You'd normally expect to need an xTool F2 Ultra UV for photos on K9 crystal. The regular xTool F2 can do a really good job too. It isn't inner engraving, the photo sits on the surface, but with a coat of paint and the right settings it looks great, and it adds another string to your F2's bow. If you have an F2 Ultra UV and want the photo inside the crystal instead, my crystal inner engraving guide covers that.
Here's my full process on light-up crystal keyrings, step by step, with the settings I worked hard to get. The same technique works on K9 crystal blocks as well.
Jump to: What you need · Paint the crystal · Raise it and focus · Prepare the photo · Frame it · Settings · Wash it off
What you need
- Black tempera paint. Any black tempera should work.
- A paintbrush (a smaller one than mine is better) and a little pot for the paint.
- K9 crystal blanks. I used keyrings from AliExpress. You can also find them on Amazon, and xTool sells similar ones. Mine have a light inside, which really shows off the photo.
- Something to lift the crystal off the bed. I use my Self-Centering Jig.
- Extraction, because you're burning paint off.
Paint the crystal
The paint is what makes this work. Crystal is clear, so the blue laser would go straight through it. The paint gives the beam something to react with, and that's what leaves the white image behind.
- Make sure the surface you're painting is clean.
- Pour a little paint into your pot. You don't need much.
- Brush on an even coat, painting lightly over the top so there are no ripples.
- Let it dry.
Get the thickness right. A thicker coat is harder to engrave through, but you don't want it so thin you can see the crystal through it. Mine had a few thin patches. If you find a better way of getting an even cover, use it.
Raise it off the bed and focus
Don't engrave a crystal sitting flat on the base plate. Once the laser gets through the paint, the crystal is see-through, so the beam carries on to whatever is underneath.
I close the self-centering jig's standoffs down, rotate it, and sit the keyring on top so it's lifted off the bed. The jig also lets me make small adjustments to the position later.
To focus, turn the knob on the side of the F2 until the two dots join together. Then you're at the right height.
Prepare the photo in xTool Studio
- Click New project in the top right. Studio connects to the F2, beeps, and takes a snapshot of the bed.
- Set the material first. Click the material in the top right and pick Clear Soda-Lime Glass, then Apply. This matters, because Studio uses the material when it adjusts your photo later.
- Remove the background. If you leave it in, Studio engraves the background and the person together, and it washes the person out. I use Canva (Photo editor, then BG remover), which I pay for, but search for a free background remover and there are plenty of others. Download the result.
- Back in Studio, click Import and bring in the cut-out photo. Resize it with the corner handles and roughly position it on the crystal.
- Add a mask so it fits the shape. Right-click the photo, choose Create mask, pick the circle from the shapes on the left, and drag it where you want it. I made mine a bit bigger to get his shirt collar in. Click Done.
- Hold Ctrl and scroll to zoom in, then size the photo so it fills most of the crystal.
- Select the photo, click Adjust in the top toolbar, then Auto adjust.
On crystal the photo has to be inverted, or it engraves like a negative, with the light and dark areas swapped. Because you set the material first, Auto adjust inverts it, makes it black and white, and sets the contrast, brightness and sharpness for glass. You can do all of this by hand in the same panel if you'd rather.
Frame it
- Click the three dots next to Framing in the bottom right. You'll see Rect, Outline and Polygon. Hover over them to see what each does.
- Pick Outline, so you see the actual shape of your design. My light power was on 10.
- Click Framing and check the crystal. With the jig, you can rotate it to get it straight.
- For small tweaks, use the arrow keys on your keyboard to nudge the design. The framing box updates as you go.
My K9 crystal settings for the xTool F2
I tested a lot of crystals to get to these. Select the photo and set:
| Setting | Value |
|---|---|
| Laser type | Blue light |
| Dot duration | 375 µs |
| Power | 80% |
| DPI | 325 |
| Bitmap mode | Jarvis |
| Passes | 1 |
Click Process. These are quick. My keyring was estimated at 23 seconds, so if you're making them to sell or as gifts, you can do a lot of them. Click Start.
Paint thickness can change the result. Before you take the crystal out, have a look. If there's a lot of paint left, run a second pass.
Wash it off
Put the keyring in a bowl of warm water and rub the paint off with your fingers. Screw the top on tightly first, because there's a battery inside. It gets a bit messy, but the warm water helps. Give it a good wipe and you're done.
Turn the light on and it adds a bit more to it. The same technique and the same settings work on K9 crystal blocks too. Put one on a light base that shines up through it and you've got a lovely gift or something to sell. It's on the surface rather than inside the crystal, but if you've only got the F2, it's a great option.
If you have an F2 Ultra UV, that machine can engrave inside the crystal instead, which needs a completely different setup.
All my tested F2 settings are on the xTool F2 settings page, including the glass settings, in my free Laser Settings Library.
Who are you making one for?
Let me know in the comments on the video how yours turns out. If you find a better way of getting an even coat of paint on, I'd love to hear it.
