Epoxy resin, what is it?

Epoxy resin, what is it?

Posted by Bawantha Perera on 27th Oct 2021

About Epoxy Resin, What is it, How to Use & How to Choose?

Epoxy resin is an extremely versatile synthetic resin that consists of two components: the actual resin and the hardener (also called catalyst). If these two components are mixed together, the material hardens within a few hours. The mixing ratio is different from brand and the type of epoxy resin, As a rule, ratio of resin and hardener is 1:1 or 1:2, or 3:1.

There are different casting resins for different applications. From fast-curing resin to slow-curing resin with an extremely hard and durable surface, there are a multitude of properties. The heat resistance and the maximum possible layer thickness are also important aspects.

Different properties of epoxy depending on the product:

  • Duration of curing
  • Maximum layer thickness per casting process
  • Adhesion to various materials
  • Viscosity
  • Final hardness after complete curing time

We will show you what to look out for when buying epoxy resin and which is the right casting resin for which application.

What applications is epoxy resin suitable for?

Epoxy resin is very versatile. Here is a brief overview of the areas in which it is used:

  • Floor coating for the warehouses, indoor car parks, shops, hotels, bathrooms, living area, garage.. etc.
  • Surface sealing. e.g. kitchen worktops (countertops), Preserve timber/wood tables.
  • Resin furniture such as epoxy resin tables.
  • Resin art.
  • Epoxy resin jewelry.
  • Repairs within minutes with UV resin.
  • Modelling.
  • Resin molding / Resin Casting.
  • Terrarium construction and aquarium construction.
  • Epoxy resin adhesive for repairing small parts.
  • Gelcoat and topcoat in boat building.
  • Renovations.
  • Waterproofing.

Buying epoxy resin - these points must be observed

Epoxy resins are available in Sri lanka by us (ArtnCraft.LK) or through few suppliers, specialist shops or online.

Which epoxy should I use for my project?

Basically, it is always about taking the material properties into account. How are these in the liquid state and in the hardened state?

Low viscosity casting resin

If the resin is thin, that is, it is of low viscosity, it is called "casting resin". This rather watery consistency is important so that the material can also reach the last crack, crack or hole in the casting mold. It usually has a significantly longer processing time and only hardens after 12-24 hours. The longer reaction time results in much less heat, which is why larger quantities and thicker layers can be processed at once.

It is therefore ideal for the following applications:

  • Pouring decorative objects
  • Sealing of cracks and holes in wood
  • Pouring furniture such as river tables
  • Molded parts in model making
  • Resin jewelry

Viscous epoxy resin / laminating resin.

The thick, highly viscous epoxy resin, on the other hand, has a consistency that is reminiscent of honey. This product, also known as "laminating resin" or "resin", is perfect for resin art or for coating surfaces. Depending on the manufacturer, it can only be poured up to approx. 0.5cm - 1cm high (Single pour, can be pour multiple layers if required).

Laminating resin is used for:

  • High-gloss sealing of surfaces
  • Resin Art : Resin Pictures, Geodes and Petri Art
  • Protective layer for paintings of all kinds and all other fluid painting techniques
  • Sealing of epoxy resin tables
  • Seal the final layer for all flat surfaces, e.g. worktops
  • Garage floor coatings
  • Floor coatings in living areas

Processing of different viscosities - layer thickness

Low-viscosity resin is perfect for casting thick layers. It heats up less quickly if it is poured thicker. With a little extra help, air bubbles can be removed from the still liquid resin layer using a Bunsen burner or hot air blower.

Viscous resin, so-called laminating resin, on the other hand, should usually not be poured thicker than 1cm. Due to the thicker consistency, the air bubbles can only escape poorly.

Resin: processing or hardening time

Processing time: One of the most important points is the processing time, also known as the open time or pot life. It defines how long the resin can be processed after the two components are mixed together.

At a certain point in time, the resin begins to become thicker or lumpy and should then no longer be processed - it no longer levels itself and can no longer be evenly colored.

Hardening time: The hardening time tells you how long the cast epoxy needs until it is completely hardened. It is often the case that a short processing time results in a shorter curing time.

But what products are there and what is the range?

Short processing times range from 20 minutes to an hour, but to fully cure may take up to 24 hours.
Long processing times range from 12 hours to 72hrs, but may take 3-7 days to completely cure.

Advantages & disadvantages of different processing times: 

Short processing time:

Advantages:

Special effects can be achieved when dyeing these resins.

Faster build-up of the layers: New layers can be poured in a much shorter time. 

Disadvantage:

Major blistering, difficult to vent.

As a rule, it tends to yellow when exposed to UV radiation. 

Long processing time:

Advantages:

Long processing time gives time to mix different colors and work carefully.

When casting transparent layers, the transitions between the successively cast layers are less visible.

Disadvantage:

More mixing cups and spatulas are needed when pouring multiple layers.

Epoxy resin, all properties summarized

The use of epoxy resin in Sri Lanka has increased massively in recent years and there is a reason for this - the numerous positive properties of this material. 

The following properties apply once the epoxy has cured. This can take up to a week, depending on the product and manufacturer. Please note the information on the respective packaging of the product. Even if the casting resin already seems dry, the chemical process takes a much longer. 

  • Very high strength
  • High abrasion resistance
  • Hardly any cracks with good preparation of the substrate
  • Good acid resistance
  • High electrical insulation properties
  • Good heat resistance
  • Hardly flammable in the liquid state
  • Low shrinkage during curing/drying, Very low degree of shrinkage from the liquid to the hard state.
  • Very good adhesive properties on most materials (except many types of plastic)
  • High weather resistance
  • Good shelf life (1-2 Years if properly stored)

The hardened epoxy resin surface has a very high durability. Mechanically it is extremely resilient. It is also corrosion-resistant and resistant to acids.

