We have had some customers report to us in the past that they have seen CerMark fade over time in outdoor applications. We have also had customers report to us that they have made signs, plaques or memorials that are outside that still look as good as new with several years of exposure. We have had people also report results that were anywhere in between....
We have done testing at our lab with marks exposed to QUV (UV radiation test that simulates exposure to the Sun), Salt Fog, and actual exposure on our factory roof (South Western PA., a mix of all seasons). What we have found is that resistance to fading/exposure can be linked to a couple of factors:
Metal being used.
The metal used can play a role in exposure resistance. We have found that marks made on better grades of stainless steel survive better than marks on cheaper grades. The 304 is the most common grade of stainless and manufactured in both a low carbon and a high carbon grade. (304L and 304H) The high is most common, but the low carbon grade has much better resistance to corrosion and fading. 316 (also in low and high carbon grades) is even better, it is commonly used in situations where there will be exposure to marine environments, like salt water. 316L is best for these applications.
Power settings used to make the mark.
The power settings used will also play a role in the resistance to fading. LMM-6000 will make a black mark at a wide range of power settings, but not all of those marking will perform in the field the same way. We always recommend getting a test piece of metal and performing a test power grid on it before marking the job. To do this you would make a series of small blocks on the piece. Make all of the blocks at 100% power and then vary the marking speed. After looking at the grid, you should be able to see a point where the material begins to bond, a few marks that are black, and then a point where the heat generating was to high and the marks begin to turn a bluish-grey. The bluish grey marks are an indication the mark is to hot, you probably will even begin to feel a dimpling of the metal at that point. The optimum power settings for that part will be at the point just before this begins to happen. These marks will give the best durability.
Cover the mark with a clear coat.
The technique of clear coating marks is a very good insurance policy for fading, and it does increase the blackness of the marks. We can recommend fluoropolymer coatings from Shield Products and Steward Systems below. These kind of coatings are used all over Disneyland on their outdoor structures. Marks not covered my look more gray over time but come back to black when washed with water.