A frequently asked question from customers regarding laser engravers is how to laser cut plywood or MDF without scorching the substrate. Laser engravers can be used to engrave or cut. Engraving is not a problem because the power level on the beam isn’t high enough to scorch the wood beyond what’s expected. But cutting something thin like plywood requires more power and generates more heat. So much so that the act of cutting the wood can scorch it and mar the finished product. It won’t bother everyone. But your more picky customers may balk at accepting an intricately laser cut wood item with burn marks all over the surface. Fortunately, there’s a simple, low tech solution for this problem.
Low Tech Tape
One might think the solution to a problem with a high-tech device like a laser engraver would be a specially designed widget or gadget. Not so. The scorching of laser-cut plywood is prevented by a simple layer of masking or transfer tape. Just apply a layer of transfer tape to the plywood or MDF before cutting (See Fig 1). A medium tack paper tape like MAIN PerfecTear Plus would be a good choice. If you’re using a 30 watt laser like the Pinnacle MIII, start with settings of 2% speed and 100% power at 500 DPI and 400PPI. Adjust as necessary. And of course, remove the tape afterwards.
Sealing the surface
Why does applying a simple layer of tape to the wood prevent burn marks? Does it reduce the temperature of the laser beam on the wood? No. The burn marks on the wood aren’t really caused by the heat of the laser on the wood or MDF. The singeing is caused by the interaction of the air next to the wood in the beam of the laser. That air gets combusted right next to the surface of the plywood and causes the scorched effect. The application tape prevents this by sealing the surface of the wood and keeping the burning oxygen away. There will still be a darkening of the edge of the wood where it’s been cut, but the surface will be unmarred and ready for your most discerning customers.