Darker Burns

[Bert Kemp]

I know we've discussed this before but the problem I'm now having is the burn lightens up on the return pass.

I watch as the laser burns left to right its a nice dark burn but on the return ,right to left it then lightens up the engraving again. Is there a way in Lasercut 5.3 to only have it burn in one direction. or to keep the burn dark on return.?

I'm going to retract that was just watching again and maybe what I'm seeing is a shadow on the first pass and not a darker burn. I did take it out of focus about 1/8" and slow it down from 350 mmps to 200mmps and increased power from 15% to 30% but stll not were I want it.

[Matt McCoy]

What is the material?

[Bert Kemp]

Stained Baltic Birch 1/8 and 1 coat of sanding sealer on it.

[Rich Harman]

Is there a way in Lasercut 5.3 to only have it burn in one direction. or to keep the burn dark on return.?

Most likely. In LaserWorks you can choose "Unidirectional" or "Swing", surely there is the equivalent in LaserCut.

To get the best results using "Swing" (bidirectional), you need to tune the offset in the settings. I don't recall the terminology but it is something that should be done if you want the best results. It is for lining up the right-to-left pass with the left-to-right.

When I need the absolute best possible resolution I use unidirectional, but that is very rare.

[Scott Shepherd]

Air Brush it and be done.

[Samuel Espy]

These have all been discussed before as you note (which is where I got my ideas), but it does not hurt to discuss a topic again that can be so vexing. I recently went through a decent amount of testing to get dark burns on maple while trying to keep acceptable resolution in the final engraving. My recipe for results I deemed optimal for my machine and visual preferences are: 1) move table lower by 0.2" from focal plane for 2" lens (yes it is large, but my testing revealed I still had acceptable resolution); 2) max PPI (1000); 3) 333 DPI of image and 333 LPI on engraver (the overburn really darkens engraved areas; 4) use error diffusion for the dithering; and 5) 100P/60S on my 30W machine. Going a bit slower did darken it slightly more, but not sufficiently to warrant the longer engrave time for what I was doing.

[Bert Kemp]

OK will do ,please send me the air brush, compressor , hose's, the masking stuff I'll need and the paint or stain plus cleaning supplies so I can clean it before I send it back to you.:D:eek:


Air Brush it and be done.

[Bert Kemp]

Well I could be mistaken but I could be getting the darkest burn for the material I'm using. I get a rich tan burn but when I use a different wood like cherry or hard board my burn is a lot darker almost black, using the same settings. When I win that laser Dark I'll see what that can do :rolleyes: Maybe Scott has the right idea mask it and rattle can it. Its not that precise of an engraving that it will make a big difference anyway.




These have all been discussed before as you note (which is where I got my ideas), but it does not hurt to discuss a topic again that can be so vexing. I recently went through a decent amount of testing to get dark burns on maple while trying to keep acceptable resolution in the final engraving. My recipe for results I deemed optimal for my machine and visual preferences are: 1) move table lower by 0.2" from focal plane for 2" lens (yes it is large, but my testing revealed I still had acceptable resolution); 2) max PPI (1000); 3) 333 DPI of image and 333 LPI on engraver (the overburn really darkens engraved areas; 4) use error diffusion for the dithering; and 5) 100P/60S on my 30W machine. Going a bit slower did darken it slightly more, but not sufficiently to warrant the longer engrave time for what I was doing.

[Scott Shepherd]

Airbrush is $9 at harbor freight. I suspect the compressors there aren't much more. If you plan on doing much engraving in wood, it's worth the investment. You can engrave as fast as you want, about 60 seconds of actual paint time, let it dry for about 5 minutes, peel the paper off, and it's solid black engraving every time in any type of wood. It makes every wooden piece you do look the same, as far as engraving quality.

Or.....you can keep fighting it and find methods like Unidirectional that make your jobs run even slower ;)

[Samuel Espy]

Scott, I presume you are referring to using an airbrush in combination with masking for engravings that are not as complex as a photo. I don't engrave photos directly, but first transform them into something resembling a shaded pen and ink drawing. While these engrave much better than a photo on wood (to my tastes), these are still too complex to create a mask from transfer paper, etc. unless there is a low-cost trick I don't know about.

