How to Use Oakfield Clear Epoxy Resin

Welcome to Oakfield! In this guide we will lay out everything you need to know to get the most out of our epoxy resins.

Preparation

Epoxy resin is a very strong and stable material when it is fully cured – it maintains its strength over a wide range of temperatures and atmospheric conditions. However, it is the total opposite while it is curing – it is extremely sensitive to changes in temperature. Too warm and it will cure too fast and may bubble or crack, too cool and it may have bubbles or not cure correctly.

That’s why the first thing to consider in your preparation is your curing environment. It is useful to choose an environment where you can control the temperature on a continuous basis for several days while your piece is curing. For most pours if you can hold the temperature between 15 and 30 degrees C you will get good results. Temperature management becomes more tricky for large volume pours – e.g., large dining tables, or very deep pours (deeper than 50mm). If you are planning on a large deep pour, message us with some details and we’d love to talk you through it!

Ideally your curing environment will also have low humidity. When epoxy resin cures in environments with high humidity it can react with the moisture in the air, leaving a discoloration called “amine blush”. If you are in a high humidity environment, consider using a dehumidifier to reduce the relative humidity in your curing environment.

Ensure your resin, moulds, mixing equipment and work piece are at room temperature before pouring. For example, if your mould and timber have been sitting on a cold garage floor for a while, bring them to your pouring area and leave them there for a few hours to warm up.

The curing environment should be free of dust and contaminants. Give it a good dusting down and vacuum before you begin. Don’t use any candles, fireplaces, insense or automatic air fresheners in the area while resin is curing.

Prepare your mould to ensure that it is watertight with no leaks. You can use silicon from a caulking gun to seal any gaps. Coat the mould with a material that the epoxy resin doesn’t bond to. There are lots of options for this but we prefer to keep it simple and coat the interior of the mould with 3M Packing Tape – it’s cheap, available everywhere, and the cured epoxy comes right off it, no demoulding sprays required.

Always use nitrile gloves and a mask when using uncured epoxy resin.

Mixing and Pouring

Warming up the Part A of the resin before mixing gives fantastically clear results. Warming up the resin reduces its viscosity (i.e., makes it more runny), which makes it easier for it to disperse air bubbles. Run a sink full of hot water and place the Part A bottle in the water for 20 minutes before mixing.

A common pitfall for beginners is to try to re-use mixing equipment – containers, stirring sticks, etc. This leads to contamination of the resin and ultimately compromises your results. We strongly recommend using fresh, new, clean equipment and a new pair of disposable gloves for each pour.
Mix Part A and Part B in a new, clean mixing container. Any clean plastic container will work great. There are mixing containers available in our online store. The ratio of Part A and Part B depends on the type of resin you use. Ensure you only use the Part A and Part B of the same product – for example, you cannot use the Part A of Deep Pour with the Part B of Clarity Cast.

• Deep Pour: Mix 2 parts Part A with 1 part Part B by volume. For example, 10L of Part A with 5L of Part B.
• Clarity Cast: Mix 2 parts Part A with 1 part Part B by volume. For example, 2L of Part A with 1L of Part B.
• Ultimate Glass: Mix 1 part Part A with 1 part Part B by volume. For example, 1L of Part A with 1L of Part B.

You can add any pigment powders, mica powders, dyes, inks or pastes before mixing. Have fun experimenting with different colours and textures! Any tinting product will work great in any Oakfield Clear epoxy resin. We have a range of mica powders in stunning colours available to purchase in our online store.

Mix well. We recommend stirring by hand with a wooden stirring stick for at least 4 minutes. Some people prefer using a drill with a mixing bit – this is certainly easier but we find this introduces more air bubbles into the mixture. Periodically scrape down the sides and the bottom of the container to ensure that all the resin is mixed. If you don’t thoroughly mix the resin in this way, it can lead to sticky, uncured parts of resin on your piece. Don’t “whip” or “beat” the mixture, as this will introduce a lot of air which can lead to bubbles. A deliberate slow stir will do the job.

Once Part A and Part B are mixed, the chemical reaction that cures the epoxy will “kick off” after some period of time called the “working time” or “pot life”. After the working time has expired, the reaction will start and the mixture will thicken, making it more difficult to work with. Hence, its important to get your work done inside the working time. The working time period depends on the room temperature and the volume of epoxy you’re working with, but the following can be used as a rough guide:

• Deep Pour: 4 hours working time
• Clarity Cast: 1 hour working time
• Ultimate Glass: 1 hour working time

Pour the mixed resin immediately. You cannot reclaim any unused resin for later. Give the resin ample time to settle in to all the cracks and crevices of your work. Now is the time to watch out for any leaks in your mould. If you see any resin leaking out of the mould you can quickly patch it up with more silicon from a caulking gun. Pay attention to the maximum depth of the pour and do not exceed the maximum pouring depth allowed by the resin you are using:

• Deep Pour can be poured to a maximum depth of 50mm
• Clarity Cast can be poured to a maximum depth of 20mm
• Ultimate Glass is suitable for smaller casts and surface coats a few mm thick

Note that pours deeper than 50mm using Deep Pour are possible if you are willing to go to some effort to manage the temperature. Message us with the details of your project and we’d love to talk you through it!

