Article · Wikipedia archive · Last revised Jul 28, 2026

Medium density overlay panel

Medium density overlay panel, or MDO panel, is a paintable surface made of plywood with a weather-resistant resin overlay bonded to the wood by heat and pressure. The overlay, which has at least 27% resin content, resists water, weather, wear and degradation. A similar product with a more rugged, smoother surface is called high density overlay (HDO) plywood.

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Jul 28, 2026
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Medium density overlay panel, or MDO panel, is a paintable surface made of plywood with a weather-resistant resin overlay bonded to the wood by heat and pressure. The overlay, which has at least 27% resin content,1 resists water, weather, wear and degradation. A similar product with a more rugged, smoother surface is called high density overlay (HDO) plywood.2: 4 

Development

Originally developed for sign painting and concrete formwork industries, MDO is also used for other applications2: 5  as a paintable surface. Paint finishes on MDO are up to three times more durable than the same finish applied to ordinary plywood

It is a plywood product, with a paper face overlaid on the plywood substrate with an exterior grade (usually) phenolic adhesive. MDO is designed to have a smooth, paint-receptive surface. One or both faces can be surfaced with paper, and is produced in 4-foot-by-8-foot sheets from 3⁄8 inches to over 3 inches in thickness.

References

References

  1. Voluntary Product Standard PS 1. APA - The Engineered Wood Association. 2009. p. 20.
  2. HDO/MDO Plywood Product Guide. APA - The Engineered Wood Association. 2011.
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