Laser engraving darkening

[Nigel Morgan]

Hi All,

Any tips to do this other than "Laserdark", shoe polish or something.

Cheers

Nigel

[Dave Fifield]

Hi Nigel,

I've not tried to darken a lasered piece after I have engraved it, but here are some ideas. The best wood for a good dark engraving is alder. Nice contrast ratio. When I need the engraving to stand out, I use laser masking tape (from Laserbits) to cover the whole piece, then engrave it, then fill it with gold or silver paint and remove the un-engraved laser masking tape when the paint is about half dry. You could try black paint or boot polish using this method.

If you don't want to do any filling after engraving, you could try decreasing the power a bit at the same time as decreasing the speed - you might get a longer "burn" on the work. You could also try running it without air assist on (but make sure you don't leave it alone - it could catch fire!).

Dave F.

[Bruce Volden]

Nigel,


I like the colored car waxes, tho some (white) doesn't always work out:(


Bruce

[Joe Pelonio]

Hi Nigel,

I use laser masking tape (from Laserbits) to cover the whole piece
Dave,

Transfer tape from a wholesale sign supply is about 1/2 the price of the laserbits mask for the same thing. In fact I buy it in 48" logs cut to useful lengths and end up with extra 2-4" rolls that I'd give away if someone in
Seattle area wants to stop by the shop.

Nigel,

I'll mostly use paint, and find that One-shot is best but latex is better than spray cans which are thinner and can bleed into the wood. One shot is oil based and nasty fumes but amazingly good stuff. For denser materials spray paint like Krylon works.

[Doug McIntyre]

If you simply want to increase the darkening a little more than normal - run the engraving out of focus by up to 1/4" either way.

A little experimenting at different focal lengths sometimes improves the job considerably.

[Lee DeRaud]

You didn't mention what material you're working with...makes a bit of a difference.:p

But for wood, the best contrast I've seen is with the thin baltic birch plywood they sell for model airplanes. This is straight out of the laser (25W ULS, 100% power, 50% speed):
33882
Trick is to just burn off the top layer: next layer down is darker, plus the burnt wood (and maybe the glue) turns it jet black. Shoot it with some spray shellac or lacquer to keep the 'soot' from coming off.

[Joe Pelonio]

Trick is to just burn off the top layer: next layer down is darker, plus the burnt wood (and maybe the glue) turns it jet black. Shoot it with some spray shellac or lacquer to keep the 'soot' from coming off.

Lee's right, I also ran into this on a book (Journal) cover that was very light tan thin leather. I burned the lettering into it and the lady wanted it deeper. The next pass was into the hardboard underneath that happened to be black so it worked out nicely.

[Dave Fifield]

Thanks for the tip Joe. Next time I need a roll, I'll go to a sign supplies dealer. :)

[Nigel Morgan]

Hi All,

Thanks for all the tips, I am working with solid 6mm Beech, every piece burns different, I colour the raster area red to get the best dither effect, some times it burns not black enough so I have to darken that item myself, hence the question. I thought last night of using a wood dye on the area or ink, I need to get hold of a syringe with a fine point, then I can save the rejected items.

Cheers

Nigel

[Roy Barrow]

I do a lot of red alder plaques and the process I use is similar to several mentioned here however....

1> mask the plaque with transfer tape (vinyl sign transfer tape is great and low tack).

2> engrave the plaque.

3> spray the engraved area with a Krylon Clear acrylic to seal the wood grain and prevent bleed...let it dry.

4> then paint with whatever color you wish...I use a brown satin (Krylon is fine) for best contrast.

5> scrape/peel the transfer tape from the plaque using a plastic squeegee (get from a sign vinyl supplier).

6> I use a microfiber cloth and a squirt of GooGone to polish the plaque.

The result is great very high contrast brown that you cannot achieve with laser alone...customers are VERY happy!

