Our Mosaic Backer Boards are cut from 1/2-inch cabinet-grade sanded plywood (either maple or birch based on availability) and are suitable for indoor mosaic projects such as plaques and trivets. The bottoms of the plywood boards are gloss finished to prevent staining, but the edges are infinished cuts, which can be left as is or painted with a neutral color of acrylic paint, stained with wood stain, etc. We have more information about backers for mosaic projects at the bottom of this page.
Backers for Mosaic Projects
- Material: cabinet-grade sanded plywood (either maple or birch based on availability).
- Dimensions: within 1/32 inch of nominal dimensions.
- Thickness: 1/2 inch.
- Suitable for dry indoor use only.
The face of the board may have small splinters missing from the sawing process, but these will be covered by the mosaic.
Using the Mosaic Backer Boards
The Mosaic Backer Boards are plywood and are meant for indoor use only.
The gloss side of the plywood is the bottom. You should attach your tiles to the bare side of the wood.
The bare side of the wood should be painted with dilute Weldbond or another PVA adhesive to make sure that the wood doesn't suck water out of the grout while it is curing. You can dilute the Weldbond 1:1 with water to help it spread more easily on the wood.
The pattern for your mosaic can be drawn directly on the wood with an ordinary pencil. You should do this before coating the wood with Weldbond. If you forget, you can draw the pattern on the wood with a Sharpie marker.
Make sure that your tile doesn't stick out beyond the edge of the wood, which would make it particularly vulnerable to being knocked loose or chipped by random blows over time.
Indoor Vs Outdoor Mosaics
Wood of any type including plywood should NEVER be used for outdoor and wet mosaics because wood swells and contracts with changes in humidity, which will cause tile to pop off long before the plywood begins to show signs of warping. For outdoor mosaic projects, you must use stone or concrete if you want the mosaic to last for more than a year or two. For wall murals, mount the mosaic directly on a stone or masonry wall or use concrete backer board such as sold for underlaying bathroom tiling. For garden mosaics, use slabs of field stone or concrete stepping stones. Remember to scuff these with a wire brush to remove contaminants, sealers and loose material before mounting the mosaic with thinset mortar.
Indoor mosaics not subject to water can be made on plywood to save weight. There is no need to use stone or concrete backer board as the backer or thinset mortar to attach the tiles. Instead, the tiles can be mounted using a white PVA adhesive such as Weldbondand then grouted.
More How-To-Mosaic Information
For more advice on designing your mosaic project or cutting and grouting tile, please see our Mosaic Frequently Asked Questions or our List of How-to-Mosaic Pages, which are described by topic.
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