Monday, April 11, 2011

Wedding Cake Topper Part 4

OK- we are back with part of 4 of the wedding cake topper. So far we have been concentrating on the techniques involved in sanding,  painting, and finishing using an ages old finish called tung oil which naturally hardens to a stain sheen. The difference between this finish and chemical finishes is the time it requires. Tung oil requires multiple coats to achieve the same satin finish that a chemical finisher can provide in one coat. The benefits are that you... well don't have chemicals spraying everywhere. Working with the medium is very natural. There is virtually no odor- and the smell that it does have is very organic smelling- like tangy oil. You also won't end up with a bunch of long lasting volatile organic compounds, or VOC's that continue to stream out in micro-level like you would have with a chemical finish. It's great for people sensitive to what they use on, near and around them. There is a very slight  chance that chewing on it or working with it wet could trigger an allergic reaction in someone with a nut allergy as it is derived from a tree nut but I don't expect anyone to chew on a cake topper. To be extra sure- we are going to do a non-toxic acrylic based clear coat that is toy-safe.

Over the weekend I scrubbed down the wooden pieces again and applied the last coat of tung oil. I let it have a full 36 hours to dry and harden before starting the engraving process which we will get to in a minute. First I had to get the digital files ready. We have already been through a paper cut process. Sometimes by customers are remote from my location and would be unable to have me stop by to show scale and sizing. For remote customers on items that just must be right the first time, I prep and send a paper cut of the product to be used for a hands-on feel of the size, shape, and scale so we can make sure it's appropriate for their application. It allows me to make more precise tweaks and fixes. One of the tweaks was to render some areas to be wood with others painted. The best way to do this in a laser engraving process is to burn off the coats of paint and finish so that you have a precise and defined boundary. (Unless you like that paint by number look then you can try it by hand.) The engraver sees black as where to apply the most power. Files in color are seen by the engraver as needing varying levels of power according to depth of shade. Photo engraving is best done from a color photo and silhouettes in black and white as we want that crisp definition.

Our wedding cake topper will come together in three layers. The middle layer is the only one with engraving definition and features a silhouette of a bride and . The other two layers are comprised of only vector cuts so shading and color are unimportant in the digital file. For vector cuts, the engraver is only concerned with line width as only one line-width will instruct a cut line. Due to the paper proof process, the digital files were really very nearly complete. We did want to add some definition tot he silhouettes and make the flesh colored areas wood colored (heads, bare arms, etc.). To do this we are going to process the file in two stages- an engraving stage and a cutting stage.

The engraving file was due to run last night but we had this wild Texas-style spring storm pop up with 90 mile an hour winds. Surprisingly we didn't lose power (or our roof) and I decided it was not good weather to be running high power electronics. I stayed awake listening for the tornado siren down the street but with winds and rain like that- I wasn't sure you could hear anything but that sound like a frieght train when the tornado is already a-comin'. I digress...

So here's a picture of the beautiful bride...
Bride for Wedding Cake Topper
This is an approximate look of the paper cut. The neckline is an engraved line as are the lines of the inside of the arm touching the dress. I included them so we could get an idea of where the skin would be showing. The first run will remove the light cream paint from the head and arms. Now she looks a little blobby.
This extends the engraving  past the cut line to make sure we don't end up with a smidgen of errant paint. The second run will be just the cut lines and will put back the defintion of the face and hair.

In order to make sure we have the settings right, we will be initially running the Sima Design logo on a corner of the wood to test for removal of the paint and depth of engraving.

I'll run these files tonight or early tomorrow morning so tune in to Part 5 for photos of the test engraving and the full file engraving run of our happy couple.

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