orks of art made from the durable and stylish material known as epoxy resin are a popular DIY project, despite the great amount of effort involved in creating such a piece. Once your resin item has been cured and hardened completely, you may notice that the piece possesses an uneven, cloudy finish that is nothing like the glossy surface for which this material is famous. This article will inform you as to the best techniques and tips on how to sand epoxy resin so that you can give your epoxy piece the sheen it deserves!
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Is it Better to Sand Epoxy Resin Dry or Wet?
When learning how to sand epoxy resin, you may be tempted to pick up a dry piece of sandpaper. However, we strongly recommend that you wet sand epoxy as opposed to dry sanding. There are a number of reasons why wet sanding is the best choice:
- Waterproof sandpaper tends to last longer when wet sanding than normal sandpaper in dry sanding.
- This technique removes smaller uneven areas straight away.
- The moisture of the sandpaper allows for less dust to be produced.
- As the dust collects in the water, you will be able to see the surface you are sanding more clearly, thus giving you an accurate gauge as to the progress you have made.
There are some instances, however, in which dry sanding resin is the more suitable option:
- Dry sanding is recommended for resin pieces that contain wood or other materials that are susceptible to the effects of moisture.
- Wet sanding can cause stains and may even result in the wood developing an odor.
In most cases, wet sanding is the most appropriate choice for sanding epoxy resin. We have found that dry sanding your resin piece will usually cause more harm than good:
- Dry sanding your piece with a random orbital sander, or even by hand, creates a lot of heat due to the friction between the two surfaces. Resin is resistant to heat only up to a degree, and if it gets too hot the surface becomes loose and will develop an unsightly matte finish.
- The scratched, matte surface of the resin as a result is nearly impossible to reverse. Wet sanding produces much less heat, making it the safer choice to protect the finish of your piece.
- Dry sanding produces a great deal more dust that is blown into the air. Not only are these particles carcinogenic, but they will cover the surface of your piece and make it difficult to ascertain your progress. If you are dry sanding, we recommend wearing a breathing mask for your protection.
Potential Complications of Sanding Resin
Epoxy resin is comprised of two components: a liquid resin and a hardener, also in a liquid form. When these two liquids are mixed together, the chemical reaction that ensues results in the solution hardening to become a solid. The epoxy resin will reach its most solid and durable state once it has cured for an appropriate length of time.
The hardened surface of this material means that it can be quite difficult to sand epoxy resin. This is especially so when the resin surface is dry, as the coarseness of the sanding paper against the tough resin surface means that it is worn down quickly. You will therefore need to clean or replace the sanding paper relatively often. You can reduce the amount of sandpaper you use by wet sanding the resin instead.
You should never sand your epoxy item until has been completely cured. This process takes a minimum of 48 hours after casting your resin, although you can see the manufacturer’s guidelines to get a more specific curing period.
A Guide to Wet Sanding Epoxy Resin
Most of the time, wet sanding resin is the best choice for smoothing and evening out the surface of your piece. We have compiled a useful guide on how to sand epoxy resin with water-resistant sandpaper.
Features of Water-Resistant Sandpaper
In order to begin the process of wet sanding epoxy resin, you will need a particular kind of sandpaper that is resistant to water. Comprised of a silicon carbide layer, this waterproof sandpaper is available from a minimum of 60-grit to a maximum of 4000-grit. The coarser grits are not advised for sanding resin, as they will leave behind scratches that can be hard to remove.
We recommend beginning with a 120-grit piece of sandpaper for your epoxy resin, and then gradually increasing this grit to one that is finer. You can apply an epoxy polishing paste to your sanded item at the end to give it a glossier finish.
Important Information About Wet Sanding Epoxy Resin
You may wonder whether you can sand epoxy with a machine or if it should be done by hand. We suggest that you wet sand your resin piece by hand, as using a machine can result in an electric shock if it comes into contact with the water. If you are working on an especially large surface, you can use an air disc sander, as these work on compressed air.
