EF80 Flexible Epoxy Resin

As with many post-cure cycles for resins, the post-cure cycle for our EL2 and IN2 Epoxy Resins is not too sensitive and a range of different post-cure cycles will produce good results, specifically improved mechanical performance and elevated HDT/operating temperature. Post-curing parts that will be used at or exposed to elevated operating temperatures (such as vehicle bonnets/hoods in direct sunlight, engine-bay parts, car interior parts etc.) is strongly recommended to prevent distortion of the parts when they are put into service and experience these higher temperatures.

Where possible, parts should be post-cured still inside the mould to reduce distortion and improve surface finish (i.e. reduce 'print-through'). When post-curing parts in the mould, it is important to post-cure them without demoulding at all (i.e. don’t demould and then put them back into the mould) otherwise you can get some strange patterns on the surface where some areas are post cured in direct contact with the mould surface and others are not.

A simple and very effective post-cure cycle with the IN2 Infusion Resin (or EL2 Epoxy Laminating Resin) is as follows:

CYCLE #1 SUITABLE FOR MOST SITUATIONS

1. 24hrs at room temperature
2. 6hrs at 60°C

If you’re encountering any surface finish issues (faint print-through) then you can experiment with a slower 'ramp rate' which sometimes improves things:

CYCLE #2 SUGGESTED FOR SUBTLE IMPROVEMENTS TO SURFACE FINISH

1. 24hrs at room temperature
2. 2hrs at 40°C
3. 2hrs at 50°C
4. 5hrs at 60°C

If you need to push the HDT of the finished part higher then you could increase post-cure up to a maximum of 80°C as follows:

CYCLE #3 SUGGESTED FOR HIGHEST POSSIBLE HDT/OPERATING TEMPERATURE

1. 24hrs at room temperature
2. 2hrs at 40°C
3. 2hrs at 50°C
4. 2hrs at 60°C
5. 2hrs at 70°C
6. 4hrs at 80°C

These are all just suggestions. Most situations just call for option #1; 6hrs at 60°C. Many customers also find that they can dispense with the 24hrs cure at ambient and simply load newly infused parts into the oven to begin the cure however this is something that you would need to experiment with yourself. A cure at ambient temperature before post-cure is generally favoured with most resin systems.

Yes, but it's highly recommended to use specialist 'powder bound' chopped strand matt. This is because conventional chopped strand matt is 'emulsion bound' which relies on styrene and solvents in the resin to break the binding down. Epoxy does not have these solvents. As a result, specialist 'powder bound' chopped strand matt is needed as the powder binding is broken down by the liquid itself.

Most cured epoxy resins have self-extinguishing properties however none of our epoxies have formal 'fire rating' data because they're not designed as intumescent or fire retardant resins. The reinforcement you use will also have an impact on the fire retardancy of the finished product.

If you're specifically setting out to make fire-retardant parts I would suggest using a specialist intumescent resin - however, bear in mind that generally these resins will contain inert fillers which compromise their mechanical performance to some extent.

No, we wouldn’t suggest Epoxy Resins for lining a fuel tank. In general, epoxies have good resistance to petrol and many of the chemicals and additives found within pump fuel however the ethanol in fuel is known to cause problems over time and so specialist tank lining resins (often novalac vinylester based) should be used instead. One such product is GTS 1750 which is sold by Caswell Europe.

No, this epoxy in common with other epoxies does not attack expanded polystyrene

We have not specifically saught FDA (or similar) approval for this resin system so if you were to make these plates commercially then you would either need to make a plate using this resin system and then have it tested and approved safe for food use or use a different resin system that has specifically been approved for food use. Mixed and cured fully and properly the resulting plastic should be stable and non-toxic but testing would be required to prove this. Regarding being dishwasher safe; a dishwasher is a very harsh environment (abrasive, high temperatures, caustic) and so I think it would be quite hard on any resin system. By all means conduct your own tests but I would strongly recommend that a carbon fibre plate was not marketed as 'dishwasher safe'.

