This post may contain affiliate links. We may earn a small commission from purchases made through them, at no additional cost to you. Show
For the perfect glass-like surface on your epoxy resin work piece, sanding after curing is essential. In the following article we will explain which material you need for epoxy resin sanding and what you should pay attention to. In addition, you will receive step-by-step instructions on how to best proceed when sanding a resin surface. Table of Contents
Difficulties when sanding epoxy resinCasting resin becomes an extremely hard material during curing. Therefore it can be a real challenge to sand the dried workpiece afterwards. The reason: the abrasive paper becomes dull very quickly due to the hardness of the material. In addition, it often happens that the sandpaper has to be cleaned or even replaced completely after a short time because the hardened resin adds to it relatively quickly. In order to reduce the clogging considerably and thus to be able to use the paper for a longer period of time, we recommend wet sanding.
Wet or dry sanding?In our experience, wet sanding of epoxy resin with waterproof sandpaper has clearly proven to be more effective than dry sanding. And there are several reasons for this. Firstly, the abrasive paper is much less clogged during wet sanding and therefore lasts much longer. Small irregularities are removed directly during the sanding process and you can immediately see the later result. In addition, the amount of dust produced is much lower. However, there are also cases where dry sanding is more suitable. This is the case, for example, if you want to combine your epoxy resin piece with wood or other materials that are sensitive to moisture. Wet sanding would cause the wood to swell and leave unsightly stains. But there are also other reasons why wet sanding is generally more suitable than dry sanding. One of these reasons is that dry epoxy resin sanding, whether with a random orbital sander or by hand, generates extremely high heat. This heat may cause the resin to dissolve and the surface to become matt. It is almost impossible to give the surface a beautiful shine again in this case. Since the temperature point can vary greatly depending on the casting resin used, you should opt for wet sanding in case of doubt to be on the safe side. Because this produces considerably less heat. In addition, dry sanding of epoxy resin produces a lot of dust. If you decide to use this method, you should always make sure to wear a mask, as epoxy resin dust is considered carcinogenic. Pros
Cons
Waterproof sandpaper – what is it?For wet sanding of epoxy resin you need waterproof sandpaper. This consists of a closed layer of silicon carbide. This paper is available in grit sizes from 60 to 1000. However, as too little grain can cause deep scratches in the surface, you should start with a grain of 120 or more for your epoxy resin piece. The damage caused by scratches can only be repaired with great patience and with great difficulty. If you want to achieve a nice shine on the surface of the resin, you should sand your piece of art up to a grain size of 3000. After sanding use polishing compound and a polishing machine for polishing the epoxy resin surface.
View on Amazon
View on Amazon Wet sanding of epoxy resin – Step by step guideAs a rule, wet sanding of cast resin is carried out by hand. For your own safety, do not use an electric sanding machine for this method. Since water is used, the risk of suffering an electric shock is simply too high. However, an air-powered sander is a good alternative if you want to work on a large surface. To keep the abrasive paper smooth during wet sanding, we recommend a hard rubber sanding block. If the surface is curved, it may be necessary to use a suitable backing. As an alternative to an underlay or block, you can simply place the abrasive paper in your hand and then dip it in water. Unfortunately waterproof sandpaper is relatively rigid and inflexible. This can be a problem if you want to work on structured or very irregular surfaces such as a sculpture. Here the paper does not adapt sufficiently to the existing curves. For these cases we recommend a sanding pad, e.g. the 3M Scotch Brite. This is much more flexible than sandpaper and can also be used wet.
View on Amazon
Dry sanding of epoxy resinWhen sanding larger surfaces, dry sanding of the resin is much easier than wet sanding. You should also use this method if you want to process additional wood. For dry sanding we recommend the use of an orbital sander.
View on Amazon
View on Amazon Amine redness – a waxy layer on the resinYou may notice that a waxy, slightly sticky layer forms on the surface of your work piece during the curing process. This so-called amine reddening occurs especially with fluctuating temperatures during the drying process. Since its appearance can change, it is sometimes difficult to see it at all. At cool, humid temperatures it is relatively clear as a thin, greasy or dull layer that can be seen and felt. The casting resin under this layer is usually undamaged. Nevertheless, you should remove the amine blush, as normal sandpaper would immediately clog up due to the waxy, sticky surface. Here are some tips to remove the amine blush as quickly as possible:
Why you should remove amine blushThe amine blush itself does not pose a problem, as it does not damage the casting resin. However, if you want to further process your workpiece, e.g. with an additional epoxy coating or a lacquer, it is essential to clean the surface in advance if amine blush has formed on it. Otherwise, these substances cannot bond effectively with the resin. What is the best sandpaper for epoxy resin?Waterproof Sandpaper
Grits from 60 to 1000 are available, although you should only need 60 to 80 grit for initial abrasion, and 180 to 220 grit or maybe 320 for final sanding prior to priming or varnish. If your cured epoxy has runs and irregularities, I suggest starting with 60 or 80 grit sandpaper.
How do you sand epoxy and make it look clear?Getting Started – Sanding of Epoxy Resin
Use a wet sanding sandpaper. This wet standing technique involves carefully sanding from grit 120 to grit 1500. This work can be done by your hands or special tools like electric sander. Keep in mind, to always clear these away before you start polishing!
What should you sand resin with?For wet sanding of epoxy resin you need waterproof sandpaper. This consists of a closed layer of silicon carbide. This paper is available in grit sizes from 60 to 1000. However, as too little grain can cause deep scratches in the surface, you should start with a grain of 120 or more for your epoxy resin piece.
|