[Dennis Perry]

Nigel,

I don't do much engraving but this seems to work ok for me.
I use .25" pre-finished oak over mdf both sides. Not sure of the finish possible a heat activated poly, the finish is very nice on both sides. Cost about $40 4' X 8'.
On a 100 watt machine at 100% speed 20% power dpi 250 same as drawing. After engraving I apply a dark oil based stain and wipe clean. No masking required because the wood is pre-finished.
Piece is 8" X 8", it's the war departments crew.:D :cool:

Dennis

37064

[Raphael Weil]

You guys think this is just two passes on birch? I know the wood is birch and clearly it's mid-second pass. I was just surprised to hear that there was no need to add any sort of external chemical to this process. That's just how birch and alder burn? I can't wait to try this....

335635

[Rich Harman]

You guys think this is just two passes on birch? I know the wood is birch and clearly it's mid-second pass.

It looks to me like it is four separate items placed close together.

[Matt McCoy]

It looks to me like it is four separate items placed close together.

Me too. I don't think it would be possible to obtain that contrast by engraving alone.

[Rich Harman]

Me too. I don't think it would be possible to obtain that contrast by engraving alone.

Oh, I think so. That's because the part that has been engraved is the same color in all four, it's just that three were painted black before engraving. That's assuming those were actually laser engraved, do we know for sure that's what was done?

[Raphael Weil]

Oh, I think so. That's because the part that has been engraved is the same color in all four, it's just that three were painted black before engraving. That's assuming those were actually laser engraved, do we know for sure that's what was done?

That's a picture taken inside the laser bed mid-engrave. The machine broke down at that step. He has several panels side by side by side. Nothing was painted. You can see where the laser head stopped.

[Matt McCoy]

Oh, I think so. That's because the part that has been engraved is the same color in all four, it's just that three were painted black before engraving. That's assuming those were actually laser engraved, do we know for sure that's what was done?
Hard to tell on a tablet. The piece in the foreground looked like BB that is laser engraved since the darker positive space looks pretty typical of the end result. Although when I zoom the pic, i guess it could be stained. ???

[Bill Munroe]

For wood, I have found that finishing the piece before lasering (I usually sand, use danish oil with a top coat of shellac, then wax) then engraving, then going over with gel stain gives very good results. The dark gel stain wipes off of the shellacked surace without staining darker. The gel settles into the engraving and gives excellent contrast. If using mask and paint, I would strongly suggest you use shellac prior to applying the paint, as it will help prevent bleed. Again, this is for wood. Never tried it with any other material.

[Raphael Weil]

For wood, I have found that finishing the piece before lasering (I usually sand, use danish oil with a top coat of shellac, then wax) then engraving, then going over with gel stain gives very good results. The dark gel stain wipes off of the shellacked surace without staining darker. The gel settles into the engraving and gives excellent contrast. If using mask and paint, I would strongly suggest you use shellac prior to applying the paint, as it will help prevent bleed. Again, this is for wood. Never tried it with any other material.

What sort of wood are you using that with? If I understand correctly you're getting the gel stain into the fresh grooves you've engraved to create more contrast?

[Dan Hintz]

That's a picture taken inside the laser bed mid-engrave. The machine broke down at that step. He has several panels side by side by side. Nothing was painted. You can see where the laser head stopped.

Then why is the pattern right at that line different on either side? It's close, but different. Those are two (or more) pieces...

[Bill Munroe]

I've used on any wood that I felt like I didn't get a good enough contrast, although I have never tried it on plywood. You understand correctly in that the gel stain settles into the fresh "grooves" made by the laser. Again, I always finish/shellac my wood prior to engraving. That way, if I apply the gel stain, it wipes off the surface easy without changing the surface color. leaving the darker stain in the engraving.

[Raphael Weil]

Then why is the pattern right at that line different on either side? It's close, but different. Those are two (or more) pieces...

It's 4 skateboards side by side by side. The laser stopped right after the point you see there.


I've used on any wood that I felt like I didn't get a good enough contrast, although I have never tried it on plywood. You understand correctly in that the gel stain settles into the fresh "grooves" made by the laser. Again, I always finish/shellac my wood prior to engraving. That way, if I apply the gel stain, it wipes off the surface easy without changing the surface color. leaving the darker stain in the engraving.

Very cool. I'll try and figure this out without gel, but if that's what it takes I'll try. Just got really nice contrast on ply just by doing a 2nd pass, curious how much darker the gel would take it.

