Stainless Cermark loss of fills

[Patrick McCoy Arkansas]

I know this has been discussed several times, but I've got follow up questions to some of the answers I've found...
My art is through CorelDraw X6. Mostly raster designs
Laser is a 60W Epilog Legend 36EXT
Laser is recently cleaned and alligned
Settings are typically 600 DPI, 100power 35-40 speed Dithered as standard or Jarvis
Cermark LMM 6000 in the can

Attached photos are Test runs, Decent results and poor results

I understand that some larger black fills tend to have issues from probably Higher temps being generate.

1. When a design is mostly simple lines with a couple of decent fills, is there a way to compensate to a happy medium?
2. Possibly more importantly, can you tell a difference in degradation, due to Too much heat vs not enough? I feel like the "not enough", whether it's due to application of cermark, or settings, tends to "smear" off and when it's too hot, it tends to speckle off? If you know, I'd appreciate it, because at times when it smears, I slow it down and it improves, but then one time it will reverse on me and I just don't know if I'm chasing the rabbit down the correct hole or not.
3. Is there anything I can do to the design that might help? The main logo I have regular issues with, when I'm doing the 1.5" version, it runs 95% without issues. When I'm running the 2.5" design, my success drops to maybe 75% success.

Thanks for any additional thoughts.
PatrickIMG_2616.jpgIMG_2613.jpgIMG_2618.jpgIMG_2624.jpgIMG_2614.jpgIMG_2616.jpgIMG_2613.jpgIMG_2618.jpgIMG_2624.jpgIMG_2614.jpg

[Gary Hair]

I'd say it's about 99% that you have an uneven coat of Cermark and that is causing the problems. Underpower results in Cermark not sticking, true overpower results in a tan color instead of black - I'm not seeing tan or anything remotely close to it. Spray cans are horrible for getting the thin, even coat that you really need for consistent results. Ditch the spray can and either use a foam brush or an airbrush - I guarantee you won't see the problems you are now. Oh, and just a tip - for speed testing use a 1/4" square, it will save tons of time vs the big patch you are using now. Once you have the thin, even coat, 1/4" will be plenty to determine the correct settings.

[Mike Null]

Gary beat me to it. I think it's your application and preparation. It is very easy to apply a thick coating with the spray can.

Your settings appear to be in line with what I'm using.

[Jeff Body]

This may be a lack of terminology since I don't have an Epilog.

Why are you using a raster design for what's pictured? Why don't you vector it and run it as a vector engraving?
I've never had much success with cermark and a dithered design. That's why everything I do with cermark is a vector design.

[Kev Williams]

Just me, but I have never had "too thick" be a problem. and I used a can for several years before air and foarm brushing. The reason may correspond with my next thought--

Engraving speed. Not sure of your actual 35-40% speed, but for every RF laser I'm familiar with, that's too fast for Cermark, even if you have the extra power. It's a matter of heat soak, Cermark needs a little time under the beam. The FASTEST I can reliably run Cermark with my LS900 is 18%, and that's at 600 LPI-Y/800 DPI-X resolution. If I drop the Y to 500 lines, then I have to drop the speed to 16%.

I can almost guarantee better results if you slow down to 20% and lower your power to about 75%.

As for prep, my question is, how are you cleaning them before applying the Cermark? Almost EVERY TIME I've had Cermark end up like the pics, it happened on SS I forgot to wash off first. I've found that what you use doesn't matter much. I grab whatever's handy, usually Windex or alcohol. Acetone is fine but isn't better or worse, same for Fantastik or anything else. It just needs to get any surface dust and oils from your hands off.

And I know some people mix or thin Cermark with water, but in my experience, water and Cermark = bad results. I washed out an airbrush bottle with water once awhile back, and after airhosing the jar dry, there were still little droplets of water inside- I figured no harm, but the parts I engraved with that batch, the Cermark didn't stick... the ONLY liquid that touches my Cermark is DNA or Everclear...

-- I'm wondering if focus is an issue, but some of the bad I notice is in the middle of the engraving where focus should be the same as elsewhere.

