Ancient veneering techniques and glues are a perfect match for laser cutting!

Veneering might conjure up notions of cheap ‘cardboard’ furniture, but it’s been used for thousands of years to create the many of the finest wooden pieces that litter museums around the globe, and this tradition makes an easy transition to the modern era of laser cutting. Plus, it’s easy, if you know the tricks! So I thought I’d share what I’ve gathered on the topic so far. :slight_smile:

Examples:


Simply veneering a sheet of fancy wood to a piece of laser ply before cutting it can elevate what would otherwise be a rather simple design.

Laser cutters make marquetry so easy that it almost feels like cheating… This was literally my first attempt.

Basic Veneering Process & Glue

In many modern woodworking tutorials veneering is done with a PVA-type glue (e.g. Titebond) this isn’t a great option for veneering in general because it requires you to clamp the whole surface evenly and firmly until the glue is dry (which is no small feat!), and it’s even less suited to laser cutting as PVA resists cutting, produces a lot of soot and discolours with heat. PVA also resists surface finishes (varnish, oil, etc), which is especially important when doing marquetry which has a lot of seams.

Normal plywood is glued up with formaldehydes, which you do NOT want to burn in a laser, for your safety, and because it makes for really charred burns.

Laser plywood is usually made using melamine glue, which is hard to find as a consumer. While it does burn cleanly, it still requires the clamping that PVA does.

HOWEVER there is a marvelous glue that is perfect for veneering and has been used for centuries: animal glue (the real stuff, sold as granules, not in a bottle). While not vegan, it’s renewable and readily available at fine art stores (rabbit skin glue) or leatherworking suppliers (hide glue). It doesn’t require clamping when used in a process called hammer veneering, which relies first on water tension to hold the pieces together, then as the glue dries it tightens up and pulls the veneer extremely firmly onto the substrate material (strong enough that if you leave a layer of this glue on a piece of glass, it will chip the glass as it dries, people make pretty signs this way through a process called glue chipping). There’s a good tutorial here demonstrating how simple hammer veneering is.

While it may seem like it’s extra effort to warm a glue, the savings in time/energy/frustration far far outweigh the inconvenience. Not only is there no need for clamping, the glue burns clean and safe with a laser, and you can apply any finish you wish over it, oil, water, epoxy, it won’t show! Plus it’s reversible and forgiving; if you make a mistake or decide you don’t like something, wet it, heat it and remove it. It responds accordingly to humidity changes, swelling and shrinking with the wood, and thus won’t crack with time. It can be used as a grain-filler on textured woods, and you have immense control over the tack and thickness of the glue (by varying the ratio of water to granules) and the gel time (by adjusting the temperature).

If you have a 3D printer, you can use the bed to melt the glue (at 60C) and keep it warm (at 50C) without needing a double boiler, this completely eliminates the risk of ‘cooking’ it (denaturing it due to high temperature).

The powdered glue keeps indefinitely and glue you have made up with water can be repeatedly frozen and melted for future use.

Laser tips

Cutting veneer is rather like cutting cardstock, even diodes can do it. This was cut with a diode:

One of the main struggles is keeping veneer flat in the laser. If you are using a diode laser you can place the veneer under a sheet of glass to hold it flat (use something that isn’t precious as it may etch the glass). CO2 lasers will readily etch glass, so for them you can tape the veneer to something the laser can’t cut (a ceramic tile, a sheet of dull metal, etc). I like to use masking tape/paper painters tape/washi tape to tape mine as I’m not sure if normal sticky tape is made of vinyl, and while the goal isn’t to cut the tape, accidents happen. Plus regular sticky tape doesn’t always remove cleanly and can stain wood.

If your veneer has a lot of curl to it, it may still spring up as it’s cut. This can be eliminated by storing the veneer under weight or (if you have odd-sized pieces) stack them atop something flat (here a chopping board) with largest pieces on the bottom, and smallest on the top. Place them inside a vacuum-sealed bag, and pull the air out. This will keep them flat and also remove the risk of mold.

If they are very very curled, and simply storing them this way isn’t working, you can steam the pieces over a pot of boiling water then let them dry between some blotting paper, under weight (a bunch of books is good!). Let it dry completely before bagging it up, lest you encourage mold.

Marquetry
For the leafy box above, I cut each of the 4 colours exactly the same, which allowed me to make 4 copies, each in different color combinations. Putting them together was a bit of a jigsaw puzzle! I assembled them on some clear vinyl transfer tape that was taped (sticky-side up) over an inverted printed version of that image, then glued my plywood substrate, and brought it to meet the veneers.

This assembly was a bit of fiddling, which I personally rather enjoy, but I am exploring some other methods that waste material but make assembly a lot easier, these rely on temporarily securing the work to a material that won’t be engraved by the laser, and then engraving away the areas of that color of veneer that you don’t want to keep, then assembling these pieces together. I will report back when I have perfected a process for this!

I didn’t make any adjustments for the Karn of the laser, the beam thickness was enough wiggle room to allow the pieces to be placed.

When I do inlay I do like to offset the design by the thickness of the beam’s kerf (in the layer settings) this method relies on the objects being enclosed shapes.

Things I’m still experimenting with:
I haven’t spent much time changing the angle of pieces according to grain line, but it’s traditional to do so and leads to some stunning effects. I’ll experiment with this in a box I’m making.

