Baltic Birch - How to darken engraved areas on Baltic Birch

[Roger Lueck]

I'd like to be able to get darker engravings on Baltic Birch at 300 mm/sec speed without masking/painting or color filling. I've tried increasing the power which increases the depth of the engraving but does not change the darkness of the engraving much. I currently use a BLO/Poly/Mineral Spirits mixture for a finish which is applied and allowed 24 hours dry time before I engrave. I also use 3-5 lb of air pressure in my air assist while engraving.

Is there another method of a type of finish that will cause a darker burn in the engraved area?

Thank You,
Roger

[Matt McCoy]

Do you have a pic of current results?

[Mike Null]

Try running your engraving out of focus by 1/16 to 1/8 inch.

[Matt McCoy]

These are the typical results I get engraving BB:

[Roger Lueck]

Matt,

Thank you for your reply and the photos. What you show in your photos is the typical results I get with a speed of 150 mm/s. I'm trying to increase the speed to 300 mm/s and maintain the same results as at the slower speed (150 mm/s) but have not had any success.

Roger

[Roger Lueck]

Mike,

Thank you for the suggestion, I will give it a try as I have not used "out of focus" in any of my tests due to the small lettering that needs to be clear and crisp.

Roger

[Robert Bonenfant]

Hey Roger ,

try a series of test with different power levels. Not sure what power your using - I would think as you increase speed - you have to change the power in comparison. I really think if you do some test with different power levels you'll get the results you need. Also what machine are you using ?? We use 30 psi area and it tends to blow out the area really quickly - this might help.

[Roger Lueck]

Robert,

Thank you for the response. I've done considerable testing by developing a grid based on power and speed.

From that testing I determined that at 300 mm/s, increasing the amount of power did not appreciably darken the engraved area, it only removed more material (deepened the engraved area).

My goal is to find a way to darken the engraved area at a speed of 300 mm/s to the level of darkness achieved when engraving at 150 mm/s and 30% power.

Mike Null suggested in his contribution above to move the lens so that it is out of focus .0625" - .125" which should darken the engraved area (I will try that tomorrow), however, it may also result in the loss of clean lines and crisp text in the smaller fonts.

Increasing the PSI of the air assist does not darken the engraved area, it tends to cause more material to be removed resulting in the degradation of fine details of an image and text.

My hope was that there may be a "finish" I could apply before engraving that would cause the engraved area to darken (burn) while engraving at 300 mm/s (speed) without significant loss of detail.

Roger

[Bert Kemp]

could we get a picture of what your doing. Sounds like your engraving letters. Have you tried vector engraving also out of focus. I vector engrave letters at 325 to 350 mmps and 35 to 40% pwr they are pretty dark

[Glen Monaghan]

In order to get bb dark when engraving, you have to "toast" the wood, not ablate it. From your current power and speed settings, simply adding more power won't darken more, it just digs deeper (as you found). When toasting the wood, you have to avoid overpowering it with too much energy, and that means you either have to "go low and slow" (slow down to lengthen the time a given spot of wood gets exposed to the beam, and lower the power so as to toast/char/caramelize/whatever-you-want-to-call-it the wood without vaporizing it) or defocus so that the beam energy is spread over a larger area than normal, thereby allowing you (at least theoretically) to up power and speed. My experience is that low and slow it the only viable way to darken the bb that I typically get. Once in a great while I've had a piece that got great contrast, but what you are getting looks about par for the course with bb...

As an alternative, if you pre-finish your wood, you can try something like laserdark spray or simply wiping on liquid shoe polish, but only if you have a good finish!

[Don Corbeil]

Here is a sample of one of 54 8x10 portraits on BB I did for our local kennel club awards show recently. And as Glen says, 'toasting' the wood is the operative word here. It's hard to specify what power and speed combination gets me there, because the baltic birch varies from batch to batch and even piece to piece. I will usually do a first pass with a lesser power, see how that goes, then burn much darker on second pass. Yes, two passes (or more) takes more time, but I want quality results not speed.
DSC03274 cropped.jpg

DSC02959.jpg

[Roger Lueck]

I'd like to thank everyone for their replies. I achieved getting a darker burn using the "out of focus" method mentioned in a couple of the replies above, although, the graphics and lettering were not as crisp.

Thanks to every one, I appreciated your responses.

Roger

[Gary Hair]

I want quality results not speed.

I've been doing this for 11 years and those are some of the best lasered photos I have seen!

[Don Corbeil]

I've been doing this for 11 years and those are some of the best lasered photos I have seen!

Gary, thank you for the compliment!

[Mike Null]

Don

I'm with Gary. I detest engraving photos on wood (or anything else) but your results are definitely the best I've seen. Magic !!