Is metal marking paste necessary?

[Bob Davis]

These photos show direct lasering (no paste) onto stainless steel using a GCC Mercury 25 watt. The lighter image was made using 100% power, 10% speed and 600dpi, while the dark used 100/4/1000.
This particular tube (Synrad) seems to be a particularly good one for power, but I also think there may also be a fortunate coincidence involved with the optics producing a spot which is close to optimal. I recall having read elsewhere that around 50 watts is the usual minimum required to mark stainless, and 100+ for reasonable speed.
The mark itself seems very similar to one produced with metalmark paste.

My questions; Do other 25w machines produce similar results? Any drawbacks (other than slowness) in using this method? Anybody have any experience with its permanence/UV stability/suitability for use?

[George Elston]

I recently did a job on stainless, and gave the customer the option with 2 samples, one with cermark and one direct marking. The cermark took one minute, the direct marking four, at a dollar a minute for a commercial size run, the customer chose the cermark. But can I mark directly on Good American Stainless with a 30 Wt laser, yes. It just takes longer.

[Vicky Orsini]

I recently did a job on stainless, and gave the customer the option with 2 samples, one with cermark and one direct marking. The cermark took one minute, the direct marking four, at a dollar a minute for a commercial size run, the customer chose the cermark. But can I mark directly on Good American Stainless with a 30 Wt laser, yes. It just takes longer.
Wouldn't the cost wind up being about the same, once you factor in the cost of the Cermark?

[George Elston]

The cost of the cermark is practically negligible, sure it's expensive, but I put a bit of cermark the size of a pea in the airbrush bottle and thin it to nothing. You will see different opinions but I probably thin 20 or 30 to 1, i.e. fill 1 oz. bottle 1/2 full with thinner, (DA or acetone). Less is more with the stuff. I can't tell you how much this covers, but I don't refill the bottle very often. The biggest problem I had with the stuff is using too much, too thick a coat and it wipes right off, I like to try to get it one grain thick, one pass with the airbrush and thats all. I need to look close with a good light to see that it's there, just dull the surface. Definitely not an extra $3 per piece, more like 3 cents.

The only advantage I could see would be in prep time. On the job in the picture I spent way more time cleaning the steel than marking (spoke to customer about providing production ready blanks, not greasy grimy stuff). If I was marking right on the steel that wouldn't have been a problem.

[Eric Allen]

I've noticed some leeching/smearing issues with using just a CO2 laser on stainless. It comes with water exposure. There is a bit of discoloring around the areas. I'd say if you have any likelihood of water exposure, which is most stainless products, I'd go with the marking compound. The marking compound doesn't have the smearing issues and doesn't seem to change the metal properties. If anything, it appears to protect it.