Curing

The chemical reaction between Part A and Part B is what causes the resin to cure. The chemical reaction is known as an exothermic reaction – that is, it generates heat. You may notice you can feel the warmth if you hold your hand over the resin. Don’t worry, this is normal!

Bubbles may appear in the surface of the resin. Mixing and pouring may have introduced air in the resin, or air bubbles may have been trapped in the work piece you are casting, or air bubbles may be released from certain moulding materials such as silicon (a process known as “outgassing”). In any case, we recommend popping out any bubbles using a heat gun or butane torch. Be careful not to overheat the resin while doing this, as this may accelerate curing.
Note that bubbles may reappear over time. We recommend periodically checking the resin and popping out any new bubbles that have appeared.

The resin will gradually thicken over time, and at some point it will become hard. The exact point in time when it hardens is not easy to predict – it depends on how much resin is used, how deep it is poured, and the ambient temperature. Paradoxically, the deeper the pour is the faster it cures.
You may be tempted to put your little artistic swirls in the resin as soon as its poured – you can, and it doesn’t do any harm, but your work will be quickly undone as the resin settles. You will need to wait for the right time in the curing process to put your swirls in. Ideally the resin will be the consistency of thick honey – this is thin enough where its still possible to swirl the resin, without being too thin that the swirls will dissipate. Knowing when the time is right to do this is more art than science, and takes practice. Eventually you will get a feeling for the curing behaviour of your resin in your environment. In the mean time, we recommend checking your resin periodically to see where it’s up to. Remember these two pointers to help guide you – the warmer the environment, the faster it cures; and the deeper the pour, the faster it cures.

Note that once it is hardened it is still not fully cured yet – it may be hard but it can still bend and warp. Be careful not to remove it from the mould too early – if you do this it may slowly deform without the mould holding it in place. The demoulding time varies depending on volume, but we generally recommend the following:

• Pieces poured with Deep Pour demoulded after 7 days
• Pieces poured with Clarity Cast demoulded after 48 hours
• Pieces poured with Ultimate Glass demoulded after 24 hours

Machining and Finishing

Once fully cured, epoxy resin can be removed from the curing environment and can be taken out of the mould. It is now very resilient to a variety of environments, and is safe to touch.

Epoxy can be machined in a similar way to hardwood. Fully cured epoxy is very hard – we treat it with our tools in the same way we would treat Jarrah or other timbers on the hardest end of the scale. It can be sawn, drilled, planed, routed in the same way as wood, with the same tools.

Because of the hardness of epoxy, a general rule of thumb when machining epoxy is “less is more”. You’ll get better results with shallow cuts repeated many times, for example, rather than a single deep cut. If you can control the speed of your tools, e.g., if your router has a speed setting, slow it down. Move your tools slowly in the epoxy. This is easier on your tools and reduces the risk of burning your piece.

All our resins respond extremely well to high speed machining, such as CNC routing or lathe turning, with a predictable uniform density and no chipping or tear-out.

Always wear a face mask when machining and sanding epoxy. We strongly recommend using a good dust collection system, either with a shop vac or a larger dust collector.

Epoxy resin requires some slightly different finishing techniques than what would normally be used for timber. Unlike wood, epoxy is not porous (liquids do not penetrate it), and it is translucent (you can see through it). Therefore, epoxy responds well to fine sanding and polishing, and finishes that leave a fine translucent film. Don’t use stains – if you want to colour your epoxy, do it with pigments in the mixing stage.

Note for flood coats with Ultimate Glass, no further sanding or machining should be performed after the coat has cured. No amount of sanding or polishing will get the surface of Ultimate Glass to be smoother, clearer and shinier than how it appears freshly cured. If there are divots, bubbles or other imperfections in the coat, you can sand over these and re-pour the coat.

Finishing is a very personal thing – it depends greatly on personal taste. Because of this there are a practically infinite number of ways to finish epoxy resin, and just as many comment threads on the internet telling you different do’s and don’ts of finishing epoxy. Therefore, we recommend you experiment with different types of finishes to see what works best for you. As always we love talking about these details with our clients, and we’d love to hear from you to hear your finishing suggestions!

One finishing product that we particularly like is Kustom Grit by Kustom Creations, available in our store.