Will Epoxy Stick to Cured Epoxy?

A question that is frequently asked in relation to epoxy finishes is whether or not it is possible to apply a new or additional coating to an existing one. The reason this query often arises is that using an epoxy coating involves a fair degree of preparation and for the epoxy coating to be created, two separate solutions need to be mixed.

There are also considerations in terms of setting and drying time.

The simple answer to the question is, ‘Yes,’ however, it does not apply in all circumstances, and there are several caveats which you need to be aware of.

So, before you go rushing off to buy epoxy solutions, please read on, so that you have all the facts.

Reasons Why You Might Want to Coat Existing Epoxy

There are many reasons why you would use an epoxy coating on flooring, especially in buildings such as workshops and garages. 

They’re tough and durable, so they are less likely to be damaged from dropped items or spillages. Epoxy floor coverings are also easier on the eye due to their smooth finish.

However, they are not indestructible nor are they always applied 100% correctly.

Damage

Epoxy coating are tough but there may come a point where even it cannot withstand a heavy object falling on the floor. If damage does occur then in order to repair it or to strengthen your flooring against further damage, you could apply a second epoxy coating.

Application mistakes

Another reason for applying an additional coat of epoxy coating is to fix a mistake that may have occurred during the application of the first coat. Below is a list of the more common problems which can occur, causing issues such as color differences, bubbles appearing, delamination, and circles appearing, known as ‘fisheyes,’ and poor adhesion.

• Poor preparation
• Stretching the epoxy out due to miscalculation of the amount required
• Issues with humidity or temperature
• Incorrect mixing
• Moisture being present in the concrete when applying the coating

Thickening

A very simple reason to add second and subsequent levels of epoxy coating is to thicken the surface and build it up further.  This will be a consideration if your flooring often has heavy equipment being moved or driven over it, if it is exposed to more chemicals than normal, and in scenarios where the concrete underneath is prone to cracking.

Scenarios Where You Can’t Apply a Second Coat

There are some situations where merely applying a second coat of epoxy is not possible, and so you will need to completely start from scratch.

One of these scenarios is where the existing epoxy coating has started to delaminate or is peeling. These indicate that there is a more serious problem to deal with which applying a second coat will not resolve.

Another scenario is when the existing coating is very worn and there is more concrete visible than coating. If you have painted over an existing epoxy coating or applied any other type of floor sealant then a second coat will not work as it will not bond properly.

In order to proceed in any of these cases just highlighted, you need to grind the entire coating away, and effectively apply a new first epoxy coating. In doing so, you need to follow all the preparation steps as you would for a new coating, including cleaning the surface and ensuring it is dust free.

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Preparing to Apply a Second Coat to an Existing Epoxy Coating

The key to making sure that the new epoxy coating you are applying to the existing one bonds and sets successfully is preparation. The first step in this process is to roughen the surface of the existing epoxy coating so that it is more conducive to the second one adhering to it.

A power sander is ideal for this, but it can also be done using a sander pole. Bear in mind you are only trying to de-gloss the surface and not remove it, so do not get too rough with it.

Once the surface has been sanded you need to sweep away the dust, and then thoroughly vacuum the surface. It is vital that all dust particles are removed, so there is a further step you should take.

Pour some methylated spirit onto a clean rag or towel and then proceed to wipe across the entire floor surface. This might seem like a lot of work, but it be worth it, as it will ensure that all the dust particles are removed.

The other benefit of methylated spirit is it evaporates quickly, so you will not have to wait until the floor dries, as you would if wiping it with warm water.

Once you have fully prepped the existing coat, you can proceed with mixing and applying the new coat as per the instructions on the specific epoxy coating brand you are using.