Some notes on using canvas

[shogun]

This one is going over in the Land of Sorcery so I can be a bit more specific. If you have not yet, take a look at the posts for “Samurai Sunrise” and “More Experiments With Canvas” to see what I am babbling about.

The basics are this: I start with a basic 8 by 10 canvas and go to town on it with some spray paint of various colors. If I want the finished image to have brighter colors, I throw two coats of clear over that when it’s dry, and let that sit overnight. If you want a more pastel color set, skip the clear coat.

Top this all off with a solid coat of paint (I used black for the most part) and let that dry completely.

Now comes the fun part (pew pew pew). The goal is engrave an image such that it removes the black in all the dark spots, but does not remove the colors underneath. What I have found so far seems to be go fast and use as much power as you can get away with before it starts removing the colors.

After some testing, I am using Speed 1400 / Power 40 and 225 LPI for most things (I am on a Basic). However there is some variation based on the paint type and the coat thickness (try to be as even as possible with your top coat).

I also discovered that Killz is pretty much laser proof. I can get through it at full power 1400, but just barely. Good to know this for when Alexa becomes sentient and takes control of the Glowforge… For the next canvas project I ordered some white acrylic spray paint to try instead.

You also want to invert any images you use otherwise you end up with a negative. This can also mess with your head a little since selecting an image in the glowforge UI inverts it to show it is selected.

More experiments to follow…

Update
After some additional experiments, I think upping the power is probably a good idea. I have moved to the 55-80 range in power. Light grey is still a bit problematic, but I have gotten around this in places by cutting the files up and isolating the dark blacks from the grays and giving the grays more power.

Recent prints:

A screenshot from No Man’s Sky

Some fractal clouds

A fractal mandala.

A combination image with a fractal and a concept image of a dyson sphere. This one is kind of cool because it’s the first one I have done with a white overlay instead of a black. I probably should have stepped the power up on this, but overall it’s still pretty cool.

[eflyguy]

It would be handy to know what specific paint you were using?

[markevans36301]

I really appreciate writeups like this. Even with all that I have done with it there are roads that I have never traveled but would like to.

[shogun]

Sorry. Forgot that. It was all basic Rustolium from Home Depot. The primer was Krylon , but seemed about the same if a little tougher. The Killz was not great.

[wesleyjames]

And that’s the first bookmark I’ve thrown in a while.

[jamesdhatch]

@shogun

The primer was Krylon

When do you use the primer? What color primer (gray)?

[shogun]

I used the grey primer as a top coat on one of my last designs here:

Further Experiments in Canvas

I spent most of Sunday and a few hours today playing around some more with canvas. Here are my results. The first canvas started out like this: [IMG_5479] And using an old B&W photo from my younger days, I got this: [IMG_5487] I played around with a few things and did the Orion Nebula from a nasa shot. The inverted photo looked like this: [Sound-Bath-Orion- 8 by 10 Inverted] The lasered canvas turned out like this: [IMG_5483] I went back and dotted in the stars with a silver sharpie. No…

I wanted to try something other than black as a top coat. I would have used silver if I had it or white. Grey primer was just handy.

[jamesdhatch]

Got it. Thanks. I thought the primer/paint brand comments were about the post up top, not the series you’ve been posting.

It’s a very cool technique though and like others first bookmark I’ve thrown in a long while

[bill.m.davis]

@shogun

I also discovered that Killz is pretty much laser proof. I can get through it at full power 1400, but just barely. Good to know this for when Alexa becomes sentient and takes control of the Glowforge…

Wow, I didn’t expect this comment, and it had me laughing pretty hard.

Thanks for the details! This is definitely something I will want to try out!

Edit: This is the first post I have ever bookmarked. I have never tried this feature before, this is definitely a post I want to come back and review! (Now I need to find a few other posts I remember seeing and bookmark them too!)

[evansd2]

How messy is this process? Long engraves tend to be messy in general but I wonder how much dust and gunk accumulates from blasting away all that paint?

[shogun]

Surprisingly little mess. There is a very light amount of dust in some areas, but no sticky residue at all. I wiped one down with alcohol and the cloth came away clean. An 8 by 10 canvas is about 50 minutes to an hour, but it really seems to just disintegrate the paint.

Which reminds me, I really need to do a dalek.

[evansd2]

I meant in the machine, optics, exhaust, gantry etc

[shogun]

Not that I have been able to see. I did a wipe down after the last canvas and it was no more dirty than my wood projects have been. Maybe a little less.

[lairdknox]

@shogun

Speed 1400

Off topic but speed 1400? What have I missed? I haven’t been online much for a while. I only see a speed of 1000.

[shogun]

So this is one of those weird vector vs bitmap things. Vector shapes, like the squares, lines and circles (or more complex shapes) can be engraved up to a speed of 1000. In this example, I have the square selected.

However, bit maps (images composed of dots or pixels) can go up to a speed of 1400. See the example below with the image file selected:

Not 100% sure why.

[eflyguy]

Depending on the settings, you can go up to 4000. It’s not much use at that speed, however.

Started last year:

Increasing the speed of light: four ways your Glowforge is getting faster (and...

[lairdknox]

Ah so only with bitmap images. Most of my engraves are vector so that’s why I missed it.

Thanks!

[rebecca]

Wow, these are amazing. Smart idea! You’re very cool to share and take the time to explain the process and share trials, errors, and settings.

On a side note, it reminds me of this thing I used to do as a kid with crayons. I’d make a layer of colors and cover them all with dark solid color. Then I’d take a fingernail and scratch an image through the top to reveal the colors underneath. (Did anyone else do this too?) Your projects are like the professional adult version.

The pictures a beautiful. Technique is one thing, but then there’s color, and then of course image selection. All are simply excellent choices.

[ekla]

Scratch Art! We did the same crayon thing in elementary school. But little sister went to a fancier school where they had the premade sheets you can buy at an art supply store. Even Daiso stocks it now in their art supply section.

[shogun]

Oh my god yes! I had forgotten about the crayon version from when I was a kid! Thank you for the reminder and the kind words.