What's the difference between Proofgrade Hardwood & Plywood?

Indeed - it’s specifically that the grain is rotated 90 degrees from layer to layer that gives plywood it’s strength. It has stability and strength in both the X and Y. MDF is baked goo.

“Proofgrade™”, often denoted on the forum by the :proofgrade: symbol (emojis can be entered via the smiley in the toolbar or by a keyword surrounded by colons—“: proofgrade:” without the space after the colon in this case) is a Glowforge trademark for the materials they sell that have been made to their specifications and which they warrantee will work properly with the Proofgrade™ settings in a Glowforge.

As others have mentioned, other sources of plywood or MDF board may work just fine—many here like using Baltic Birch, for example—but it is up to you to figure out what settings to use (#beyond-the-manual is where people discuss settings). Others may contain materials that give off toxic fumes, or gasses that can damage your laser. For example, never laser PVC (polyvinyl chloride) as it releases hydrochloric acid that will eat your Glowforge.

Other materials may look the same, but have very different cutting properties—even when bought from the same store a week apart—because they don’t always get them from the same source, or they vary by lot even with the same source.

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Thanks everyone for the helpful information. @ntl, did you have any additional questions?

I’m good. This was helpful - Thanks!

Glad to hear it! I’m going to close this thread. If you have any more questions, please start a new thread or reach out to us at support@glowforge.com