MOUNTING, PRESSING AND GLUING

A Marquetry Press ..... by Paul Armstrong

Mounting a Marquetry Picture ..... by Carol Teal

Making and Using a Marquetry Press .... by John Sedgwick

 

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A Marquetry Press

by Paul Armstrong

At the last meeting, I butted in as is my habit, on a conversation between John Sedgwick and Janet Trimble. It seems that Janet was having trouble with a marquetry assembly buckling and taking on awful shapes. This is usually due to the fact that different woods absorb or release moisture from the air at different rates, and wood expands or contracts vastly more across the grain than along it.

I once made a 50" round, 2" thick maple butcher block table which became nearly oval every summer - great for those extra guests that drop in unannounced. Marquetry, however, because of the large number of odd grained pieces and types of wood, is particularly prone to buckling and cupping.

Janet's solution was two pieces of plywood with the marquetry between and a heavy weight on top. This didn't work well for a simple reason: A one hundred pound weight might seem like a lot, but if it is spread over a 20 inch square piece of plywood, that amounts to only 4 ounces per square inch - not very much, and wood can have more tension than that. Conversely, a one hundred pound woman wearing spike heels, or Tim Curry, if you're a die-hard Rocky Horror fan, can exert as much as 1600 pounds per square inch on a ¼" square heel dimension.

So where is all this leading? My suggestion, as ever, practical, was to park one's car on the top of the plywood. It was soon pointed out to me that cars have uses other than marquetarian, but I used to drive a Ford van and as vehicles go, it made a better clamp.

My next idea was to actually begin and finish a picture in the same season, thus keeping the atmospheric conditions more uniform. When the laughter died down, John had a better suggestion: Using the same plywood (¾" thick is best), place a pair of hinges along one edge forming an envelope, then use one clamp at the opposite end to pull the assembly together, once your picture has been placed inside. Because there was no allowance made for any thickness between the sheets, the extra veneer thickness adds a good deal of tension on the hinge and with the clamp and leverage working for you, the pressure is ample to keep the veneer flat indefinitely.

For veneers already buckled, not just marquetry pictures, but burls and crotches as well, mist over them with water in a plant sprayer or clean 'Windex' bottle, place them between a few sheets of newspaper (brown kraft paper is better) and place - but do not clamp in the plywood press. Allow a couple of hours for the moisture to penetrate and soften the wood, then apply pressure. A crunching sound means too soon or not enough moisture.

For those of you who may remember the oval mahogany drop leaf table, I brought in last summer, for which John (Sedgwick) did an impressive job of marquetry, there was an oval flower petal design in the centre measuring about 11 by 7 inches. It was flat when I received it, but by the time I got around to using it, it had become a very pretty, exquisitely crafted salad bowl. ( I rarely follow my own advice, and I should have known better). The centre of the flower pattern was a good inch and a half up from the petals. To press this would have been to invite disaster and bring the curs of the Sedgwicks down upon my head, especially with a glue, at 200 degrees F. and 300 psi. The solution was simple, however. Using my spray bottle, I misted only the outside edges of the oval, on both sides, damper on the edge, less damp, to dry in the centre. Miraculously, as the wood gained moisture and expanded, only on the outside, the whole thing flattened out to nearly perfect condition in the space of an hour. Five minutes in the press, and twelve Hail Mary's later, I took it out, and it was virtually perfect, which proves my point that a good craftsperson is one who can hide mistakes better than everyone else.

One final note - Those of you who saw the video on marquetry on PBS, or at the meeting, using a piece of railroad track as sufficient weight to clamp a marquetry assembly in place only works well if the locomotive is included - which brings us back full circle to my original idea.

(Paul is a professional cabinet-maker specializing in custom-made period pieces, replete with inlay/overlay. - Ed.)


Mounting a Marquetry Picture

by Carol Teal

from Canadian Marquetry Feb 1986

The following is the procedure I use to mount all my marquetry pictures and have found it to be a very good one.

