Full Version: Help with painted brass
From: Bill (BILL_S) [#1]
26 Mar 2007
To: ALL
I'm trying to laser some black painted brass (black over brass) that I bought from JDS and which they claim is laserable. I'm using a 35 watt ULS and I'm lasering vector clip art. I've experimented with the settings and the optimum seems to be 33 power at 100 speed using 500 ppi.
After I have finished lasering, there is a residue that I have to wipe off. But even then, the brass is dull looking instead of a rich, shiny look. In fact, if I scratch the brass, I get the shiny look that I want -- but I just can't seem to laser down to it. Is there a solvent that I should be using to clean the painted brass with after lasering? Or do I need to experiment with the laser settings some more? I have tried multiple passes and that doesn't seem to work either.
I don't have a rotary or any other type of mechanical engraver so I really need to figure out how to do it with the laser. Or is this the impossible dream?
Oh yeah, there are diaginal bands running from the lower left to the upper right. This is the least of my problems at the moment, but maybe that will give somebody a clue as to what is going on.
Thanks for the help,
Bill
From: Stunt Engraver (DGL) [#2]
26 Mar 2007
To: Bill (BILL_S) [#1] 26 Mar 2007
Bill,
Sounds like the brass may not be the laserable variety. Laserable brass is polished, before it's coated with black.
Standard black brass (for rotary/drag) isn't polished before it's black-coated. The diamond gravers and burnishers provide the "shine."
EDITED: 26 Mar 2007 by DGL
From: Bill (BILL_S) [#3]
26 Mar 2007
To: Stunt Engraver (DGL) [#2] 26 Mar 2007
Thanks David,
That's probably it. I've never used painted brass before so I didn't know the difference -- other than in the catalog it specifically said that these items were laserable and they had other items in the same "class" (keyrings) that didn't say that they were laserable.
I guess that I will quit beating my head against the wall, send them back, and try something else.
Thanks again,
Bill
From: Harvey only (HARVEY-ONLY) [#4]
26 Mar 2007
To: Bill (BILL_S) [#3] 26 Mar 2007
After lasering a sample, try blackening the engraving. If it blackens, it is NOT laser brass. Laserable brass may be a word trick to make it seem like the laser brass but it is not necessarily so.
Laser brass is polished, then clear coated, then black coated. This gives it a high shine when lasered. It makes the surface slightly easier to scratch.
Black brass is just black coated. The surface of the brass is NOT high polished which gives the paint a better grab.
From: Bill (BILL_S) [#5]
26 Mar 2007
To: Harvey only (HARVEY-ONLY) [#4] 26 Mar 2007
Harvey,
Since I only do laser engraving, I don't have any oxidizers or blacking agents around. However, now that I am getting "smarter", I'm pretty sure that I don't have laser brass but laserable brass (whatever that is!). In fact, now that I look back at the key rings that I have already done, I see where the brass is tarnishing from my fingerprints. I ran some samples at 10 power and 100 speed so I'm pretty confident that I am not blasting through any clear coat that might have been there.
I am getting ready to call JDS and see what they have to say.
Thanks for the help and advice.
Bill
From: Mike (MIKEN) [#6]
26 Mar 2007
To: Bill (BILL_S) [#4] 26 Mar 2007
Not all laserable brass is created equal. On some I have to use 1000dpi setting to clean it up.
Even with that I use auto polish on all pieces to get a good shine.
From: Bill (BILL_S) [#7]
26 Mar 2007
To: Mike (MIKEN) [#6] 26 Mar 2007
Mike,
I was using the 10 power, 100 speed as an example of low energy that shouldn't have gone through the clear coat if it was there.
Before I asked for help here, I tried a matrix of various power and speed settings including 100 power and 10 speed. I ever made three passes at high power and low speed. And three passes at low power and high speed. And I tried 1000 ppi and 250 ppi (on both axises). In all cases, the results were unacceptable to me and something that I would not show my customers. Luckily, these were going to be done for impulse sales rather than for a customer order so it is not a disaster. I originally was going to do them out of wood, but stumbled across the metal ones in the JDS catalog and thought that they would have a little more "curb appeal". Looks like I will be going back to the wooden ones.
Thanks for the suggestion though.
Bill
From: John (ICTJOHN) [#8]
26 Mar 2007
To: Bill (BILL_S) [#1] 26 Mar 2007
Bill,
If you are using laserable brass and there was not a mixup from JDS or the factory, I see 2 clues that says you probably are using too little power.
1. If you have a residue left on the sheet after lasering, you are using too little power, the laser should vaporize that black paint. (you are probably seeing a true "flame" instead of a bright white spot)
2. You are running a 30 or 35 watt machine (your profile and your message show 2 different wattages) at 100% speed at 33 power, again too low for this substrate. Probably reversed your settings like was previously mentioned.
fyi, if you bought the laserable metal from JDS, it should say "laser" on the back where the time stamp is printed.
hth,
;-)
~
EDITED: 26 Mar 2007 by ICTJOHN
From: Bill (BILL_S) [#9]
26 Mar 2007
To: John (ICTJOHN) [#8] 26 Mar 2007
John,
Being filled with self doubt after you and Mike said basically the same thing, I lasered another one. Started at 80p and 25s. I can adjust the settings on the fly so I usually engrave a rectangle and adjust the settings while engraving to see differences. On this run I ran the power up to 100 while holding the speed at 25 and then ran the speed down to 5 while holding the power at 100. Never got a good result.
I did see flame at all settings until I moved the speed below 10. Below that, the flame disappeared. But so did any economic incentive to do key chains :S .
These are key rings that are already fabricated -- not sheets -- so there is no marking on them at all. They are individually packed in reclosable bags that say "Made in Taiwan, R.O.C."
I will update my profile. It is 35 watts (but what is 5 watts among friends :D )
Bill
From: John (ICTJOHN) [#10]
26 Mar 2007
To: Bill (BILL_S) [#9] 26 Mar 2007
probably $1,000 - $2,000 :O)
Sorry, to hear they were not laserable.....
~
From: Harvey only (HARVEY-ONLY) [#11]
26 Mar 2007
To: Bill (BILL_S) [#9] 26 Mar 2007
It is almost impossible to laser off the clear coat. I have tried many low speed and high power passes but it hardly touches it.
If you can see fingerprint tarnish, it is not clear coated.
You can get it brighter by using the #2 Novis plastic cleaner. It is a super fine abrasive that works well. Then use a good wax to reduce future tarnish.
[I have to find a polish that still contains carnuba(sp?) wax.]
From: Bill (BILL_S) [#12]
26 Mar 2007
To: Harvey only (HARVEY-ONLY) [#11] 26 Mar 2007
Harvey,
Thanks for the tip. But I was planning on engraving about 150 key rings to have on hand and sale as "impulse" items when people saw them. If I needed to do one or two or three trophy plates -- or something similar -- it might be worth the extra effort to polish, wax, etc. But in this case if they can't be done "quick and dirty" it really isn't worth it. At least, not to me.
Bill