You can use a hard rubber sanding block to help you in the process of wet sanding. Using this block will help you to control the sandpaper for smoother, more controlled movements. Curved surfaces will require you to use an appropriate backing. Alternatively, you can hold the sandpaper yourself.
Water-resistant sandpaper tends to be quite stiff and tough to manipulate. The rigidity of the sandpaper can prove to be an issue when you are wanting to sand awkward areas and irregular shapes. You can get around this difficulty by using a waterproof sanding pad to reach these tougher spots.
Keep a relatively large amount of water nearby while you work. You can also use hot water if the room temperature is significantly cold, as the resin is sensitive to temperature. It is important to wet sand in circular movements, frequently dipping the sanding paper into the nearby water. You should only switch to a finer grit once the previous grit has been completely removed from the surface of the resin.
You do not need to fully-immerse the sandpaper in order to wet it sufficiently. You can even fill a spray bottle with water to frequently spritz and moisten the sandpaper surface.
The surface water will retain all dust residue, so it is important to wipe this away regularly. By doing this, you will be able to see the surface of your piece and how much progress you have made with regards to sanding. You should ensure that you clean the surface of the resin properly before switching to a finer grit, as the old, rougher grains of the old sandpaper can create scratches.
Once you have finished sanding your piece, you can use a paper towel to dry the surface. Any loose particles left behind can be wiped away with this towel or swept off with a fine brush. Do not use a cloth for drying the surface, as this can create unwanted streaks. You can use an electrostatic dust cloth to remove the finest dust particles if you are planning on painting your piece after sanding.
Tip: Use a paper towel to wipe away any leftover sanding residue immediately after you have finished the sanding process. Once the surface has dried, it is much more difficult to remove these grains from the resin surface.
Dry Sanding Resin
Dry sanding requires less time and effort when used over larger resin surfaces, such as tables. This technique is the most appropriate for sanding resin that has been used with wood, as materials such as wood are porous and absorb water more easily. If you choose to dry sand, we recommend using a random orbit sander.
- Before you begin dry sanding your project, ensure that you are wearing a protective face mask to prevent the inhalation of the many harmful dust particles produced as a result. Work in a well-ventilated area for further protection.
- You should begin with a coarser grain of sandpaper of 200-grit and slowly increase this grit to a finer grain of 1000-grit or higher.
- Dry sanding often results in the paper becoming dull quickly due to the abrasion of the dust. You can clean the sandpaper with a specialized rubber stick to make it last longer.
- You need to ensure that all sanding marks have been removed completely before adjusting the grit of your sandpaper.
Tip: You can only achieve a perfect glossy finish by using a fine piece of sandpaper of at least 1000-grit. Coarser grits cannot reach this level of shine.
What is Amine Blush?
Once your epoxy resin has hardened, you may notice that a sticky, wax-like layer has formed on the surface of your resin piece. This phenomenon is known as amine blush and is caused by major changes in temperature during the curing period. This layer can be difficult to see sometimes, as its appearance is liable to change.
You are most likely to notice an amine blush layer in extreme temperatures as a cloudy, greasy layer upon the surface of the resin. The resin surface beneath the amine redness is usually unaffected by this waxy layer, although it is worth removing so as to ease the sanding process.
Removing Amine Blush
While a layer of amine blush is unlikely to have an effect on the surface of your cured resin, it is best to remove in order to stop the sandpaper from dulling too quickly. Additionally, this layer cannot be present if you are planning on coating your piece with laminate resin or paint, as the coat will not be able to bind to the resin surface effectively. You can remove amine blush from your resin surface with the following:
- You can remove this layer with considerable ease by scrubbing it with some warm water, soap, and a sponge.
- Spirits can be applied to more stubborn waxy layers with a cloth.
- You can also remove amine blush by wet sanding the surface.
Sanding epoxy resin is often done when finishing off a casting. This can provide the perfect smooth shone to the end result – but if done incorrectly it could leave unwanted marks and textures. Be sure to follow the guide above for sanding resin to achieve perfect results every time.