Slow the machine down is my prime advice. Nobody wants to hear that, but there's no such thing as engraving Cermark quickly...

[Gary Hair]

Just me, but I have never had "too thick" be a problem. and I used a can for several years before air and foarm brushing. The reason may correspond with my next thought--

Engraving speed. Not sure of your actual 35-40% speed, but for every RF laser I'm familiar with, that's too fast for Cermark, even if you have the extra power. It's a matter of heat soak, Cermark needs a little time under the beam. The FASTEST I can reliably run Cermark with my LS900 is 18%, and that's at 600 LPI-Y/800 DPI-X resolution. If I drop the Y to 500 lines, then I have to drop the speed to 16%.

My Trotec does best at 25% speed and 600 dpi.

I can almost guarantee better results if you slow down to 20% and lower your power to about 75%.

Speed is completely dependent on the machine and there is never a reason to go below 100% power with Cermark.

As for prep, my question is, how are you cleaning them before applying the Cermark? Almost EVERY TIME I've had Cermark end up like the pics, it happened on SS I forgot to wash off first. I've found that what you use doesn't matter much. I grab whatever's handy, usually Windex or alcohol. Acetone is fine but isn't better or worse, same for Fantastik or anything else. It just needs to get any surface dust and oils from your hands off.

Denatured alcohol is really the best thing to use. Everything else you mentioned will leave a residue and can cause the Cermark to not adhere. It may work for you but you have too many variables to consider for the times it doesn't work.

And I know some people mix or thin Cermark with water, but in my experience, water and Cermark = bad results. I washed out an airbrush bottle with water once awhile back, and after airhosing the jar dry, there were still little droplets of water inside- I figured no harm, but the parts I engraved with that batch, the Cermark didn't stick... the ONLY liquid that touches my Cermark is DNA or Everclear...

Thermark is thinned with water but never Cermark.

-- I'm wondering if focus is an issue, but some of the bad I notice is in the middle of the engraving where focus should be the same as elsewhere.

Focus could be an issue but based on his description I'm still going with prep and application of the Cermark being the issue.

Slow the machine down is my prime advice. Nobody wants to hear that, but there's no such thing as engraving Cermark quickly...

You normall give good advice Kev but this time I think you missed the mark. The only way to know the settings for Cermark is to do a test grid and go with the settings that work best for your machine and the particular substrate you are using. Simply slowing down the machine isn't going to resolve anything, especially if the prep or application is the real problem.

[Keith Downing]

I think others have covered pretty much everything, but here is my process and I have exceptionally consistent results.

Nothing has ever flaked off or come out discolored since I've started doing it this way.

-- Wet a rag with Denatured Alcohol and wipe each surface before cermark application
-- Apply cermark so that all of the metal surface to be lased is covered. How thick it goes on almost never matters IHMO. The one exception would be if you are putting it on SO thick it's ridiculous, that might block some of the laser power. But I haven't found thin to be a problem yet.
-- Let dry AT LEAST 30 minutes. Longer if it is a humid day.
-- Upload design with .08 to .10 scan gap. That's on a chinese laser, but I think it should be about 300-600 dpi.
-- Make sure the cups are level on the rotary tool, and focus is spot on.
-- Laser with ample air. I use an external compressor and usually work around 20psi, but up it to 30psi if the design has large solid areas. This is very important IMO.
-- My settings on a 60 watt chinese laser are usually pretty close to 200 mm/s and 80 power.

[John Lifer]

I've hit a sweet spot so far on my chinese, 65% power on my 80 watt and 165mm/s Yes it is slow, but nothing comes off, more power at that speed and I warp the cup, I should probably run up to 185-200mm/s, but it works, and I'd rather lose a minute than lose a cup and the time to run it. I brush, if I don't leave a streak, it is a good black and ALWAYS clean with DNA. I don't always let the LMM14 set 30 minutes, but usually 15 or so and run with air also. I'm in a usually dry area, so things don't take too long to evaporate.

[Mike Null]

Kev
I think the speeds you are comparing might be apples and oranges. I run mine at 17% but an Epilog would run at about twice that due to the difference in raster speed.