Although generally cured epoxies are non-hazardous, none of the products we have are certified food safe and thus we cannot recommend their use with food products.

We recommend Acetone. The brushes must be cleaned before the resin has cured. If you can’t get hold of acetone it’s also possible to use methylated spirits or neat alcohol.

In really simple terms you can think of 1kg of the Epoxy Resin as being 1L. If you want to be really exact (for example if you want to mix the resin and the hardener by volume and not by weight (which we don't recommend because it's unnecessarily complicated) then the relative density of the resin and the hardener, and the mixed product, can be found on the technical datasheet.

We can send any quantity of resin to Portugal. We would use a TNT Road service. To find the shipping cost for any item, simply add it to your basket and then click the 'Estimate Shipping' button on the basket page. The price will then be shown once you chose your shipping country (Portugal).

Unlike other resin systems such as polyester or vinylester, it's very important to get the mix ratios accurate with epoxies. If you get the mix ratio wrong by a small amount (let's say a couple of grams on a small mix) then the resin will still cure but the mechanical properties won't be quite as good as they would have been if the mix ratio had been exactly right. However, if you were to be out by anything more than a few grams then you might find that the resin would not be properly hard when cured and/or may have a tackiness to the finish. This would result in a much weaker repair and needs to be avoided by careful measurements.

Above the HDT of a resin system it will soften slightly and its mechanical properties will start to fall away however a thermosetting plastic (like epoxy) is NOT a thermoformable plastic so it will not start to flow again such that you could melt it out of your part. It's more likely to become slightly soft and then possible more brittle again before eventually starting to burn if you too the temperature high enough. It sounds to me like you need a thermoformable plastic (aka a thermoplastic) with a relatively low melting point. I'd suggest something like PCL.

An elevated temperature post-cure is not required for parts made with epoxy resin however, post curing parts will improve the mechanical properties of the resin (and therefore the part) and so if you have the means to do it then it's certainly recommended. One major advantage to post-curing epoxy is that you will raise the HDT (heat distortion temperature) of the part meaning that it's less likely to soften or distort in higher temperatures. This can be particularly important for parts like a vehicle panel (i.e. hood/bonnet) which could get very hot in the sun. Without a post-cure there is a good chance that the part would effectively post-cure itself 'in situe' when it's in direct sunlight which can cause the resin to soften, sink and then re-harden. When this happens to a fitted part it's likely to distort the surface finish. A part that had been post-cured prior to installation would not have this problem.

Epoxy resins have very little odour and so it's quite viable to use them indoors (i.e. in your house) without upsetting anyone. The resin is almost completely odourless and the hardener has an amonia smell which doesn't really carry or linger.

In this respect epoxies are very different to polyester and vinylester resin which has a very strong smell and cannot realistically be used indoors. As always, you should still follow safety precautions and ensure adequate ventilation of your work area.

Uncured resins are classed as dangerous goods and would need to be disposed of correctly. For domestic users, usually your local council recycling centre will have a disposal service for such chemicals or containers.

Because cured resins are inert and safe for disposal it's often easiest to mix un-needed or out-of-date resin and hardener together to cure them. Once cured they can be disposed of with general waste.

Epoxy is sensitive to low temperatures so we would not attempt to try and cure the resin at very low temperatures such as below 15 °:C. At those temperatures, the cure time will be lengthened considerably.

One of the most significant problems caused by low temperatures (much below 20°C) is that the resin will be considerably thicker which affects its ability to self-degas after pouring.

Also, curing epoxies are hydroscopic so the low temperature environment may well leave the resin vulnerable to absorbing moisture, especially if the environment is relatively damp or high in humidity as can be found in some outdoor workshops or home garages.

As a result, for best results we always recommend working in an environment that is 20°C or above.

