Spreading Boards
Spreading Boards
By Jeff Smith
How to make Spreading Boards for spreading the wings of butterflies, moths, and other insects where it is desirable to have at least one side of the wings flattened horizontally. Other kinds of insects may be dragonflies, caddisflies, praying mantids, large planthoppers, grasshoppers, or even some wasps and bees.
Images and text by Jeff Smith – Curator of Lepidoptera – Bohart Museum of Entomology – University of California at Davis.
This shows a finished spreading board. I use standard white pine for cost and availability, and look for boards with widely spaced grain that is soft enough to easily push pins into it. Commercial boards often use basswood, which I find splits when the pin is pushed in. Soft materials like Styrofoam are unacceptable as they are too soft to hold the pin firmly.
Notice that the wood is slightly angled downward toward the center groove. When a specimen is removed from the board there is a tendency for the wings to “droop” slightly, and this allows them to droop only to a horizontal position.
Here we see a “Queen” butterfly as it would look when spread on the board. The wings lay flat on the wood, the body fits properly in the center groove, and the pin goes down into a soft material to hold it in place, leaving the proper length of pin above the insect’s body.
An end-on view of that butterfly showing the pin perpendicular to the board and the wings lying flat.
Step 1
Step #1 is to cut the top wood to width and length. I use ¾ inch white pine and find it to be perfect for this use. The width of the wood depends on the wingspan of the insects you plan to curate. Small moths or butterflies may require only a 1 inch width while large silk moths or hummingbird moths may require a board width of 2.5 inches or more to accommodate their wide wingspan (giving an overall width of the spreading board of 6 to 6.5 inches).
Step 2
The length of each board should be about 11.75 inches. This is by design, as I use standard wax paper over the wings and that paper is exactly 12 inches wide. When cut into strips this will leave a ¼ inch overhang at the bottom of the board that you can easily use to lift the paper when spreading the insect’s wings.
Step 3
In this example my boards are 2 inches wide, and the finished board will then have an overall width of around 4.5 inches, perfect to use for most butterflies and moths.
Step 4
The next step is to make that angled cut on each of the boards. A table saw is perfect for this as you can adjust the blade angle to just a few degrees off perpendicular.
Step 5
Now we run each piece of wood through the sawblade to cut off a fine layer and leave the angle on the wood. Now is also a good time to preach about power tool safety. In addition to EYE PROTECTION it is advisable to use an appropriate “hold down” tool to keep the wood on the table as you make the pass. I can tell you from unfortunate experience that a piece of wood flipping up off the blade can do some serious damage to fingertips.
Step 6
The perfectly-cut pieces of wood that will be the top surfaces of our spreading boards. The inside edges are exactly even in height.
Step 7
Another view of the matching pieces showing the inside edges having the exact height. This is important when spreading the specimen, so that the wings on one side are not forced higher than the wings on the opposite side.
Step 8
Now we cut the bottoms for each spreading board. This is a great time to use up scrap 3/16” plywood you may have lying around, which I create when making insect drawers (see that “How To” lesson on this website as well). The bottom piece will be exactly the width that you want the finished spreading board to have.
Step 9
We next cut each bottom to the exact same length as each of the top pieces. I use a power miter-box saw for this for accuracy and speed. Note on the left of the bottom piece is a block that is part of the template I use for making repetitive cuts-to-length of top pieces and bottoms, since I often make several dozen spreading boards at a time.
Step 10
When making this cut with a power saw (any power saw) please BE AWARE of where your fingers are! Many people have lost fingertips to these tools when distracted or not watching carefully. With this cut the bottoms and the two top pieces are now exactly the same length.
Step 11
Note that on a finished spreading board there is a piece of wood between the tops and the bottom. The height of this piece of wood establishes how far down the pin can go when placing the specimen on the board. I find that a small piece ¾ inch high is perfect, and it’s another way to use up leftover scraps of wood.
Step 12
On each side we find a similar “spacer” of wood that provides support for the wood when you are pressing pins into it during the spreading. This prevents the wood from moving up and down. In this case it too is ¾” high to match the end spacers.
Step 13
So, we cut those pieces of wood to length. The ones for the sides are not critical and can just be short pieces. However, the pieces for each end must be exactly the same length as the width of the finished board, so use the width of your bottom piece as your guide.