Sand shading traditionally brings dimension to marquetry. I have been dabbling with a laser-based system for achieving this. My next plan is to sand the work back to its final grit, but before applying the liquid finish, using LightBurn’s Print and Cut feature to engrave shading into the piece.

I’ve assembled these thoughts from various bits of info I have gleaned from around the internet/workshops/personal experiments, one day, if folk are interested, I’ll assemble these into a more coherent guide, but I found info on these topics hard to come by, so I figured I’d present them here for now, in case they’re handy for others. :slight_smile:

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Thanks for posting the info. I’ve only done a couple of projects which used veneer in a very small way but I’m very pleased with the results. I initially used PVA but then sourced some ‘hot-melt’ glue sheets from Ebay which worked well. I’ll keep in mind the animal glue (IIRC from my woodworking classes in school we knew it as scotch glue).

Very nice and useful post - many thanks! :+1: :+1: :+1:

A tip about “animal” glues… If you want to try it out, but don’t want to buy a large quantity of commercial hide glue, you can simply use gelatin… that’s right, the stuff they make Jello out of. Hide glue is simply a form of unrefined gelatin, and using food-grade gelatin in its place will work just fine (arguably, it may be a little better than regular hide glue). You use it exactly as you would the hide glue.

It’s an inexpensive way to try out hide glues, and is an excellent alternative if your hide glue supply is low.

Another tip about using hide glue… These glues need to be applied warm, and typically one uses some sort of temperature-controlled heating unit to maintain it at the desired temperature during use. An inexpensive baby-bottle warmer along with a small jar that fits in the warmer is an excellent way to keep that hide glue warm and ready for use. Here is an example, available on Amazon, but they are even less expensive at a garage sale.

https://www.amazon.com/Breastmilk-Sterilizer-Sanitize-Pacifiers-Controller/dp/B07V9Z8RN8/ref=sr_1_25?crid=265DVXA9LSUZZ&keywords=bottle+warmer&qid=1680634637&sprefix=bottle+warmer%2Caps%2C156&sr=8-25

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Very informative and useful information. The reason I purchased my laser was for marquetry but I have had some issues with kerf allowance being variable enough to produce poor fit on larger assemblies. I’ll be watching for your updates.

Oh! Do you know about the kerf offset in the layer settings window?

It will automatically offset all your enclosed shapes, to make up for the distance of your kerf.

You will need to run a couple of tests to find the right value/thickness of your kerf.

I like using a 10x10 grid of spaced 5mm squares (needs to be spaced to allow for the offset).

Once cut you can glue/tape them together and measure them to see if they are the correct size (should be 50mm (10x5)). If they aren’t the right size, you can adjust the kerf offset accordingly. Remember you have to divide the difference between your result and 50mm by 10, e.g if it measures 51mm, you need to change your kerf offset by -0.1mm, to bring it back down to 50mm.

You could just do it with one piece, rather than the grid, but when working with such thin/flexible things and as part of an overall process, it’s better to run a bunch of shapes, I reckon.

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Yes I did use the kerf offset and had completed the kerf measurement process. What I found was a variation in kerf depending on the species of wood. This also had a considerble effect on the speed and power required. This can be seen in the photo attached. The white rings did not fit well although the center petals did. I will continue to experiment.



My experience with laser inlays and marquetry is that the fit of one piece inside another can be different with different woods because of how they burn. I don’t use kerf offsets because of this, tend to be too global for all the parts of a file. I use offset shapes and set differing offsets after experimenting for a good fit.

The reddish pedauk pieces in this design are good examples- the pedauk wood had a wide char margin around it- those pieces needed a greater offset to fill in the lighter wood.

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I have also reached that conclusion.

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Oily woods like padauk will burn more (need more offset) versus non-resinous woods. I’ve fond that by going to less heat and doing two versus one pass can help even out the wood species kerf difference.
Also, with pieces that have straight edges, I’ve found it beneficial to cut slightly oversize then the piece can have it’s edge dragged over a strip of sand paper to achieve an excellent fit. If anything, the light edge sanding removes charring which will show as a black border around the pieces.

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Instead of offsetting the file you could also save different settings to your library for each wood (with different offsets). That way if you want to cut the design in a different colour way, the original is preserved.

I would agree, except that even in the same shipment of veneer, the burn margin can be different. I work on one wood and its inserts at a time, testing to see how much I need to offset outside. .003" to .006" is the range of offset to the outside is my usual range.

Interesting! Is your veneer perfectly flat?

1.5mm thick veneer, and mostly flat. However, I use weights to hold it down flat when I cut the pieces.

Interesting! I’ll keep playing with it and see if I can come up with any tips to help. Wood is a tricky material though, with all it’s natural variations.

I also personally feel meeting it’s not worth offsetting at all; marquetry was often done by stacking all the colours and cutting them all together with a fret saw, (video here) meaning there was a kerf of the width of the scroll saw all around each piece, and this was disguised/emphasised by rubbing in charcoal dust.

I personally quite like this approach, both for it being a bit easier, but also I think it looks better, highlighting the difference in materials.

This is definitely a personal opinion though and I understand it must get frustrating having unpredictable results!

Dark lines around an insert or not is surely a personal preference. I chose Titebond II premium glue to get a clear/lighter glue margin where ever the gap exists.

For those that would like to use the Kerf Offset to help their parts fit better, I have created a tool and posted it here: