You can alter the color of Titanium. The laser is just a precise application of heat. Heat changes the layer of oxidation on titanium. Certain temperatures can cause different colors.
I made this in Techshop.
Step 1: Create Image
I created the image I wanted to engrave in Adobe Photoshop. You can use whatever image editing software you want. I saved it as a Jpeg and imported it into Corel Draw. Make sure the colors are RGB values so they can be translated by Corel and Job Control. As you can see, I have three distinct colors.
Once you have imported the image and confirmed the colors are RGB, go to FILE > PRINT and choose Trotec Speedy 300 as the printer.
Step 2: Job Control Settings
Once in Job Control, choose the metal: Aluminum Anodized settings. We are going to tweak these settings.
As you can see in my screen cap, the colors were somewhat altered by Job Control. So I chose the corresponding colors. Now I was testing out settings so you may want to tweak these settings to get the desired results.
From personal experience, Titanium changes colors under certain temperatures. I would use a propane torch and heat titanium to give it a rainbow coloring. This can be done with the laser and direct onto the bare titanium.
The settings I used are:
Yellow: Power 100 Speed 20 PPI 500
Red: Power 100 Speed 15 PPI 500
Black: Power 100 Speed 8 PPI 500
Step 3: Place Your Object in the Laser
Put your piece of Titanium in the Laser Bed. Align the laser and check the focal height.
I prefer to position the visible laser at the top center of my object and drag my image, in Job Control, to the laser position.
I recommend taping the object down as the motion of the laser can cause vibration and make the object move. In my case, my titanium spork shifted position as the laser moved.
Step 4: Laser Away!!
Here is a video of the laser engraving into my titanium spork.
There is a spray called CerMark that some people use. However CerMark has a different result on metal. You spray it on the metal and the laser heats up the chemical and creates a black image. I wanted the coloring effect which you can see in the image above. That is what I was trying to replicate.
For more information about the laser and to find a Techshop near you, go to http://www.techshop.ws/