The perfect wood for laser photo engraving
Wood can be one of the most challenging materials to laser engrave. This is mainly due to the inconsistencies in wood. As you can see in the above video and images the engraving results can vary even with similar color wood types. Here are a list of qualities to look for in selecting wood for laser photo engraving. Ideally the wood will have a high resin content, be light in color, and will not have a coarse or heavy grain. As mentioned this is ideal however, due to wood being a natural product it's not always achievable. We'll go over the above mentioned qualities in more detail below.
Sometimes being "Sappy" is good
Wood generally burns darker or lighter depending on the resin or sap content. If the resin content is high then the laser beam will burn the resin and drive it into the wood resulting in a dark burn. If the resin content is low the laser beam will vaporize the wood leaving only a minimal burn. Alder and Cherry wood usually have a high resin/sap content.
Very Important note regarding resin/sap content. Let's say you find a good quality wood that laser engraves with a nice dark burn. One day out of the blue the same wood is not engraving as dark as it use to, instead it seems lighter. Nothing has changed, your using the same settings, same wood vendor, same everything. One possibility of the sudden change in burn color is that the tree was cut down in the fall or winter month's. Huh? If you do a study on trees you will find that most tree's drop their sap down to the bottom of the trunk in the fall to prepare for the winter month's ahead. In the spring the sap redistributes in the upper portion of the tree. So what all this mean's for the laser engraver is that if the tree is cut down in the fall or winter and the upper portion of the tree was used for the plaque, the resin content will most likely be lower.
So how can you know if the plaque has a low resin content?
The best way to determine the resin content is to run a test on the back side of the plaque to be engraved. A great way to run a test without ruining the piece is by laser engraving your company logo on the back. By doing this you can accomplish two task, first your determining the darkness of the burn and second your branding your product. An alternate method to determine if the plaque has a low resin content, is if the plaque is lighter in color than that wood species normally shows, it may be lower in resin. Although this method of checking the resin content is usually accurate I highly recommend doing the burn test on the back.
It's all about the contrast
Engraving a photo onto a beautiful piece of dark hardwood like walnut will quickly turn it into a "What is that?" plaque. Some may not mind a dark photo on a dark piece of wood but for the rest of us we want to see the detail of that special photo we've carefully selected.
In order to get the best possible contrast you will need to find a wood that is light in color. White eyes can only be as white as the natural wood color. So if the wood is dark, the eyes will be dark and if the wood is a light red, you guessed it they will be light red.
Stripes, great on Zebra's not on photographs
What's the first thing that catches your eye when looking at a Zebra? The stripes! Wood has a very similar effect on the eyes. This is because our eyes are naturally drawn to to character/grain of the wood. For furniture a heavy grain/streaking is usually desired but for photo engraving it's a distraction and will quickly rob the photograph of detail. When laser photo engraving you want to choose a wood that has a smooth consist grain with minimal streaking. So what is a smooth consistent grain? A wood with nominal alternating light and dark streaks. Notice that both pieces have streaking however the cherry wood has roughly three times more compared to the alder and are much closer together. In our comparison above, the detail is the same on both pieces from a engraving standpoint but one looks clearer and more detailed than the other, the alder wood. Both pieces produced a dark burn and are light in color however, since the cherry has such heavy streaking the photograph is disrupted, appearing less detailed.
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Our top three choices for laser photo engraving on wood