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Cherry – CNC Maker Zone

Choosing a wood finish to enhance colour and grain

After all the love and care we put into our CNC projects their success often hinges on how well we finish the exposed wood surfaces. Sometimes we may just want to leave them plain, even unsanded, but usually we’ll be wanting to bring out the colour and grain structure to show off the beauty of the wood we’ve chosen. So what is the best way to do that? Should we just cheat and use clear-coat, or should we use traditional techniques like Danish Oil or Shellac sanding sealer? How much work is involved varies a lot depending on which we choose, so is the best way the one that involves the most perspiration, or can simple ways provide more inspiration?

To try to answer some of those questions I decided to do some tests with six of my favourite woods: Basswood, Oak, Cherry, Walnut, Mahogany and Birch plywood, as shown in the photo below. I then decided on four finishes: plain unsanded wood (A), Plasti-Kote aerosol clear-coat (B), Danish Oil (C) and Shellac sanding sealer (D). The last three were all done in two coats and after light sanding with 400 and 1000 grit sanding paper/pads. I think one of the most interesting things the photo shows is that all three surface finishes, even the simple spray-on clear-coat, enhanced colour and grain significantly.

Comparison images of the six woods before and after applying surface finishes

The unsanded woods (A) were obviously a little plain and dull, but still nice for many uses. The simple clear-coat (B), however, was much more interesting as it’s a very simple finishing process yet brought out the colour and grain structure very well. The main comment in comparison to the other finishes is that it gave a slightly darker look to the wood, although not in an unpleasant way. In comparison, I think the Danish Oil (C) gave a slightly nicer look to the grain, as well as bringing out the colour of the wood beautifully. Probably that’s due to it being mostly oil (see my post here) and so likely soaked deeper into the wood surface before hardening.

The sanding sealer (D) also gave a nice finish, although it was slightly duller. That’s not surprising though as its’ purpose is mostly to provide a sealed surface that can be lightly sanded smooth before applying other coatings. In the past I’ve used it with a finish of wax polish for a traditional look, and I think that would work well with the results here. The only other thing to note is, for me anyway, that the finishes improved the plain colours and grains of the Basswood and Birch plywood, even giving them some of the look of pine which could be useful for many projects. However, for a more exciting look they may benefit from a little wood stain/dye: in the case of the Danish Oil that can include darker oils that are commonly available.

Overall, I think the main conclusion from my tests is that simply applying a synthetic clear-coat to a carefully sanded wood surface is just as effective as more traditional techniques. Certainly it enhanced the colour and grain of all of the woods as well as giving an extra level of darkness if that’s what you want. Of course, using the other, more traditional, techniques gives subtly different effects so they still have a role to play and can be used with a final clear-coat too for some nice effects. Really it’s all down to our judgement, but without any need to feel guilty that using a cheap and simple clear-coat is cheating: in fact it’s a useful technique that compliments traditional finishes very nicely.

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Cutting 1.5mm Cherry wood with a 5W diode-LASER

Cherry is one of those woods we all recognise, mostly by the distinctive colour and beautiful grain. We’re likely to find many uses for it in CNC projects, so I decided I wanted to try cutting some 1.5 mm Cherry sheet with my 5W diode-LASER to see how easy it would be. As you can see from the photo above, the Cherry sheet (with a water content around 9%) was actually quite easy to cut through with a LASER, on a par with similar tests I’ve done with Basswood, Walnut and Oak. The photo below shows the back of the cuts and it’s obvious that too much power, either from a high LASER-power or multiple passes, leads to considerable charring. However, for my use one pass at 75% power, and a feed rate of 100 mm/min, seem to give quite acceptable LASER-cutting results.

The back of the cherry sheet after laser cutting

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