[Raphael Weil]

Here's another from the same artist, can clearly see it's some sort of effect happening in the plywood. Either naturally or with a gel. There's no painting going on here that I can tell. This is maple ply

335685

[Lee DeRaud]

Here's another from the same artist, can clearly see it's some sort of effect happening in the plywood.Can't tell how deep the engraving is there, but it's certainly possible that it's getting all the way through the top layer into the glue and burning it black. (see post #6 above)

[Brian Lamb]

Judging by the darkening on the non-ingraved ares of those two cards, I would guess that is some sort of applied stain.

[Raphael Weil]

Judging by the darkening on the non-ingraved ares of those two cards, I would guess that is some sort of applied stain.

Ya I see that now. So mask it, engrave it, spray it. I'll have to try and see what it yields.

[Brian Lamb]

Not really masked, like what Bill Munroe said, have a finish on the wood, laser it and then wipe stain on the engraving and it will wipe off the top, except where there might be enough surface imperfection to hold any stain. That's what I see in the cards below, like they have linear scratches from sanding in the top surface... you can see a bit of the stain hanging in there and muddying up the top surface. At least that's my guess from the pictures....

[Don Corbeil]

Yes, this looks like it was stained after engraving to darken, as you can see the bleeding into the grain. I get that result when I engrave and stain the lasered area. That's a method I use often, but the sanding doesn't always get all of the bleeding out. What I'll often do to minimize the bleed is to engrave, sand, sealcoat, then stain the engraved area. I'll use Restor a finish (dark oak) for the stain. It looks natural, and works pretty well.


Here's another from the same artist, can clearly see it's some sort of effect happening in the plywood. Either naturally or with a gel. There's no painting going on here that I can tell. This is maple ply

335685
This is one I did on baltic birch using that process:
335734

[Raphael Weil]

Yes, this looks like it was stained after engraving to darken, as you can see the bleeding into the grain. I get that result when I engrave and stain the lasered area. That's a method I use often, but the sanding doesn't always get all of the bleeding out. What I'll often do to minimize the bleed is to engrave, sand, sealcoat, then stain the engraved area. I'll use Restor a finish (dark oak) for the stain. It looks natural, and works pretty well.


This is one I did on baltic birch using that process:
335734

Curious how you stain just the engraved area (I gather the sealcoat is spray on everything before?). Do you just wipe off the stain from the non-engraved area and let the engraved area retain the stain? Thank!

[Bert Kemp]

yes just wipe off the stain the engraved area will hold the stain the finished area will wipe off.

[Don Corbeil]

yes just wipe off the stain the engraved area will hold the stain the finished area will wipe off.

Yes, exactly. The sealcoat will allow wiping off the finished area, and helps to minimize bleeding from engraved area into the grain.
I will use both spray (zinnser dewaxed shellac) or brush on liquid.

[Samuel Espy]

...What I'll often do to minimize the bleed is to engrave, sand, sealcoat, then stain the engraved area. ....


Don, what is your reasoning behind sanding after engraving rather prior to it as part of a surface preparation process? Is the purpose to remove engraving smoke/residue or something else? I am certainly not being critical. Your beautiful work speaks for itself. I just suspect there is something that I am missing that might prove useful. I, like everyone else, have spent time trying to develop a repeatable, inexpensive, yet quality process for darkening wood engravings (particularly photo engravings). I have had the best luck with 1) preparing surface (sanding, clearcoat and often wax), 2) apply transfer tape, 3) engrave, 4) spray lacquer (helps avoid bleeding) 5) spray paint with several very light coats of brown flat paint, and 6) remove transfer tape with plastic razor blade. It produces good results when done carefully. However, a very discerning eye still might perceive the paint in the engraving.

You note in a later post that you use "zinnser dewaxed shellac" as your sealcoat. Is this this product (http://www.rockler.com/zinsser-bullseye-sealcoat). If so I am confused as to why the stain does not darken the non-engraved areas which i think from your description are only coated in this sealcoat. It seems the purpose of this dewaxed shellac is to allow all stains to stain beneath it. Does it not stain the non-engraved areas because you wipe on and off fast or something?

