How Do You Waterproof Clay Coasters?

Waterproofing clay coasters is an important step to help protect your surfaces and extend the life of your handcrafted ceramic pieces. Unglazed clay is porous and will absorb liquids, leaving rings, stains, or moisture damage over time. Waterproofing forms a protective barrier that prevents this absorption. It allows you to fully enjoy using your artistic clay coasters without worry of ruining them or your furniture from condensation rings, drips, or spills.

This guide will walk through the simple process of waterproofing oven-baked clay coasters using liquid sealers. With just a few basic supplies and some easy steps, you can add a water-resistant finish to your unglazed clay coasters. The sealers soak deep into the clay to seal the pores and create a lasting waterproof barrier. Your coasters will be able to withstand moisture while keeping their natural clay look and feel. Let’s get started!

Materials Needed

To make waterproof clay coasters, you will need the following materials:

• Clear acrylic sealer – This provides a protective coating over the clay. Choose a sealer specifically made for polymer clay.

• Polymer clay – Use an oven-bake clay in your preferred color(s). Sculpey and Fimo are common brands.

• Baking trays – You’ll need a smooth baking tray or tile to bake the clay coasters on.

• Oven – For baking the clay according to package directions.

• Paint brushes – Small brushes to apply the acrylic sealer.

Make sure you have all materials on hand before starting the project.

Shape and Bake the Clay

When making clay coasters, you’ll first want to shape the clay into the desired form. Clay is very malleable, so you can shape it by hand into round circles or squares for typical coaster shapes. You may also want to use cookie cutters, molds, stamps, or other tools to create fun shapes like stars, hearts, or custom designs.

Once you’ve shaped your clay coasters, you’ll need to bake them according to the clay manufacturer’s instructions. Every clay is a little different, but generally you’ll want to bake the clay at 275°F to 300°F for 15-30 minutes. Make sure to check on the clay towards the end of the baking time to ensure it doesn’t burn. The clay should be hardened but not too brittle after baking.

After baking, allow the clay coasters to cool completely before applying any finishing steps like sealing or decorating. The high heat from baking will solidify the clay so it can withstand water and use as functional coasters.

Prepare Workspace

Before starting the waterproofing process, it’s important to properly prepare your workspace. This will help ensure you can work efficiently and safely while sealing your clay coasters.

Be sure to cover your work surface with newspaper, cardboard, or disposable wax paper. Waterproofing sealers and finishes can stain furniture, countertops, and floors, so lay down a protective layer. Tape down the edges so the paper doesn’t slide around.

Wear latex or rubber gloves to protect your hands from repeated exposure to sealers. The chemicals can dry out and irritate skin over time.

Work in a well-ventilated area, preferably near an open window or outside. Sealers and finishes give off strong fumes, so you’ll want proper air circulation. Use fans to direct air flow away from you if working indoors.

Having a clean, covered, and ventilated workspace helps create the ideal set-up for safely and neatly sealing DIY clay coasters.

Apply Sealer Coats

Once your clay coasters have been shaped, baked, and cooled, they are ready for sealing. Sealing is a crucial step to making your coasters waterproof. When applying sealer, you’ll want to use thin, even coats and allow proper drying time between coats.

Start by preparing your workspace with newspaper or scrap paper to protect your surfaces. Using a soft paintbrush, gently brush on a thin layer of sealer completely covering the top and sides of the coaster. Let this dry for at least 1 hour. Once dry, add a second thin layer and let dry for another hour. For extra protection, a third thin coat can be applied after the second has dried.

It’s important that each coat is thin and dries fully before adding the next. Thick coats that pool or puddle can become sticky and take much longer to cure. Thinner, multiple coats provide a smooth, even seal that fully protects the clay.

Take care not to overbrush or scrub too aggressively when applying sealer. Soft, fluid strokes work best to prevent pulling up clay particles. Work in a dust-free area since specks in the sealer will affect the finish.

Once all coats have fully dried, the sealant will be water-resistant and ready for use. Be patient and allow the full recommended drying time between coats for best results.

Cure and Dry

After applying the sealant, it’s crucial to allow adequate time for curing and drying before using or washing the coasters. The curing process allows the sealer to fully saturate the clay and achieve maximum waterproofing ability. Drying time is also essential to ensure all solvents have evaporated from the sealer.

