Which Epoxy Resin should I use?
Anyone visiting our website for the first time will realise right away that we have a vast range of materials to choose from and we also have a good range within each category. For example, we have over 10 types of polyester resins, over 15 types of cloths and around half a dozen brands of epoxy.
Let’s look at epoxies and hopefully the following information will help you choose the right one for your application.
Basically, I would say that any of the above brands will do for most General purpose applications and choice will just come down to which brand you are familiar and comfortable with, Price, kit size available or curing speed you require. But to help you with your decision should you wish to switch from a usual brand or you are a first time user, we have put this guide together to assist you.
At the moment the general lay-up epoxies are:-
West System epoxies
Sicomen SR Greenpoxy 33
SR5550 Multi-purpose epoxy resin (Fast)
These are marine-grade epoxies that bond and coat fibreglass, wood, metal, fabrics and other composite materials to provide superior strength and moisture resistance.
Also we have other epoxies such as:
Infusion Epoxy Resin EC157
Surf Clear EVO Epoxy Resin
ECF Art
ECF Clear coating
Sicomin Hi Temperature
SR Greencast Clear Epoxy Resin
But these are pretty much project specific so well come back to these later
Between the brands I wouldn’t recommend either one over the other in terms of performance, so if you want a general purpose epoxy you can use either West System, SR5550 fast or SR greenpoxy33.
West System:
A lot of epoxy users especially Boat repairers are most likely to use and recommend West System but this does not mean that it is necessarily the best one to choose, It tends to be the most recognised and popular one due to the fact that West System have put in a lot of work to promote the product and they have a vast range of products and guides.
The project information west system put out there on the internet is excellent and you can almost always find a guide or even a YouTube tutorial based on your Epoxy project using west system. Their website itself has lots of useful guides and product information. (See link below)
Here is another good source of information on using west system http://epoxyworks.com/
They certainly do not exaggerate when they claim ‘The WEST SYSTEM® range is a pioneer of all marine-grade epoxy systems’
Like most brands of epoxies West System have different curing speeds for their hardeners, we currently stock 205 fast and 206 slow hardeners.
The slow hardener combined with the 105 resin is the preferred option for larger projects such as stitch and tape canoe or boat building or if a longer curing time is required.
The Fast combined with the 105 resin tends to be used obviously where a faster setting is required , This may be used on smaller projects such as models or mixed with thickeners or other powders to produce bonding or fairing compound, for example bonding in woods or filling voids and surface repairs prior to sanding.
Fast hardeners are sometimes used when working temperatures are low too but do not use below 5 deg C or when moisture levels are high.
West system also do a special coating Hardener 207 which is often used for coating wood to enhance the wood grain and give a clearer coat, however do not confuse this with the version available in the USA which is known as clear coat as the US version is much clearer to that available in the UK.
Sicomin SR5550:
This is another good Brand of epoxy and is also good for marine composites, bonding, laminating and wood protection.
It has an excellent adhesion to all type of wood. It is Crystallization Free so unlike a lot of other epoxies it tends to store better in colder conditions without crystalizing. It is also UV Stable.
S-R5550 has 2 mix ratios for ease of use. 100:29 by weight is always more accurate but 100/33 by volume is also recommended if customer have no scales. This is also 3:1 by volume system.
This Product has been specifically designed for use on wood so is ideal for bonding reinforcement materials such as fibreglass or carbon onto wood.
Other Key advantages: -
• Suitable for room temperature applications
• Delivers a high gloss finish
• Low surface pollution, UV stable and low toxicity.
SR Greenpoxy 33:
This is a more economically priced epoxy, probably about the most economical as you can get with an epoxy as epoxies tend to be 3-4 times more expensive than polyesters, basically due to the chemical makeup of epoxies and the fact they will outperform most polyester resin systems
The only disadvantage I would say this product has compared to others brands is that there is not much out there in terms of marketing , online tutorial guides and customer feedback, making it less recognised and sought after amongst boat builders, boat repairers , hobbyists etc.
Other epoxy Systems: as mentioned earlier we have other epoxy resin systems but these are not classed as General purpose use and are project specific, the clue to their usage is in their name.
Infusion Epoxy Resin EC157 This is primarily for use only with the infusion process.
Successful laminates have been accomplished by hand using this resin however it is very temperature and mix ratio sensitive so avoid this if you are wanting to hand laminate or coat anything, stick to this only for infusion purposes use one of the afore mentioned epoxies for general hand lamination.
Surf Clear EVO Epoxy Resin Is great for surfboard skinning and has good viscosity for wetting out our surfboard fabrics. It has high temperature and UV stability and can also be used for surf repairs, fin boxes & plugs, pattern, and model coating, etc..
Sicomin Hi Temperature Epoxy Resin
Developed for high service temperature tooling from 120°C up to over 200°C
continuously depending on the chosen hardener. Excellent chemical resistance, resistance to oxidization, low exothermic peak. For laminating, press moulding, casting or injection. Application type: Composite tooling for “120°C” prepreg, thermoforming tooling, structural parts with a high service temperature.
Please see data sheets online for more detailed technical info.
Now for the Art epoxies:-
ECF Art available in fast, slow and medium
This is a good product for sealing most artworks or for doing very shallow casts such as coasters at around 4mm max in one cast or for very small pieces such as chess set pieces and jewellery. but for casting at this thickness, you really have to use the slow cure version, don’t try and use this one for deeper casts such as paperweights, pyramids etc as it gets too hot and cracks at those volumes.
ECF clear coating available in fast, slow and medium
This is pretty much the same product as the ECF ART however we market this towards coating products such as table tops etc however please be aware that this holds no food safe certificates so we wouldn’t recommend this on food preparation surfaces
SR Greencast Clear Epoxy Resin
This is the one we’d recommend for deep pour projects such as rivertables, paperweights etc. Is has a slow cure so it doesn’t get hot whilst curing and does not crack. I would recommend only using this in areas where you have shelter from the weather and have good constant room temperatures. Also allow for several days to a week for full cure. For example, if you use this for a Bar or restaurant counter top don’t expect to have it usable the very next day �� make arrangements to either close it off or covered whilst it cures for a week.
SR Greencast Clear Epoxy Resin is a totally clear epoxy resin system with enhanced UV resistance. Greencast epoxy resin is a 'eco-friendly' resin - with 37% of it's molecular structure coming from plant sources. It is ideal for casting and encapsulating, for bottle prototypes for jewellery and for river tables etc. Advantages of this system include room temperature curing, High clarity and good brightness, very low reactivity enabling deep pours up to 10cm.
37% of the molecular structure comes from plant-based carbon so the green credentials are excellent.
Other advantages: Low odour and reduced skin aggression for a better work environment.
Hopefully This Guide has assisted in helping you choose the right epoxy for your needs. As always, our tech advice team is always on hand on 0191 4975134 for further advice.
This advice and information is given in good faith for guidance only. and is given without warranty, users should determine information given and using their own judgment to determine suitability.
To reassure our customers - all materials supplied by East Coast Fibreglass Supplies are of the finest quality, manufactured by companies such as Scott Bader, DSM, Owens Corning, West System, Sicomen to name but a few, who all have supplied materials into the Composites industry for many years on a global scale. Samples from every batch manufactured are retained for testing, should the need arise.