Saturday, November 7, 2015

Assembly board used in the French method

The following is a description of how to use the assembly board and how to make one. Patrick Edwards and Patrice Lejeune have some really great videos involving the assembly board on Youtube HERE and HERE.  Also, I cannot stress enough the value in going and learning directly from Patrick and Patrice in San Diego.

I learned to cut marquetry on the chevalet de marqueterie (the chevalet, for short) using either the Boulle method (packet cutting) or the piece by piece method.  I was quite fortunate to learn this from Patrick Edwards and Patrice Lejeune at American School of French Marquetry
After cutting out all the marquetry pieces in either of these methods, you end up with a bunch of pieces that need to be assembled into the final picture; sometimes, it’s a pretty intense jigsaw puzzle.  See Figure 1; this is a fairly simple one.  
Figure 1

The method of assembling the marquetry picture that the French developed centuries ago involves building the picture face down on paper stretched tight over a board.  The French call it cale tendue.  For simplicity in the English language, we’ll use the name “assembly board” as Patrick Edwards adopted.
An assembly board is simply paper stretched tight over a board, much like an artist’s canvas.  I’ll explain how this is done later in the article.  Hot hide glue is spread on the paper (Figure 2), and the pieces of the picture are placed face down in the glue.  
Figure 2

At this point, the face of each piece is on a single plane with the paper.  At this stage, I press the picture for a couple hours to make sure everything bonds well and stays flat.  Once the glue dries, the back of the veneer is facing up (Figure 3).  
Figure 3

The back of the picture can be sanded to even out any thickness discrepancies.  Mastic (glue and sawdust; I use hot hide glue) can then be applied to the back of the picture to fill any gaps (Figure 4).  
Figure 4

After the mastic hardens, the back of the picture can be sanded again to get rid of high spots.  And if hide glue is being used for the mastic and for mounting to the final substrate, doing a perfect clean up job is not necessary.  Hide glue will bind to hide glue.  Just one of the many wonderful aspects of hide glue. 
The final picture is cut away from the assembly board and is ready to mount, store or send to someone else for use (Figure 5).  
Figure 5

If you’re going to store it for any length of time, I recommend sandwiching it between a couple of boards to prevent warping.  To mount the picture, glue it to the substrate with the kraft paper facing up; the face under the kraft paper is the show face.  Once the glue dries, the kraft paper is wetted with cold water; the paper absorbs the water and is easily scraped away.  The hide glue underneath is also scraped away (the same cold water softens the hide glue on the face) and the final surface of the picture shows through.  Since the back of the marquetry was flattened and the front of the marquetry was already in the same plane and flat, there is precious little that needs to be done once the picture is mounted. 
One advantage of this method is that the face surface is flat.  The alternative is layers and layers of tape, which results in high spots on the face.  When the picture is pressed onto the substrate, these high spots must be compensated for or bubbles are likely in the final piece.  Another advantage of the assembly board is that it is easy to flatten the back and apply mastic. 
To make an assembly board, you need a few things: a board larger than your picture, hot hide glue, European kraft paper, water, and some veneer tape. 
I suspect that the veneer tape is not entirely necessary, but it’s how I learned and is probably cheap insurance. 
I’ve never tried making an assembly board with anything other than hot hide glue, but I suspect it wouldn’t work as well.  The advantage of the hot hide glue is that it gets a fast tack and grabs before the paper begins to dry (you’ll see this in a minute).  I’m not sure other glues would work, but maybe that’s an experiment worth performing.
I have tried using paper other than the European kraft paper.  It just doesn’t work.  The European kraft paper is shiny on one side and dull on the other.  The shiny side is somewhat moisture resistant.  This is critical in making the assembly board, since we are going to wet the shiny side.  This is also the side that the marquetry will be glued to in the end. 
To start with, cut some kraft paper so it is more than twice as big as the board (Figure 6). The kraft paper is going to wrap around the board like wrapping a present.  Cut it big; you will trim it and throw away the waste.  
Figure 6

Lay the kraft paper shiny side up.  Now wet the shiny side with a sponge (Figure 7).  It should be pretty wet.  
Figure 7

Turn the paper over so the shiny, wet side is down and the dry, dull side is up.  Keep the dull side dry.  Now wait.  Waiting is the hard part.  While you are waiting, the paper is absorbing a bit of the water and expanding.  When the paper starts to wrinkle, spread out the wrinkles and move on to the next step.  Grab your board with one hand, hold it over the glue pot, and spread hot hide glue on 3 edges (Figures 8, 9, and 10).  
Figure 8

Figure 9

Figure 10

The edge you are holding will be the hinge side of the paper and will get glued later.  Put the board flat on the paper and fold up the paper tight over the 3 glued edges (Figures 11 and 12).  
Figure 11

Figure 12

Take a razor blade and slice off the paper about halfway down the thickness of the board (Figure 13).  
Figure 13

Now spread glue on the hinge edge of the board (Figure 14 – you may notice that in the pictures I put glue on this edge prior to slicing off as shown in Figure 13 – woops! But it worked out.).  
Figure 14

Grab the far side of the paper, pull it up tight on the hinge side, and fold it over to the far side (Figure 15).  
Figure 15

Stick the paper to the other 3 edges (Figures 16 and 17).  
Figure 16

Figure 17

Since you sliced away the paper from the first fold about halfway down the thickness of the board, you have some exposed glue to adhere to.  Again, slice away the excess paper (about halfway down the thickness of the board) and discard the excess (Figures 18 and 19).  
Figure 18

Figure 19

Put veneer tape over the 3 edges that were trimmed (this is cheap insurance to make sure the edges don’t lift off for some reason…Figure 20).  Now put the board in a nice spot to dry. 
Figure 20

The glue will grab the paper on all 4 edges.  As the paper dries, it will contract and pull tight across the surface of the board.  Since it is only glued at the edges of the board, once your marquetry is glued to the paper, it can easily be sliced away as described earlier.   

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