durable, hard-use, gold color fill

[Glen Monaghan]

About a year ago, I laser-engraved the handles of several knives for someone. The engravings are essentially line drawings and text, no thick/wide engraved areas at all. He liked the look on the wood handled knives where the engraving was a bit darker and into the wood, but the black-on-black engraving on black micarta handles was hard to see unless turned in direct lighting to create shadows in the engraving.

The knives have golden colored brass rivets, so I tried color filling with a matching gold. That made the engravings "pop" and the guy was very pleased with the look. We first tried Rub-n-Buff but that quickly discolored, picked up dirt and grime from using the knife, and even seemed to ooze back out when it got warm. Next tried acrylic paints and they lasted a bit longer but not much before discoloring with use. I then tried an enamel gold paint and it seemed like it was going to work, but my sample has darkened noticeably over time and he called to say that the knife he uses frequently has no gold color at all anymore. My sample brightened back up when I wiped it with acetone so I've asked him to wipe it with solvent to see if the surface is just very dirty or if the paint is actually gone and needs to be replaced. He's going to check on that, but the idea of requiring annual color replacement or requiring periodic solvent wipe down wasn't acceptable.

As an experiment, I tried coating the fill with a couple of different clear substances like epoxy and superglue. The quick set epoxy didn't flow well and was too thick, while slow set epoxy took too long, was still noticeably thick, and the thin edges where I tried to feather out the epoxy didn't wear well in either case. Thin superglue didn't flow evenly over the engraving and left a broad shiny patch look; trying to smooth it out and remove the excess with solvent after it hardened made a growing mess.

I asked a couple of laser goods suppliers how to handle this; both said they'd never had demand for such a thing and had no ideas for where to turn... I'm wondering if there's something like a gold colored epoxy that can be used for the color fill that is very durable and non-oxidizing? Might the paint used on stone monuments work for this (assuming there is a matching gold color)?

Bottom line is, does anyone have any suggestions for a durable gold color fill or possibly a way to seal the fill that doesn't "stand out" and isn't hugely labor/time intensive? Or suggestions on where to go to find help with something like this?

-Glen

[Scott Holmes]

Shellac burn-it-stick and a burn-in-knife. My business cards are laser engraved on paperbacked cherry veneer. I have used the shellac sticks to fill it in on a few cards... burnt orange for Univ of Texas clients and burgandy for Texas A&M clients.

I have done some it white too, just to see how people liked them.

I think the shellac burn-in should hold up better than paint. Burn in sticks are available in many colors and you can mix them on the knife to get about any color you want.

[sheldon pettit]

I would agree with the burn in sticks if they were available in the color gold that you need, but i only know of one or two gold colors of such that i have used from the main suppliers of such?

You don't state how deep or wide or big the engravings are? So that limits my suggestions as of now, sorry. One thing i always used in the past for such work was acrylic and gold bronzing powders that i mixed myself to come up with close matches to other golds. For conservation work i chose the paraloid line of acrylics such as B-72 or 69. Here again, on what your doing, i would not paint it on but "fill" the areas flush with the mixture for best long term results. "lining grade bronzes being the finest, will work best in the acrylic media i'm mentioning.

Another old method was to rub up some 24 K gold leaf in a mortar with a pestle and some gylcerin until turned into a fine powder and then by use of hot water in a fine strainer the glycerin would be removed and the powder then put out to dry and then mixed with the desired medium. This gold will of course never tarnish but it is un-avoidable if you use it as a lining only, to assure that dirt and grime will not eventually cover and dull the look.

The "best" over-all thing to do is to "INLAY" the lettering in a like style in a permanent manner flush with the surface. There are plenty of laser engraving companies that would do that for you, but as to cost i can't say?

Anyway, hope this is helpful.

SAM / Chemmy

[John Coloccia]

I don't really know of any coating or process that holds up to constant handling. It seems that everything either wears through or develops rub marks from handling. The ultimate solution may be to do a laminated part...black over gold...so you engrave through the black into a solid color. That may or may not be possible. I don't know exactly what you're doing.

I might be tempted to take a small brush and seal the color with Behlen's Rock Hard varnish.

[Glen Monaghan]

The engravings are "hair line", about 0.006" wide, and about 0.02" deep. Here's a couple of pictures of some tests I did and have subjected to moderate, less than expected, wear. The scale at the top is centimeters (millimeter rulings). The surfaces being engraved have a somewhat curved shape that varies slightly from piece to piece due to hand construction by craftsmen, and so don't readily lend themselves to inserting inlays without excessive time and effort. A fill process would be ideal.

Best current effort used a gold enamel paint to fill the engraving, squegee'd into the gaps and overfilled to allow for shrinkage, then allowed to dry. Excess paint was subsequently wiped off with solvent so that the remaining fill was flush with the surface, which was then buffed slightly to match the original surface appearance.

The "Glen" in the first picture is showing definite signs of dulling and some wear (loss of material) compared to the "Mon" part. In the second picture, the drawing, the "o" and part of the "m" show both dulling and significant loss of fill resulting in a spotty appearance.

I'm not familiar with the burn-in sticks but, as they say, "google is your friend" so I'll check that out. We previously tried some acrylic paints but they wore faster than this enamel, but I'll have a look at the paraloid acrylics, whatever they are. From Sheldon's description, it sounds similar to a "cold cast" epoxy process which I've looked at, but two manufacturers of specific cold cast epoxies have said they wouldn't be durable enough for this sort of outdoor use.

-Glen

[sheldon pettit]

Glen, now having seen it, my ability to give more sound info is at maximum

seeing how delicate the work is - no - my first reccomendations won't do, sorry, just guessing at the beginning.

Now, unless you get back to me on the tactile qualities of the grip material itself and not loosing any of it, i would recommend inlaying a hard material, even brass itself and etching it much deeper than what your doing now. Then you could fill the brass with black instead of gold for a long time wear and ease of re-doing if and when necessary - much easier to repair black than gold.

[Glen Monaghan]

Sheldon,

the materials in question are micarta and G10, both some sort of resin impregnated composites. I don't think there is any need for inlaying a different material and etching/filling that. It's not the engraving that is wearing, it's the enamel fill. Seems like whatever you'd fill the brass with would either wear similarly, or if it was durable enough, would be usable in the current engraving?

-Glen

[sheldon pettit]

Depending on the thicknesses available then you could just sandwich the micarta/g 10 and make a brass overlaid with micarta and then you could engrave deeper through the micarta to expose the brass, this would be permanent. Just a thought.