HOW TO USE EPOXY RESIN: TIPS AND FACT SHEET
Epoxy resin is a two-component thermodurcisable liquid polymer. Beyond the ‘technical’ definitions, epoxy resin is a liquid product that, if exposed to a minimum temperature of 10 to 15oC, begins to catalyze and becomes solid. Here are some ‘fundamental’ points for those who use for the first time
times this product.
HOW DO I DOSE THE RESIN?
Being a bi-component, you have 2 vials at your disposal, one containing the resin “A” and the other the “B” hardener. Provide an electronic scale to weigh the grams and a container to mix the two components A and B.
1. Pouring an amount of A into a container, trying to get a round figure in grams (e.g. 200g), this will make it easier for you to calculate the amount of C-component hardener you will need to add
to make your blend corely.
2. On each bottle is written the report of use .
Let’s take an example with: 100A:60B.
The grams of A previously weighed (200g) are multiplied by 60, then divided by 100, to get the amount of B in grams to add .
Practical example (report 100:60): 40g component A. how many B components
Should I add?
40/100 solution – 0.40 to 0.40×60 – 24. So we get 24g of B.
This formula can be used for any usage ratio, 100: 50, 100: 30, etc…
HOW TO PREPARE THE RESIN?
Once you have prepared your two components, pour into a container A and B, the resin should be mixed for at least 2-3 minutes (When you mix, you must change direction regularly and especially scrape the sides of your container well). This phase is fundamental, if your mixture is not done correctly, at the molecular level, your mixture will not be homogeneous, your resin will not harden or partially and it will be opaque in places.
HOW MUCH IS THE RESINHARDENING?
The hardness of the resin depends on the formulation, rest time and temperature of catalysis. In addition, the mechanical resistance of the resin continues to increase up to 4-5 days after application. After 24 hours it may therefore still seem soft, but in the following days it will continue to harden to become like a plastic “hard” (say “simili-plexiglass”, for comparison).
HOW LONG DOES IT TAKE FOR EPOXY RESIN TO SOLIDIFY?
CAN THE HARDENING PROCESS BE ACCELERATED?
The speed of chemical reactions is influenced by the temperature of the room in which you work. A low temperature will slow down the chemical reaction and may prevent the hardening of your resin. high temperatures can, on the contrary, speed up the reaction.
Being a “THERMO-DURCISSANT” polymer, the more it is exposed to heat, the faster it catalyzes. In general, every 10oC more, the time of catalysis is reduced by half. Example. 20C at 3am, 30C at 1.30am, 40C at 1.45am.
To speed up the catalysis, it is enough to maintain your mixture of A and B
obtained near a heat source (even a simple radiator). However
Be careful not to heat a resin thickness of more than 1 cm. In fact, the
resin may overheat due to the mass effect (explanations
A term for exothermy (i.e. heat release) that occurs when resin is poured to high thicknesses (greater than 1 cm).
Indeed, the molecules of A, by binding to the molecules of B, release heat, which is immediately dispersed in case of minimal thickness. On the other hand, when the thickness of the drip is greater than 1 cm, the heat is dissipated more slowly, and therefore the resin begins to heat up. This warming accelerates the reaction even more, causing an even higher increase in temperature. For this reason, it is necessary to avoid the use of high amounts of resin in one pour at a time, in order to prevent it from ‘cooking’ (creating cracks, bubbles and blackening of the resin).
THE YELLOW RESIN?
All resins (even enriched with UV filters) sooner or later, if exposed to sunlight, will tend to change color, taking on an amber hue.
This may take a few weeks or years depending on the
sun exposure (outside, they tend to turn yellow faster), depending on the thickness of the resin (the thicker the resin and the earlier the yellowish tint appears) but also depending on the type of dye used.
For example, if the resin is colored with an “intense” color such as red or black, the yellowing will not be visible, while if it is white or pink, it will be visible early. Resins are usually characterized by low yellowing and can then be used to create objects that must not change colour for several years if they are kept inside a home, such as paintings, tables or jewellery.
HOW TO ELIMINATE SUPERFICIAL OR SMALL OPACITY
FORMED RIPPLES BARELY SOLIDIFIED?