I would much rather use a stain as you describe as it looks more natural, but previous efforts have always had unacceptable bleeding. I am amazed at how little bleed you have in the beautiful engraving of the dog (St. Bernard?). Maybe I will try your stain and sealcoat. Do you not seal the complete surface with clearcoat prior to engraving? I am surprised that the stain does not darken the non-engraved areas in addition to the engraved areas since if you do not clearcoat both areas are only coated with sealcoat.

Thanks in advance.

[Don Corbeil]

Don, what is your reasoning behind sanding after engraving rather prior to it as part of a surface preparation process? Is the purpose to remove engraving smoke/residue or something else? I am certainly not being critical. Your beautiful work speaks for itself. I just suspect there is something that I am missing that might prove useful. I, like everyone else, have spent time trying to develop a repeatable, inexpensive, yet quality process for darkening wood engravings (particularly photo engravings). I have had the best luck with 1) preparing surface (sanding, clearcoat and often wax), 2) apply transfer tape, 3) engrave, 4) spray lacquer (helps avoid bleeding) 5) spray paint with several very light coats of brown flat paint, and 6) remove transfer tape with plastic razor blade. It produces good results when done carefully. However, a very discerning eye still might perceive the paint in the engraving.

You note in a later post that you use "zinnser dewaxed shellac" as your sealcoat. Is this this product (http://www.rockler.com/zinsser-bullseye-sealcoat). If so I am confused as to why the stain does not darken the non-engraved areas which i think from your description are only coated in this sealcoat. It seems the purpose of this dewaxed shellac is to allow all stains to stain beneath it. Does it not stain the non-engraved areas because you wipe on and off fast or something?

I would much rather use a stain as you describe as it looks more natural, but previous efforts have always had unacceptable bleeding. I am amazed at how little bleed you have in the beautiful engraving of the dog (St. Bernard?). Maybe I will try your stain and sealcoat. Do you not seal the complete surface with clearcoat prior to engraving? I am surprised that the stain does not darken the non-engraved areas in addition to the engraved areas since if you do not clearcoat both areas are only coated with sealcoat.

Thanks in advance.

Samuel, thanks.
Yes, I do sand after engraving to completely remove the residue and prepare the surface for sealing. The sanding also lightens up the portions that are not engraved, increasing the contrast. I may seal with zinnser a couple of times until I get a good coat, and like you, I sometimes use a lacquer for woods that tend to bleed. I then stain (restor-a-finish dark oak) and make sure I wipe off the stain IMMEDIATELY from the un-engraved portions of the piece. If I still get excessive bleeding, or some stain going through the seal, I will light sand again to try to clean and lighten it up. The key for me is that I may go through a few cycles of staining and sanding to get the contrast I want. When I get there I then lacquer finish the entire piece.


I haven't tried the transfer tape method for engraving photographs, does this tape seem to work OK for photoengraving?

[Samuel Espy]

Thanks for the clarifications, Don. In my experience, one of the keys for using transfer tape as a masking technique when engraving photos is to engrave deep enough into the wood such that the transfer tape adhesive is vaporized away. Otherwise, the paint or whatever you plan to use as color fill will obviously not adhere to the engraved areas of the wood.

[Bill Reibelt]

I Varnish all of my timbers before lasering or CNC carving. This allows the area lasered to be paint filled or painted with out bleeding.

[Klaus Madsen]

Lee's right, I also ran into this on a book (Journal) cover that was very light tan thin leather. I burned the lettering into it and the lady wanted it deeper. The next pass was into the hardboard underneath that happened to be black so it worked out nicely.
I do that all the time, and I lower the speed and power. But I have to say that I really would like it darker, nearly black.
I know the numbers are different for all machines but on my 100w Redsail I run engravings at 1oo mm/s and around 16% power.

[Bert Kemp]

What are you engraving "Leather? Try increasing your speed and your pwr and take it out of focus about 1/8 inch.


I do that all the time, and I lower the speed and power. But I have to say that I really would like it darker, nearly black.
I know the numbers are different for all machines but on my 100w Redsail I run engravings at 1oo mm/s and around 16% power.

[Glen Monaghan]

I've done the same defocus trick for cardboard and it does help get a darker result without burning through, but it made for a "softer" image. If someone is expecting crisp lettering or details, taking the beam out of focus may get the engraving darker but is going to disappoint them on the reduced details.