[Kev Williams]

me:

Not sure of your actual 35-40% speed, but for every RF laser I'm familiar with, that's too fast for Cermark, even if you have the extra power.

Epilog is pretty coy about publishing engraving speeds, but Patrick's machine does use servo motors, and those are typically good for at least 80ips engraving speeds (like the old GCC), and 40% of 80 is 32" per second. Too fast. I just spent a few minutes running some time tests and my LS900 at 18% speed covers almost exactly 13.3" per second. (338mm/sec) If I engrave faster than that, I'm asking for trouble. More than my 40 watts may help with getting away with higher speeds, but Cermark needs dwell time. Even Cermark says so. 20 or 30" per second is simply too fast.

^^ my opinion, but it is based on 15 years of experience...

As for Windex not working, then don't use it. I love it, because that film it leaves behind gives something for Cermark to adhere to. I laser etch knives for a guy so highly polished that Cermark just balls up and rolls off like it's mercury. A little Windex and the Cermark sticks. And not once ever has Cermark-over-Windex failed. But to be fair, it hasn't failed with DNA either --

And Gar, I brought up prep in my first post, and I agree slower won't fix bad prep.

But I gotta disagree a bit with 'there is never a reason to go below 100% power with Cermark'-- RF lasers, to a point yes, as I can't overcook Cermark with mine or your old machine. But the Triumph is a whole nuther animal...
These pics mostly speak for themselves, and I'll explain why I simply can't Cermark SS with this machine...

I ran them as they state, 180mm/sec and only 25% power top line,
and full 500mm/sec speed at 80% power second line (80% is probably hitting 90 watts in the long areas).
gap is .05, approx. 500 lines per inch..

Even before rinsing, line 2's Cermark is history. Heat soak isn't an issue, brutal power is
ck1.jpg

Line 2 is basically roasted SS.
Line 1 looks pretty good actually, I ran it low and slow just to show that heat soak does work. And it survived the scotchbrite test just fine.

ck2.jpg

Nice & black to be sure, but---
check out how the Cermark is overcooked in the LONG expanses;
top & bottom of the E, top of the T, middle of the A, even the center section of the S slightly...
-- I can't sell engraving that looks like this (or like line 2)
ck3.jpg
ck4.jpg
ck5.jpg

This anomoly is this machine's Achilles heel, and I can't figure out a fix. No matter how slow or fast or the power used, I get those stripes. If I lower the power, then the reverse happens; the long stripes get better but the short areas don't stick. But only with stainless. This machine puts Cermark on brass and aluminum perfectly...

Sorry if I came across as argumentative, it's just things work at my place. Your place may differ

[Keith Downing]

Every machine has its differences, that is for sure.

Kev, if you don't mind me asking, how much air are you using when you go with the higher power? Does it not make any difference at all?

Also, that's interesting about the Triumph. Does it run on a different wavelength than a standard CO2 tube.

[Patrick McCoy Arkansas]

Keith, I'm not familiar with the term "Scan Gap"... I think that I can guess... Would "dithering" be a concept? Or when you say "upload design", i'm not sure what I would change in the design for Scan gap. I use Corel and simply input the design by "Printing" to my epilog and then tweak the settings in the print parameters of the Epilog print software?

[Keith Downing]

Scan gap is essentially the Chinese machine's equivalent of DPI. The smaller the number, the more passes the laser makes in the process of completing a raster design. It is literally the gap between x axis scans (passes from left to right).

With a western machine my understanding is you are working in dots per inch in most cases. So just make sure you have a high enough quality image to start with, and that your settings result in a comparable number of passes with your laser.

[Kev Williams]

one of my pet peeves is manufacturers referring to Y-axis raster movement in DOTS per inch. Only time it's dots is when an RF laser is vectoring.

And for what it's worth, and to the best of my knowledge,
most if not all RF fired lasers fire in the X axis like this ..........................................
and
most if not all DC fired lasers fire in the X axis like this __________________________

-an RF laser is ALWAYS pulsing, and a DC laser is NEVER pulsing...
--in most cases, as I understand it...

but when rastering, the Y axis doesn't lay down DOTS, it lays down LINES!!