What Is Amine Blush And How To Prevent It
A lot of time, effort and investment can go into creating your epoxy resin art projects, which is why it can be devastating to learn your finished product has been tarnished by a chemical reaction you’ve never heard of before.
Unfortunately, this is what many beginners find with amine blush.
To help you better prepare for this potential defect on the surface of your next project(s), our team at Just Resin has compiled some information surrounding what amine blush on resin is, how it is caused, how to remove amine blush, and how to prevent amine blush it in the future.
What is Amine Blush & How Is It Caused?
Amine blush is a defect that can arise on the surface of your epoxy resin art project, affecting both the aesthetic appeal and physical integrity of the piece. It is a relatively common effect, as it can be caused by an array of different factors.
Generally, the curing agents known as ‘amines’ within the epoxy resin will undergo a specific chemical reaction as the hardener element interacts with higher amounts of moisture and carbon dioxide in the air itself. Without being overly technical, the amines will form what is known as a carbamate, which is the ‘blush’ or waxy film coating sections of the cured resin’s surface. Depending on the amount of moisture present, its effect will vary, but typically holds a cloudy, white colour, or turns a dirty yellow hue and appears like smaller grains of salt or crystals.
While this can be hard to avoid when using solvent-free epoxy resin, amine blush typically occurs when the epoxy is not permitted to cure in the proper, ventilated and temperature-controlled environment, prompting the chemical reaction. There is, however, also the risk of contamination on the surface of the epoxy that may cause a similar effect, including some oils and greases.
Is Amine Blush the Same as Amine Bloom?
While both amine blush and amine bloom can occur at the same time, the two defects are slightly different. Amine blush on resin will occur from humidity condensing the epoxy resin coating during the curing process. Amine bloom, however, occurs when moisture is drawn or ‘leached’ from the material of the
item or object upon which the epoxy resin has been coated, such as paint, leaving sticky, discoloured deposits on the surface.
What Effect Will Amine Blush Have on My Project?
As mentioned above, amine blush can create varying aesthetic damage to your projects, sometimes not entirely noticeable until you have completed the process. While you might be able to live with the soft white film caused by the blush, it is also important to understand the various effects it will trigger on the makeup of your project.
Amine blush on resin is known to prevent a range of varnishes, additional coats of epoxy and other substrates from successfully curing. This can also lead to the detachment of both the primer and finish, creating further defects and potentially ruining your project entirely.
Fortunately, there are easy methods you can take to remove amine blush from your projects as soon as they start to show to minimise their potential impact.
How to Remove Amine Blush
Given that amine blush is a water-soluble defect, amine blush removal should be relatively simple when utilising the correct tools. Gather a spray bottle of warm, soapy water and a stiff cleaning brush. Spray a generous amount of water over the area and begin scrubbing or moving the brush in a gentle sanding motion. It may take a bit of elbow work, but you will soon see the film begin to subside, and after wiping it away with a clean cloth or some paper towel, it will be all gone.
You may initially want to use more aggressive solvents to break down the blush, such as acetone, but these alone will not prove effective for amine blush removal, so it is preferable to just use the warm water and the brush.
Once the amine blush has been removed you can then sand or polish the surface and restore that flawless glossy surface.
How to Prevent Amine Blush
Prevention is always better than having to fix the problem, and given the information described above, if you are going to embark on a new epoxy resin art project, it is important to know how to prevent amine blush.
While your epoxy coating system will likely be able to withstand a moderate degree of moisture before amine blush occurs, there are two main precautions to take to prevent the adver
se reaction from happening, including:
When the relative humidity exceeds 80%, the surface of the cured product will absorb moisture and the finish may not appear to be glass-like. Amine blush can be washed away with warm soapy water and a sponge. If this doesn’t get rid of the amine blushing, you can sand and polish the surface or alternatively top coat. If all else fails, try using a flame torch and lightly waving this over the piece, being careful not to scorch the surface as this may result in irreversible damage. If amine blushing is proving a constant struggle, consider investing in industrial dehumidifiers or hot-air blowers to better control the humidity of the space.
When the temperature drops sharply, dew can form on a range of materials & surfaces. Should this happen to your substrate during the curing process, the new condensate (moisture) will adversely react with the amines and result in blushing or blooming. As such, take care to keep the temperature of the substrate to be at least 3 °C to 5 °C above the dew point (i.e. the temperature air needs to be cooled to meet humidity of 100%).