Negative properties of epoxy resin;

Epoxy also has its disadvantages, even if they are comparatively small: 

  • Lightfastness to UV radiation is not 100% guaranteed
  • Not 100% acid-resistant with highly concentrated acid
  • In the liquid state, on contact with skin, may cause allergies and rash
  • Removal of hardened resin is laborious
  • Even the crystal clear epoxy resins may get very light yellowish tint overtime.
  • Epoxy resin is very sensitive to humidity, and temperature.
  • Cannot mix any liquid (colorants) that contains water.

Is Epoxy Resin Toxic?

Epoxy resin and the hardener contain substances that should not come into direct contact with the skin. Direct skin contact can cause allergies and skin irritation. It is also advisable to use resin in well-ventilated rooms and to use a respirator with a filter and to protect your eyes. Please also note the safety instructions on the packaging.

The following protective measures should be taken when working with epoxy resin:

  • Wear nitrile gloves
  • Use a respirator with a filter
  • Wear safety glasses
  • Work in a well-ventilated area
  • Use long-sleeved clothing or wear a protective suit

The mixing vessel should not be completely filled, otherwise the liquid could spill over the edge during mixing.

If you follow these basic rules, nothing stands in the way of processing. We have put together more about epoxy resin processing in a separate article.

Coloring epoxy resin - how does it work?

Resin is usually colorless and clear. This is desirable for some applications such as pouring objects in, building terrariums or aquariums. For the greater part of possible applications, however, one would like to color the resin.

What color can epoxy resin be colored with?

A whole range of colors are suitable for combination with resin:

  • Airbrush paint
  • Color pigments in powder form (None Organic)
  • Liquid color concentrate (DO NOT use water-base colors)
  • Alcohol Inks

Paints that contain water should be avoided at all costs, as the water content has undesirable effects on the epoxy resin and there is a risk that it will not harden completely. 

Subsequent painting is also an option, but only in special applications such as terrarium or aquarium construction. A high-quality 2-component car paint can be used. 

We have created a comprehensive guide on the subject of epoxy resin coloring, which introduces the best products and tells you what to consider when coloring. Please see the Article Here

Sealing wood with epoxy resin - does it work?

This works very well, epoxy resins are also often used for this. This makes the surface waterproof and completely sealed. Possible applications in this area are:

  • Kitchen top made of wood
  • Seal tables
  • Boat repairs with gelcoat or topcoat
  • Seal any other wooden surface 

You must follow proper methods to get the best results, you can find out more about this in our guide on the subject of epoxy resin wood. 

How can you remove epoxy resin? 

The good adhesive properties and mechanical strength make it difficult to remove epoxy resin. The mechanical removal is accordingly very complex. It is therefore easier to liquefy the material and scrape it off. 

The surface is treated with acetone and then you wait an hour until the surface is slightly soft. Then a hot air gun is used to heat the affected areas to approx. 200 degrees. Only at this temperature does the resin become liquid again and can then be scraped off. 

It is important that the surrounding materials such as wood or plastic do not get too hot or burn. For more information and detailed instructions, see Removing Epoxy Resin.

How dangerous is epoxy resin?

When cured, epoxy resin is absolutely non-toxic and harmless. In the liquid state, however, direct skin contact can cause chemical burns and, in extreme cases, permanent allergies. Any vapors that may appear can also be harmful. 

Therefore, the following safety measures should be observed:

  • Provide adequate ventilation
  • No direct skin contact - wear nitrile gloves
  • Wear a respirator in poorly ventilated areas
  • Wear protective clothing or long-sleeved clothing

Is epoxy resin food safe?

Basically, epoxy resin is food-safe as soon as it is completely cured. This can take up to several weeks. Epoxy resins can be specially certified for contact with food, but most manufacturers do without them due to the high costs. 

What does resin mean? 

Resin comes from the English language and generally means resin, but is very often used as a synonym for epoxy resin. The term resin is used in particular for the use of resin in art. The properties are identical, only the name is different. 

What does epoxy mean? 

Epoxides are a chemical group of reactive, organic compounds. The epoxy resin is made from a polymer made up of several epoxy segments. 

Is epoxy resin waterproof?

Epoxy resin is completely waterproof after curing and it stays that way. This material is tight even after several years, provided that no cracks occur due to major vibrations. 

How can epoxy resin be processed/finish? 

After curing, it is basically a hard piece of plastic. Accordingly, the material can be processed in a variety of ways:

  • Drill
  • Cutting / Sanding
  • Polishing

What is the pot life?

The period of time in which the epoxy resin can be processed is called the "pot life". It depends on various factors: 

  • Resin used
  • Processing quantity
  • Ambient and surface temperature
  • Epoxy resin temperature 

In the pot life, the viscosity changes from thin to thick, until it can no longer be processed . Depending on the amount used and the external factors, there is little time left for processing after mixing the epoxy resin. It is therefore worth mixing only as much as can be processed. 

Get bubble free epoxy resin

  • The containers should not be shaken before the epoxy resin is actually mixed
  • The epoxy resin and the hardener can be placed in a warm water bath beforehand
  • When mixing, you should mix calmly and regularly so as not to incorporate too many air bubbles.
  • If you pour objects, seal them in advance with epoxy so that no air bubbles can escape during the pouring process
  • In cases of hardship, a vacuum pump can also be used to remove air bubbles

We constantly update this article to provide impartial, informative, simple to read, and accurate information, to stay up-to-date, please visit this article regularly.