how to get a black color on the bottom of a cut.

[Steve knight]

I have some baltic birch and the letters will be pocketed out but the customer was not happy with the job the laser place did the bottom of the letters were not dark enough. I don't think the company knows how to get that color any idea's on what to tell them?

[Dan Hintz]

Several ways... go out of focus, lower the power and slow the speed down, reduce the ppi, etc. The laser shop should really know how to do this, though... if they don't, you should consider using a shop that understands their machine.

[Glen Monaghan]

If you don't want to color fill or add dye to the engraved areas, then you need to have the laser heat up the engraved areas enough to darken, almost char, without vaporizing the wood. Dan described ways to do that: low power and slow speed, out of focus.

-Glen

[Mike Null]

I wouldn't be so sure that you can achieve the dark contrast you're after. It is not necessarily a matter of skill. Some woods do not provide good engraving contrast, particularly white woods such as birch and maple. I would experiment with slower speeds even if you have to lower the power to avoid burning too deeply and above all, run the job at the highest dpi setting. That will cause the machine to engrave at a much higher density thus providing a better burn.

[Tim Bateson]

Ditto. If you think power & speed is the only answer, than you haven't done enough engraving to know better. Some woods are perfect for lasering, others are not. I've lasered many woods that will not burn/char well. Either sporadic grain differences or not at all. In those cases I use a powder paint or acrylic paint. If the wood is going to be stained that can also add a great contrast within the engraved areas.

[Rodne Gold]

Actually , if the laser is working the way it should , you should get no burn at all IE complete vaporisation with no heat affected zone. The easiest way to get colour or darkness with low resin woods *its the resin that "stains" it* is to laser thru a mask like self adhesive masking tape and then stain or spray the exposed lasered surfaces and remove the mask after...assuming the stian/paint doesnt bleed.

[Glen Monaghan]

Not sure if you guys just misread me but I agree with what Mike, Tim and Rodne say about trying to get enough darkness, which is why I started off with "If you don't want to color fill or add dye..." But, if you _don't_ want to use color fill or dye, then reducing the beam intensity enough to cause heat discoloration without vaporizing the wood is the only hope of getting good contrast (but not a guarantee, as Tim notes). I engrave a fair bit of oak and I don't think it darkens enough, plus I don't care for the way the darkness varies so dramatically between alternating grain layers, but the customer loves it so I'm happy enough with it. I've found cherry to be very good for engraving easily and with good contrast. On the other hand, I was trying to make some 1/32" ply bookmarks with a lot of finely detailed markings and the wood had such poor contrast that it tended to burn through at the lowest power/speed combination I was willing to mess with, so I still need to try making up my own ply from a "better" species of veneer.

-Glen

[Rodne Gold]

Seems customers like lasering more when it does a messy job on wood , the more it looks like its been branded on the better - smoke damage , char and all. Difficult to intentionally mess up to make a job more appealing.

[Steve knight]

thanks everyone. I did not pick this company this was a three part job. I cut the maple discs and vcarved them and sent the rest of the design to my customer who went with the laser guy. I have heard the company does not really know a lot about their machine though.
this job did not make them happy the end customer was complaining about the fuzzy letters I did and that the engraving was not dark enough.

[Joe Hillmann]

Steve,

Maple will not engrave dark unless you go out of your way to make it dark, either by dying/painting or over powering it. Usually the darker the wood the more contrast it has. I think the reason for that is the darker wood absorbs more of the energy from the laser as heat and it chars more whereas the lighter woods don't absorb as much so you are vaporizing it before it gets a chance to char.

Also I am curious, did the customer have any samples done so he would know what to expect?



Rodne,
I have found that people like the wood to look rough and it really bothers me to produce work with smoke stains when I know I can make it perfect. They call it "rustic", I call it a job, but it's what they want.