[Bert Kemp]

Time I have Money I Don't:D You make it sound so easy and cheap but I'm guessing its more expensive then 20 bucks to have everything you need , like all the stuff I mentioned , and then learn how to do it right. Not as cheap and simple as you think I'm sure. I don't do a lot of engraving some but I mostly cut and its just a hobby.


Airbrush is $9 at harbor freight. I suspect the compressors there aren't much more. If you plan on doing much engraving in wood, it's worth the investment. You can engrave as fast as you want, about 60 seconds of actual paint time, let it dry for about 5 minutes, peel the paper off, and it's solid black engraving every time in any type of wood. It makes every wooden piece you do look the same, as far as engraving quality.

Or.....you can keep fighting it and find methods like Unidirectional that make your jobs run even slower ;)

[Keith Winter]

Hi Burt,

I'm familiar with the Baltic Birch your burning. Dark tan is the darkest we have been able to get on that wood UNLESS you take it wildly out of focus. Then you can make it almost black but it will be shallow and crappy looking engraving.

Here are the settings we use, similar to Samuel, but the opposite on focus. I've experimented with both and I think the bringing it in looks better, but they are pretty similar methods, either will work. 1) Take it in (bring the table up) about 0.2" out of focus. 2) Max ppi on your laser settings (same as sam) 3) 333 dpi of image (same as sam) 4) We use black/white diffusion but I honestly haven't played with the others much. 5) Try a bigger lens, bigger lens equals bigger spot size and more overlap at higher resolution, meaning more burn.

All else fails Steve's airbrush method is sure-fire and guaranteed to work.





Well I could be mistaken but I could be getting the darkest burn for the material I'm using. I get a rich tan burn but when I use a different wood like cherry or hard board my burn is a lot darker almost black, using the same settings. When I win that laser Dark I'll see what that can do :rolleyes: Maybe Scott has the right idea mask it and rattle can it. Its not that precise of an engraving that it will make a big difference anyway.

Samuel Espy
These have all been discussed before as you note (which is where I got my ideas), but it does not hurt to discuss a topic again that can be so vexing. I recently went through a decent amount of testing to get dark burns on maple while trying to keep acceptable resolution in the final engraving. My recipe for results I deemed optimal for my machine and visual preferences are: 1) move table lower by 0.2" from focal plane for 2" lens (yes it is large, but my testing revealed I still had acceptable resolution); 2) max PPI (1000); 3) 333 DPI of image and 333 LPI on engraver (the overburn really darkens engraved areas; 4) use error diffusion for the dithering; and 5) 100P/60S on my 30W machine. Going a bit slower did darken it slightly more, but not sufficiently to warrant the longer engrave time for what I was doing.

[Keith Colson]

When I engrave wood I generally put the laser out of focus. This achieves a couple of good things. I can get an almost black engrave and it hides any raster lines when doing lower resolution engraves. If I got out of focus a lot I adjust the artwork to match the defocus.

Cheers
Keith

[Scott Shepherd]

Time I have Money I Don't:D You make it sound so easy and cheap but I'm guessing its more expensive then 20 bucks to have everything you need , like all the stuff I mentioned , and then learn how to do it right. Not as cheap and simple as you think I'm sure. I don't do a lot of engraving some but I mostly cut and its just a hobby.

Don't you have a compressor for your laser?

[Keith Colson]

Scott is so right, the stupidest thing I did this year was not buy an airbrush until last month. It is a must have in the engraving world. I can't think of doing cermark with out one. It can cost a little more as they may need fittings and a regulator but well worth it.

[Scott Shepherd]

Just a couple examples, nothing special or amazing, but it shows the type of results you get, one is in cherry, one is bamboo, and one is Spanish cedar.

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[Ross Moshinsky]

Are you sealing the wood first?

[Scott Shepherd]

Are you sealing the wood first?