For best results, allow 72 hours for the coasters to fully cure and dry after the final sealant application. Place the coasters in a dust-free area with good air circulation. Avoid touching or using the coasters during this period. 72 hours allows all solvents to evaporate and the sealer to fully harden within the clay.

If impatient, it may be tempting to use the coasters sooner. However, doing so risks permanent damage. Insufficient curing and drying will likely result in loss of waterproofing, smudging, peeling, cracking, and other issues. Be patient and allow the full 72 hour cure time for optimal results.

Additional Decorations

Once your clay coasters are fully sealed and waterproofed, you can add some extra decorative touches if desired. Paint, glitter, gems, and more can help make your coasters unique. Here are some ideas for decorating sealed clay coasters:

Paint: Acrylic paint works well on sealed clay. Make sure to use craft paint that is designed for painting ceramics or clay. You can paint designs, patterns, names, monograms, flowers, animals, and more. Use a paintbrush or foam pouncer to add paint details. Let the paint fully dry before using the coasters.

Glitter: For sparkling coasters, you can apply glitter over sealed clay. Use a craft glue or decoupage medium to adhere glitter. Let the glue fully dry before gently tapping off excess glitter. You can coat the entire coaster in glitter or just add glitter accents.

Gems: Glue on flat-back gems, rhinestones, or crystal embellishments to add some shine to your coasters. Arrange them in patterns or designs. Glass beads or colored stones can also be affixed to the sealed clay.

Stencils: Use stencils and sponges to create patterns on your coasters with paint or glitter. Geometric shapes, animals, flowers, letters, and more can be stenciled on. Make sure the coasters are fully sealed first so the paint does not soak into the clay.

Get creative with additional decorations! Just be sure to only decorate coasters that have been fully sealed and cured first. This will protect the clay and keep your designs lasting longer.

Test for Waterproofing

Once your clay coasters have been thoroughly sealed and cured, it’s important to test how waterproof they are before using them. This helps ensure no moisture will penetrate through and damage your coasters or table.

The best way to test is to simply drip some water onto the surface of the coaster. Use an eye dropper or spoon to place several small drops of water in different areas. Allow the water to sit for at least a minute or two, so it has time to soak in if the sealer was ineffective.

Check if the water beads and sits on top of the coaster, or if it begins to soak in. Waterproof coasters will repel the moisture and it should bead up, without leaving any watermarks behind. If you notice the water absorbs or leaves behind wet spots, apply another layer of sealer and allow to fully cure before retesting.

Repeat the water drip test on both the top and bottom surfaces to ensure complete waterproofing protection. Your clay coasters are ready to use once the water rolls off the surface without any penetration or absorption into the clay material.

Care and Maintenance

Properly caring for your clay coasters will help protect the finish and extend their lifespan. Here are some tips:

Handwashing

It’s best to wash clay coasters by hand. Use a soft sponge or cloth with warm water and mild dish soap. Avoid abrasive scrubbers or cleaners that could scratch the sealer.

Avoid Abrasives

Don’t let clay coasters soak in water for long periods, as this can break down the sealer over time. Also avoid using harsh chemicals or cleaning products containing acids, ammonia, or bleach.

Reapplying Sealer

Expect to reapply a sealer coat every 1-2 years with regular use. Letting moisture penetrate the clay can cause staining or damage. When coasters start to lose their waterproofing, lightly sand them and add a fresh sealer for protection.

Troubleshooting

If your clay coasters become damaged or the sealer starts to peel or wear off, there are a few steps you can take to troubleshoot and fix them:

Blotching: This can occur if the sealer is applied too heavily or unevenly. Gently sand the coaster with fine grit sandpaper to remove any blotches or uneven sealer buildup. Wipe clean and reapply thinner, more even coats of sealer.

Peeling: If areas of sealer start peeling away from the clay, the coasters likely did not fully cure and dry before the sealer was applied. Gently peel away all of the sealer, then let the coasters dry for a few more days. Once fully cured, reapply the sealer.

Wear: Over time with repeated use, condensation, and washing, the sealer layer may start wearing away. This is normal, and the coasters will need to be resealed every so often. Lightly sand the coasters to rough up the surface, clean away any dust, then reapply 2-3 thin coats of sealer allowing drying time between coats.

With extra prep time and proper application of a quality sealer, your handmade clay coasters can be kept looking great while protecting your furniture from water damage and rings.