Sanding epoxy resin between coats is essential for achieving a flawless, professional-looking finish in your resin projects. Whether you're working on a piece of art, furniture, or a countertop, understanding how to properly sand resin can significantly affect the final outcome. In this article, we'll explore the importance of sanding epoxy resin between coats and share tips for avoiding common pitfalls.
What Is Sanding For?
Sanding is essential for several reasons when working with epoxy resin. It removes imperfections such as bubbles, hair, or dust from the resin surface. Sanding also ensures adhesion between coats of resin by roughing up the smooth surface, creating tooth for the fresh epoxy layer to adhere to. Additionally, sanding can be done after a resin project cures to remove sharp edges. Best practices for sanding include wearing a protective mask to prevent inhaling fine resin dust, using a coarse sandpaper (such as 80 grit), and thoroughly removing all trace of sanding dust before applying a fresh coat of epoxy resin.
What Happens If You Don't Sand Between Coats Of Epoxy?
If you don't sand between coats of epoxy, several issues can arise:
- Visible Imperfections: Any imperfections or bubbles in the previous coat will remain and may even become more noticeable in the final finish.
- Poor Adhesion: The next layer of epoxy may not adhere properly to the previous one. Sanding creates a rough surface that helps the new layer bond effectively.
- Delamination: Over time, the layers might separate or peel away from each other, compromising the durability and integrity of the piece.
Can I Apply Second/Multiple Coats Of Epoxy Resin?
Yes, you can apply a second coat of resin if you need to fix a mistake or a surface imperfection. You can also pour multiple layers if you need to cover areas of high relief, if you're pouring into a mold or if you simply like the look of a thicker coat.
It's important to remember that the ideal ArtResin pour is 1/8" or 3 mm. If you pour thicker than this, bubbles may not be able to escape and will end up curing in your resin. A better approach is to layer ArtResin in multiple coats: you can layer as many coats as you'd like, as long as you pour in 1/8" or 3 mm increments.
How To Apply A Second Coat Of Epoxy Resin:
Most people who do a second coat of epoxy are trying to fix a surface imperfection that happened in the first coat. For example, you may find bubbles, or hair or dust that landed while your piece was wet and cured into your resin.
1. What grit to sand epoxy between coats
First, if your previous mistake includes uncured resin, it's important to scrape off as much sticky material as you can and discard it. Next, sand down all the cured areas of your piece with coarse sandpaper (we use 80 grit sandpaper here at ArtResin). Sanding epoxy resin between coats will not only remove the imperfection, but will also provide some tooth for the second epoxy layer to adhere to.
It will look very scuffed in the short term, but don't worry, once you pour the second coat over top, all of those sanding marks will disappear.
2. Clean sanding dust & pour the next coat
Wipe away sanding debris very well. You may want to wipe with a damp cloth, brush with a soft brush, or spray with a can of condensed air to make sure there are no traces of sanding residue left. Once the surface is completely clean and dry, then pour your next coat of accurately measured and mixed resin on top. Last, cover with a dustcover to make sure you avoid any of those imperfections a second time and you should be good to go.
💡 TIP: ArtResin self-levels at about an 1/8" or 3 mm. You can pour a little deeper if you're pouring into a vessel like a silicone mold, but you want to be careful not to pour deeper than 1/4" or 6 mm for a couple of reasons: first, it's hard for bubbles to release at anything thicker than this and second, the resin can heat up and cure prematurely if you pour too thick.
How Long To Wait Between Second or Multiple Coats Of Epoxy Resin:
Some artists like to do multiple coats with acrylic paint or artwork in between each layer for a 3D effect. You can also pour multiple layers of ArtResin if you just like the look of a thicker coat, if you want to embed objects into the resin or if you're pouring into a silicone mold.
If you're looking for that layered look, there are two ways to achieve it:
1. Wait 24 hours, sand and pour
The first method is to wait 24 hrs after your first pour, then sand down the whole piece with coarse sandpaper to create some tooth. Wipe clean and pour your second coat at that point, as originally described. Repeat until you reach the thickness you desire.
2. Wait 3-5 hours and pour
To save you some time, the second method is to wait 3-5 hrs after your first pour, until the resin has reached a gel state. Instead of sanding, you'll pour the second coat directly on top of the curing resin. The stickiness of the resin will provide the tooth and the curing will happen simultaneously between the two layers, bonding them together very nicely. Repeat these steps until you reach the thickness you desire.
Both methods work very nicely for pouring multiple layers! So whether you're working on an epic piece with lots of layers, or you're simply trying to fix an imperfection on your first coat, rest assured that pouring a second coat is always an option!
Key Mistakes to Avoid When Sanding Epoxy Resin
Avoid these common mistakes to achieve a perfect result:
- Starting with Sandpaper That's Too Fine: Use coarse grit sandpaper to rough up the resin, creating enough tooth for the fresh resin to bond.
- Not Sanding Deep Enough: Ensure you sand deep enough to remove imperfections, especially bubbles.
- Sanding Too Deep: Avoid sanding so deep that you damage the artwork below.
- Not Removing Sanding Dust: Thoroughly wipe away all sanding dust and residue, particularly from nooks, crannies, or bubble holes. A soft toothbrush or compressed air can help to prevent trapped dust in your resin cure.
- Skipping Grit Levels: When sanding to create a matte finish, ensure you gradually move your way up through the different grit levels to achieve a smooth finish.
By avoiding these mistakes and using proper techniques, you'll be able to fix mistakes, build up layers, or create a matte finish for beautiful and durable epoxy resin projects!
Essential Safety Tips for Sanding Epoxy Resin
Safety should always be a top priority when sanding epoxy resin. Here are some essential tips to ensure your well-being and the environment:
- Personal Protective Equipment (PPE):
- Respiratory Protection: Wear a mask or respirator to protect yourself from inhaling fine dust particles.
- Eye Protection: Equip safety goggles to shield your eyes from hazardous particles and debris.
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Skin Protection: Cover up with long sleeves and gloves to prevent skin irritation.
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Ventilation: Work in an area with excellent ventilation to disperse airborne particles. Even better, vacuum up dust with a system fitted with a HEPA filter to capture fine epoxy particulates.
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Wet Sanding Technique: Opt for wet sanding whenever possible to reduce dust emission. Allow the resin to thoroughly dry before applying a fresh coat.
By following these best practices, you'll fix imperfections or achieve a thick coat of resin with an impeccable finish!
Learn more about surface preparation before using epoxy resin. Read our guides below:
Can I Resin Over A Curved Surface?
What Is The Best Supportive Surface To Use With ArtResin?
Can I Get A Textured Surface With Epoxy Resin?
What’s The Best Surface To Use With Epoxy Resin?
Where Should I Epoxy Resin My Work?
Surface Preparation Before Applying Epoxy Resin
Can You Spot Fix Small Imperfections in your Epoxy Resin?
Will I See Scratch Marks From Sanding Under A Second Coat Of Resin?
ArtResin: The Original Epoxy For Resin Art.