Bert, or me? Me, no, unless it's already sealed. In my photos, the bamboo and the Spanish cedar are not sealed.

[Glen Monaghan]

I was engraving a bunch of rosewood and found that it tended to vaporize with little color change. I had to run slow and low power to "toast" the wood, but found a couple of pieces that still didn't have any contrast. I experimented with hand-darkening those with shoe polish, Rub-n-Buff, and a couple other options, but it's much quicker to spray-and-wipe (assuming you have a finish that doesn't react to your tint spray). I initially tried masking when a tint reacted with the finish, but the weeding was too onerous. Either apply a finish that doesn't react to the tint, or find a tint that your existing finish repels, and you can simply spray and wipe off the excess. Plus you can run the engraving much, much faster since you don't care what contrast it creates, only that you get the desired depth.

Instead of engraving for a piece for 90-100 seconds, slow and low power, and hoping for good contrast (but having to re-run, replace, or hand-tint the occasional piece when the rosewood simply wouldn't darken), I found that I could engrave in 20-30 seconds at high enough power for the depth I want and spend 10 seconds to spray and wipe for a consistent, dark, high contrast mark every time. Sure takes the fuss and bother out of the process...

That Laser Dark spray in the current give-away is supposed to be good for this sort of application. I think it has a clear over-spray that is supposed to go on afterwards, in case you need to seal the color in the engraving.

[Ross Moshinsky]

Bert, or me? Me, no, unless it's already sealed. In my photos, the bamboo and the Spanish cedar are not sealed.

Yes, the question was directed towards you. The only reason I ask is sometimes the paint will go into the grain and bleed and the results are less than desirable.

[Scott Shepherd]

Yes, the question was directed towards you. The only reason I ask is sometimes the paint will go into the grain and bleed and the results are less than desirable.


Gotcha, solved that problem ;) I can get that look on any finish.

[Ross Moshinsky]

Gotcha, solved that problem ;) I can get that look on any finish.

Trade secret or something you're willing to share?

[Bert Kemp]

Yes I do have a small air compressor for the laser guess that would work. These examples look awesome, now that I see what it looks like guess I might try it , can't cost that much and I add another tool to the basket. Thanks for these pictures Scott.



Just a couple examples, nothing special or amazing, but it shows the type of results you get, one is in cherry, one is bamboo, and one is Spanish cedar.

316318316320316319

[Bert Kemp]

Sometime yes sometimes no, I find that unfinished cuts easier, finer kerf, seem when I finish then cut I get a much wider kerf, might be just the finish melting that makes it look wider.



Are you sealing the wood first?

[Matt McCoy]

Hey Bert, this is what I usually aim for on BB (250dpi). The last pic shows the walnut material.

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316334

316335

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[Keith Winter]

These look fantastic Steve!

[Keith Winter]

Those are really cool and beautiful Matt! What type of laser and power are you running?

[Jay Selway]

When I engrave wood I generally put the laser out of focus. This achieves a couple of good things. I can get an almost black engrave and it hides any raster lines when doing lower resolution engraves. If I got out of focus a lot I adjust the artwork to match the defocus.

Cheers
Keith

I agree about taking it out of focus a bit. With my helix 24, I lower the table a bit (usually .2"). It burns much darker and also has the added benefit of less smoke residue on the wood (not sure why, but it happens). I would suspect that most of the residue is staying within the burn, which is why there is less smoke.

[Bert Kemp]

Yes thats what I get also but I would like a blacker color, guess the air brush is a must to get that.


Hey Bert, this is what I usually aim for on BB (250dpi). The last pic shows the walnut material.

316333

316334

316335

316336

316337

[Bert Kemp]

Your moving laser head away from your material and the smoke residue is less and drawn out quicker, there for less residue. The reason I option to go down rather then up out of focus.


I agree about taking it out of focus a bit. With my helix 24, I lower the table a bit (usually .2"). It burns much darker and also has the added benefit of less smoke residue on the wood (not sure why, but it happens). I would suspect that most of the residue is staying within the burn, which is why there is less smoke.