Hint: as you see on this board, leave openings on each end of it so you can tip out any pins that might accidentally fall into the groove while you are working.
Step 14
I use a block on the right side to act as a template so that all cuts are exactly the same length.
Step 15
Now we have all the pieces needed for a spreading board – the bottom, the 2 spacers for the ends and 2 for the sides, and the right and left side boards of the top. That white strip you see on the bottom piece is the material that will be glued on the bottom, under the top pieces, so that you can push the pin into it when spreading the insect. More on that in a few more steps.
Step 16
Since I do make so many spreading boards to give away at “demos”, I prefer a nail gun for the next steps. It saves a LOT of time, but a hammer and nails work fine too.
Step 17
To attach the bottom to the spacers I use only ¾” long brads in the nail gun. This way they do not go all the way through the spacers.
Step 18
A bead of wood glue along each end spacer and we then nail the bottom to them, making sure the ¾” dimension is in the vertical position. Nailing is done from below, through the plywood bottom and into the spacer.
Step 19
The view of this step when done.
Step 20
Then a bead of glue on each side spacer and we nail that to the plywood from the bottom.
Step 21
And, the finished view after this step is completed.
Step 22
Now we need to fasten in that soft material in which we will push the pin when spreading. This MUST be done before nailing the top pieces on or you won’t be able to get them into place easily.
Step 23
On top is some pressed paper product with a white surface that is available in 4’ x 8’ sheets at some building supply outlets. I no longer use this, as I no longer can find the soft variety in which insect pins easily could be pushed. So, I have gone to a thick polyethylene material that is readily available and does a great job of holding the pin. This is at the bottom of this image.
Hint: you could also use soft balsawood, but I found that the grain in this wood often misdirected the insect pin as it went in, and the position of the insect’s body was harder to keep where I wanted it.
Step 24
For the polyethylene foam I find hot-melt glue to be perfect for attaching it to the plywood bottom.
Hint: cut these strips wider than the gap you’ll have between the top pieces so that the insect pin does not miss the soft material below.
Step 25
Now we nail on the 2 top pieces of wood, making sure the middle gap is even from top to bottom and the width we want. For this I put a bead of glue on the top of each of the spacers and then use the nail gun to firmly attach the top pieces.
Step 26
Just another view of the completed (almost) spreading board.
Step 27
An end-on view of the board. Note that the surface we cut at the angle is the TOP of the board.
Step 28
I switch to 1” brads (or nails if that is what you are using) and nail down through the top pieces into the spacers below.
Hint: with the nail gun no drilling is needed, but if you use a hammer and nails it pays to drill a hole for the nail, as this will prevent splitting of the wood at the ends.
Step 29
Now, since we want these products of our creation to be PERFECT, sanding the ends to smooth everything evenly is a good step. After all, our craftsmanship is a reflection of our pride in what we make. I use a 12’ disc sander that greatly speeds up this process.
Step 30
The perfect end of the spreading board, more attractive but also with stray slivers of wood removed.
Step 31
Just another view of the sanded end of the board.
Step 32
The final step before actually using the boards is to cut the wax paper that will lay over the tops of the wings of the insect you are working with. I bought some rolls of paper from a supplier that was “meant” for this use and threw it all away, finding it more difficult to work with than plain old wax paper (a buck a box at “dollar” stores).
Hint: standard, inexpensive wax paper is nearly clear, allowing you to see the wings through it while moving them into position.
Step 33
Cut the paper in single strips that will run the length of the board, and cut the strip slightly narrower
than the width of each top piece. When you pin the paper onto the wood leave a narrow gap between the inside edge of the paper and the edge of the wood next to it. The next image will show you why.
Step 34
When using a “probe” to move the insect’s wings into position this space next to the edge of the paper allows you to “grab” the wing, at a strong wing vein, without having to maneuver the tip of the probe under the paper. This is a huge time saver and improves accuracy.
Hint: I use one long strip of paper down the length of the board, rather than small strips placed over individual wings, as you often see depicted in tutorials on “spreading”. In a separate “How To” article on this website we will show the process of spreading the wings of insects in detail.
Step 35
Attach the wax paper at the top of the boards using big-headed pins. The use of pins that are all the same color is not necessary. I’m just anal that way. Have fun spreading!