These superficial opacities (especially in cold season) are the result of the effect of moisture in the environment, which creates a layer on the surface of your resin. Moisture is the enemy of epoxy resin. In case of high atmospheric humidity (rainy or foggy weather) the resin components may react with moisture in the air. This will not alter the strength of your resin however it can lead to the formation of a whitish veil (carbamation phenomenon) unattractive.
At first it is difficult to see, but to solidification, one can perceive opaque prints and in some cases even a corrugated film. To avoid this phenomenon, several rules must be followed:
1) Work in a low humidity environment (dehumidified or warmed up the room in which you work the resin).
2) Heat the 2 components separately before mixing them (for example, by holding them on a radiator)
3) Mix the resin with the hardener and apply it only when it starts to heat (so the reaction starts when it is still in the container). This is essential, but requires a minimum of
attention. In fact, the resin (depending on the amount prepared (due to the mass effect) may take about ten minutes to heat up.
It must be checked every 5 minutes and as soon as it reaches 40oC (slightly warmer than the temperature of a hand), it can be applied. In this way, some of the molecules have already reacted and are therefore less vulnerable to ambient moisture. Be careful not to wait too long before sinking, otherwise you may have the resin solidified in the container! A good rule is not to apply it in the evening or when it rains (as humidity increases). Do not apply to media that still contain moisture, such as fresh cement or undried wood.
HOW DO YOU POLISH THE RESIN?
There are several methods. It all depends on the size and regularity of the surface to be polished: the larger the surface (or irregular, like a jewel or a miniature), it is better to use a varnish.
Ideally, the transparent polyurethane spray used for the lashing of
Furniture. In the event of unavailability (as an easy alternative to
find), you can use the clear acrylic spray varnish available at hardware stores. In any case, at least 2 to 3 layers of spray are needed to get a good finish.
The method that guarantees the best aesthetic effect is manual polishing with abrasive paper (up to 1500 grains),and successively end with the classic polishing (i.e. polishing paste) which is used to polish the plastics of the car fires. However, this technique requires experience and an orbital polisher, otherwise there will always be scratches and irregularities.
Recommended only for professionals with adequate equipment, for items not too large and regular enough.
Another method is to apply an epoxy resin finish (using a brush (or as a drip) after polishing with 400 grain abrasive paper). The advice is to wait for the resin to become more viscous (by letting it sit in the container after preparing it) reaching a consistency closer to the “honey”. At this point, you will be able to start applying it with a brush (or dripping, if the objective is to get the mirror effect).
HOW DO I REMOVE AIR BUBBLES FROM THE RESIN?
To eliminate 100% bubbles degassers are necessary, but it is still possible to use some tricks that can help minimize the presence of bubbles in creations.
1) Mix the resin longer, but in a more delicate way.
2) When pouring epoxy resin, try not to drop it on top, but pour it as close to the surface as possible.
3) Once the resin has been mixed, let it rest for a few minutes, to bring the air bubbles up.
4) Once the resin is poured, pass a heat source (thermal gun or flame, NOT hairdryer) to burst the bubbles on the surface.
ONCE HARDENED, CAN THE RESIN BE SMOOTHED, CUT OR PUNCTURED?
Certainly. Once well catalyzed (24-48h), depending on the temperature of catalysis, the resin can function as a normal hard plastic.
WHAT PRODUCTS TO COLOR THE RESIN?
Technically with any dye, powders, earths, metallic pigments included. As long as the dyes are “dry” (powders or sand for example), there is no problem (provided they are perfectly dry).
On the other hand, if you want to add colors like pasta or liquids, make sure they are compatible with epoxy resins, if they do not are not compatible (for example, icings or pencils), only a few drops could be added, since the excess dosage could compromise the catalysing of the resin and its translucability (for example, by turning it into a softer or stickier product).
TO RECAP, THE THREE GOLDEN RULES ARE:
It’s pretty hard to remember all the advice; So for beginners, it’s recommended to focus on three key points:
1) Appropriate dosage and mixing with electronic scaleand mixing for at least 2 minutes.
2) Apply at a minimum temperature of 20oC by avoiding wet application conditions (or surfaces) (if you are not sure of the humidity, allow the resin to heat up before sinking, as described at the beginning of the guide).
3) Use a heat gun/flameto remove air bubbles that form on the surface of the resin.