It’s a lot like getting ice cubes out of an ice tray. To aid in the release of molded resin, felixible molds are easier and ridgid ones. Some moldss may require the use of mold release which is put into the mold before the resin. Mold release will help prevent a permanent bonding of the resin with the mold surface.

Bezels

pavelka-silver-bone (1)Bezels are items with a recessed area. You can pour resin directly into the recession if it is fully enclosed. If the bezel has an open back, you can use tape and/or wax paper to create a temporary ‘back’ before you pour then remove backing to have a 2 sided resin casting permanently bonded to its frame. Bezels can be great for a variety of inclusions, especially deep bezels.

Curing the Pets

20140710_074708_…err Curing with pets (or children) in the house, or even without any. Set aside a location for resin curing that is out of the way of curious hands and paws. Cover the curing resin so stray hair, fingers, dust, and other unwanted materials doesn’t get in it.

I’ve discovered that a cheap plastic stack-able letter tray makes a good resin curing station. Not only does it cordon off a space in your work area as the resin curing zone, it also makes it possible for you to have a stack of surprises with multiple pieces curing at once. Cheap drainage pans for potted plants make good covers, so do any other empty containers, and cheap plastic shot glasses for small objects. See through covers are nice because they let you see over-spills to make a plan (or to let you have your disappointment earlier).

You also need to make sure your cover is not touching the resin so the surface tension of the resin is not broken and/or your cover doesn’t become part of your finished piece (voice of experience on this one, sadly). I also line my curing areas and all my curing surfaces with wax paper or parchment so the area the item is curing on doesn’t become part of the finished item.

 

Part 2 is Mixology, mixing up the batch of resin: Coming soon!

 

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Handmade Jewellery by Kate Ledum