[Matt McCoy]

Those are really cool and beautiful Matt! What type of laser and power are you running?

I appreciate the kind words.

It's a Full Spectrum 24x18 90W (G.Weike LG 6040N)

[Glen Monaghan]

spray a clear coat first to seal the grain/pores, let dry, then tint. Just about mandatory for stuff like oak with big pores, not so much for others.

[Bill Reibelt]

Nice try Bert
Bill

[Scott Shepherd]

spray a clear coat first to seal the grain/pores, let dry, then tint. Just about mandatory for stuff like oak with big pores, not so much for others.

Oh, I don't know Glen, I think Bamboo trumps Oak by a mile for wicking paint, but as you can see in the photo I posted, that's unsealed bamboo, painted black, no wicking.

[Kev Williams]

So, what do you use for paint? Water based, enamel, screen print ink, wood stain, gloss, semi-gloss, flat, broke-open sharpie...?

[Glen Monaghan]

Scott hasn't answered/isn't answering and, given his responses so far, it seems likely that he doesn't intend to divulge his process further. I'm guessing it probably has to do with misting a light, fine spray that essentially dries on contact, something most people don't do with rattle cans. It may also help to use a heavily pigmented paint rather than a dye- or stain-based formula, again sprayed almost dry because, if it goes on heavy enough to stay wet, whatever you use is likely to wick into open pores and grain.

[Bert Kemp]

Everyone talks about wicking into the open pours. what if you seal the open engraving with a clear coat then spray your color would that eliminate the wickings into the open pours?



Scott hasn't answered/isn't answering and, given his responses so far, it seems likely that he doesn't intend to divulge his process further. I'm guessing it probably has to do with misting a light, fine spray that essentially dries on contact, something most people don't do with rattle cans. It may also help to use a heavily pigmented paint rather than a dye- or stain-based formula, again sprayed almost dry because, if it goes on heavy enough to stay wet, whatever you use is likely to wick into open pores and grain.

[Ross Moshinsky]

Everyone talks about wicking into the open pours. what if you seal the open engraving with a clear coat then spray your color would that eliminate the wickings into the open pours?

That's a common way of doing things. It works fine. It's less common to spray black into maple/alder/bamboo and not see any wicking.

[Mike Null]

I've had some luck using liquid floor polish as a sealer on the open grain. Red oak and ash are the worst woods I've encountered. I don't like bamboo so don't engrave it.

[Glen Monaghan]

Spraying a clear coat before the tint coat is what I had originally suggested, because that is what I did when I first encountered the wicking problem. Scott countered that he didn't need to resort to such "sealing" coats before tinting, and avoiding the sealing step offers the potential of reducing total time required for the finish process because you don't have to wait for the clear to dry.

[Bert Kemp]

I've used mop and glow as a sealer on cheap luan from HD and it works pretty good, but my concern with that is will paint adhere to it with out flaking off after a while. If I use a water base clear coat to seal the open engraving then a water base paint over that It should be ok but floor polish I'm not sure would hold the paint.


I've had some luck using liquid floor polish as a sealer on the open grain. Red oak and ash are the worst woods I've encountered. I don't like bamboo so don't engrave it.

[Martin Boekers]

Always been curious...anyone ever try Rain X?

[Bert Kemp]

But how does he avoid the wicking problem:confused: Scott care to elaborate



Spraying a clear coat before the tint coat is what I had originally suggested, because that is what I did when I first encountered the wicking problem. Scott countered that he didn't need to resort to such "sealing" coats before tinting, and avoiding the sealing step offers the potential of reducing total time required for the finish process because you don't have to wait for the clear to dry.

[Mike Null]

Bert

I'm using mop n glo. I'm applying it only to the engraved surface. Then I paint it with acrylic using a brush. It doesn't come out.

[Bert Kemp]

I'll give it a try Mike Thanks


Bert

I'm using mop n glo. I'm applying it only to the engraved surface. Then I paint it with acrylic using a brush. It doesn't come out.