The B stage of the cure is when the resin has cured enough to be firm but still tacky. When touching with a gloved finger, the resin should feel tacky but not leave any residue on the glove.

Our EF80, like most modern epoxies, has a good resistance to UV due to UV inhibiting additives. However it is not totally UV stable and as such will over a period of time, eventually degrade due to UV exposure. This normally takes the form of yellowing of the resin which depending on the resin layer thickness and base colour of the fabric may take many years to become noticeable. The EF80 already has a slight amber tint to it. In terms of protection with clear coats, the EF80 is a very flexible resin and as such most clear coats would not adhere to or would crack up and flake very quickly when used on this resin.

EF80 is not really intended for cosmetic applications and so I would be quite wary about adding translucent tinting pigments if you wanted/needed the cured laminate to have a specific colour and also hold this colour over time. As well as the background yellow tinge to the EF80 there would also be UV stability to consider where it's likely that EF80, with or without a colour tint, would discolour over time. If it's for a short-term application or not likely to be exposed to much UV light then you could potentially tint it but for long-term colour-fast cosmetic applications I wouldn't recommend it.

In terms of the effect of the 'straw' colour on the tints, if you did use them, I would think it would only really be an issue if you were using very subtle amounts of tint. Any stronger amount of colour would over-ride the background colour of the EF80.

There is not really a minimum thickness that EF80 will cure at. We have successfully used it as a brush-applied thin film and it has cured fine at this thickness.

No. Our EF80 would not be suitable for this application. The resin system is designed for its flexible, structural property, it's not designed as a UV stable coating. For an external, UV exposed coating application like this we would normally suggest our our XCR Epoxy Coating Resin. However, if you specifically need a flexible coating then we don't currently have a suitable product.

Once cured, EF80 is basically stable and inert. Although we don't have any empirical test-data for gas permeability or water absorption, both of these values should be negligibly small and so in practical terms it would be appropriate think of the cured resin as impermeable to gas and water.

We would not recommend mixing two different epoxies. Almost all different epoxies are likely to have a different blend of ingredients so adding one epoxy to another is likely to cause curing problems for the mixture as a whole.

Our EF80 is a very flexible resin so would offer no rigidity and very little spring effect if used in that way so this would definitely not be the right resin for this application.

However, our Epoxy Rapid Repair Resin is a high performance, rigid structural resin with a high flexural strength and a high bond strength and so would be ideal for applications where bending loads are to be experienced.

I think the only 'gelcoat' that could realistically be used with a flexible resin like the EF80 would be a gelcoat made using the EF80 itself. To do this, you would add some Fumed Silica to the EF80 (mix it in very thoroughly) until it has the thixotropic properties of a gelcoat. You could also use epoxy colour pigments to pigment the resin/gelcoat.

The EF80 is very flexible so would certainly mean the arch extensions would flex well under impact. Depending on the shape and curvature, you may need to vary the number of layers of reinforcement you use to achieve enough stiffness for the shape to be self supporting as the resin itself will add only a very small amount of stiffness to the laminate.

Our EF80 cures transparent with a light amber tint

The degree of flexibility is determined by the number of layers as well as the shape of the finished laminate. For example a single layer of Carbon Fibre 2/2 Twill 3k 210g laminated with EF80 can be easily bent back on itself. As you add more layers then the reinforcement will start to stiffen the laminate, although the resin matrix does remain flexible.

No; our EF80 is too flexible for making rigid items like kayak hulls. If you need a really impact resistant kayak hull we would suggest using a standard rigid epoxy resin like our EL2 Epoxy Laminating Resin (if you’re hand laminating) or our IN2 Epoxy Infusion Resin (if you’re going to infuse the hull). You could then achieve the impact strength you need by making extensive use of an impact resistant reinforcement such as our 300g 2/2 Twill Aramid Fibre or 300g Plain Weave Diolen.

No, once fully cured, the flexibility of the resin will always be the same. You cannot change the flexibility/hardness by varying the cure temperature.