Tag Archives: shade engraving

105: Tint and Shade Engraving

A close-up showing off the depth of the shade engraving.
Tint engraving is light, frosting the finish, while shade engraving is deep, darkening the surface.

Over the past few weeks, I’ve spent half a day here, half an hour there, slowly going through all of the inventory I’ve accumulated since starting my collection of laserable bits back in 2011. One of the gems I pulled out of the rough was a set of about a dozen small pieces of finished wood I scavenged from Eagle Engraving’s scrap material a year or so ago. I picked it up because I noticed that the finish reacted to light engraving in a unique way, but it got lost in the stack and forgotten.

I wrote about using halftones to get more than one shade when engraving wood recently, but approximating a handful of darker shades of the wood’s surface color can only have a certain pretty small range of values. It’s better than the usual duo of the untouched wood color and a single full-engraving shade, but what about lightening the wood color? It’s not really something that can happen on untreated wood—even the darkest wood just gets darker when burnt—but wood with a clear coat of certain chemicals can sometimes frost like cell-cast acrylic does. That’s exactly what Eagle’s scrap wood was doing, so I nabbed some to experiment with both shading and tinting on a single piece.

The first batch of prototypes showed that halftones couldn't be used.
The first batch of prototypes showed that halftones couldn’t be used.

I call this “tint and shade engraving” because of its parallel to a concept in color theory, though I am sure there is already a sufficient technical term for this type of double engraving out there; let me know if you know the answer!

I started out trying to recreate a section of the castle map from an old PlayStation game I was fond of, Castlevania: Symphony of the Night. I was hoping to create a physical map of the castle, starting with just the Entrance for now, and the added value range afforded by the tint engraving would really help the room graphics stand out over the wood grain.

Finding the right threshold for the tint and shade graphic layers was difficult.
Finding the right threshold for the tint and shade graphic layers was difficult.

Figuring out the shade engraving settings was easy enough, but I made a quick test cut to determine the best laser power settings for tint engraving for this material. The result looked like 15% (on a 40w laser, at 100% speed, on this specific material; YMMV!), so I started a series of test engravings on the many small pieces of wood I had available.

Coincidental background shading and foreground tinting created great contrast.
Coincidental background shading and foreground tinting created great contrast.

I quickly learned that I wouldn’t be able to use halftone patterns when shade engraving on this material. Because of the same clear coat that allows us to tint engrave, a tiny white outline appears around every shade engraved section. It’s tolerable in the final pieces (take a good look at the close-up shots to see what I mean) but with halftone pattern it got really visible and completely ruined any properly shaded effect.

Using halftone patterns on the tint engraving had better success, but was far less effective than halftone on a more traditional engrave, so I opted to use just one tint and just one shade. While it meant that we technically have less values than were used in the halftoning wood examples, the contrast is way higher and the result is much more striking.

A small section of Castlevania's Entrance. Do you recognize it?
A small section of Castlevania’s Entrance. Do you recognize it?

Once I had the prototypes engraved, I engraved and cut out a small subsection of the Entrance area of the game. It turned out pretty awesome, but because I only have smaller pieces of this particular wood at the moment I wasn’t able to complete the entire Entrance area as originally planned. I’ll just have to revisit that project another time. For now, another tint & shade engraving would suffice: the beautiful Ayami Kojima promotional painting that I still have an old wall scroll of somewhere in this office.

The processed art used for the shade engraving.
The processed art used for the shade engraving.
The shade engraving is complete, and tint engraving is up next.
The shade engraving is complete, and tint engraving is up next.
The processed art used for the tint engraving.
The processed art used for the tint engraving.
A close-up showing off the depth of the shade engraving.
A close-up showing off the depth of the shade engraving.

Like with the castle maps, I fired up Photoshop and went about adjusting levels and all that to build two engraving rasters, one for the shade engraving and one for the tint engraving. I engraved the shade first, snapped a quick picture in the laser to show off the piece mid-process, and then engraved the tint layer. The shading turned out way better than I expected even after the positive results with the in-game map, and I suspect that all sorts of well-shaded facial photography and artwork would engrave really well with this procedure.

The only trouble is finding exactly the right kind of finished wood! I have several coated woods and only some of them have the same frosting effect when lightly engraving. Maybe some of you out there know of good sources of wood specifically coated to provide this effect. Let me know if you do!