  1. Square picture and choose the frame width, stringers, etc. Cut board to the overall dimensions.
  2. Bond back and edges. The formula for the order in which this is done, is "BEST" – Back, Edges (top and Bottom), Sides (done after ends so the end grain on top and bottom edge strips won’t show) and last Top (the picture face).
  3. Lay top or face of picture. Centre picture on board and draw pencil line around it, or measure in from board edge the frame and stringer width and draw lines accordingly. Lay picture on the board to recheck. Make sure you can see all four lines at picture edges.
  4. Apply contact adhesive to picture back and board according to manufacture’s directions, extending the adhesive ¼ to ½ inch beyond the lines on the board.
  5. When adhesive is ready for bonding, cover board with a slip-sheet of waxed paper leaving only top line uncovered. Carefully lay picture, lining it up with all lines and allowing it to adhere to the top line. Gradually remove the slip-sheet and bond picture to the board, smoothing it from the centre outward.
  6. Now put masking tape on the edge of the picture and re-apply glue to the stringer area on the board. The tape keeps excess glue off the picture face. Also apply glue to the stringers.
  7. When the glue is set, put a small piece of waxed paper over the picture and board at each corner where the stringer mitre will be. The waxed paper squares are 1 or 2 inches square. Apply stringers to picture edges, allowing only a small part of the stringer to contact the board at one time. This is done by slightly bending stringers (holding one end up slightly) so they come in contact with the board slowly, or you can use a slip-sheet here as well. Make sure to get stringer tight to the picture as you apply it. Push it tight with blunt handle of craft knife or other tool. When all stringers are down cut mitre with knife where the lines intersect. Now the purpose of the waxed paper becomes clear. You need to remove the cut-off scraps of the stringers. If scraps stick to stringer borders, just carefully remove them with a craft knife blade. Then remove waxed paper pieces and press down stringer corners.

Frame strips are applied in the same fashion as the stringer strips using the waxed paper squares on the corners of the board to prevent premature bonding before mitres are cut.

  1. Cut oversize border or frame strips. Only one side of these must be straight and the outer edge need not be parallel as it will be cut away.
  2. Apply glue to oversize frame strips. Cover stringers (or edge of picture if not using stringers) with masking tape to protect from excess glue and apply glue to board.
  3. Place waxed paper squares to cover corners where strips will overlap.
  4. Slowly apply frame strips to edge of picture (or stringer edge) pushing strips tight to picture edge as you go. Overlap in an under-over manner. You can adjust which side is over which, for cutting handedness.
  5. Now turn picture face down on worktable and trim off excess frame veneers. (edge of frame is now flush with board edge.)
  6. Turn face up, and using a straight edge, cut mitres from inner corner of frame to outer corner of board. Hold knife at a slight angle away from centre of body (right-handed person angles knife handle toward right side slightly.)
  7. Carefully remove excess frame veneer from mitred corners. The waxed paper squares prevent scraps from bonding with the board. Using a flat square-ended knife blade, gently lift corners of frame to remove the cut-off end pieces. They will be stuck to the under side of the frame at some points, but since the contact cement is only on one side of this union, it is not a complete bond and the pieces are easily removed by slipping the knife blade carefully between the veneers.
  8. Once scraps are out, remove waxed paper squares and press corners to the board with a veneer roller. If glue loses its power to contact, just heat the corner with an iron to reactivate it after mitre has been cut. Roll down with veneer roller.

Using this method, the mitres should always be perfect to the board corners.

 


Making and Using a Marquetry Press

by John Sedgwick

Although there are several other options to a “Clamp press” such as a vacuum press and the use of contact adhesive, by far the most used system of gluing a picture is the mechanical press using white PVA glue. In the previous article by Paul Armstrong it is correctly noted that the pressure applied by a heavy weight while appearing considerable, is insignificant when distributed over a wide area.

Procedure

The finished piece of marquetry is assembled as a packet to be inserted into the press as shown in the drawing below. The first thing to know is that as soon as you put water near your marquetry picture it will begin to warp. So the faster you can get it in the press the better. You will need the following

1-A veneer slightly bigger than the board onto which your picture is to be glued.

2-A stable substrate ½” or ¾” thick, bigger than your picture + expected framing borders.

3- Veneer tape

4- White glue, (not yellow carpenters glue!!) a wide glue brush, and preferably a small roller.

5-Several sheets of newsprint cut larger than your picture 

6- A veneer press as shown on the following page.

7- Step-1

Trim Picture and square corners, if there is a chance that after gluing, the flattening of the picture will slightly distort, or move it out of square you may wish to install the border stringers later. In which case make sure the board is large enough. 

Step 2 Square and centre picture on the board, with or without stringer then draw pencil line around it. You can also draw diagonal lines from each corner to check the picture to be square to the board.

 

Step-3 Cut the mounting board –use M.D.F. or similar product, if you use plywood make sure it is of good quality, many hours of work can be ruined by using rough plywood which may have cavities or suspect gluing of the laminates.

Step 4 Cut backing veneer slightly bigger than the board and stick tape fingers on as shown.

Step-5 Place the picture on the board make sure you can see all four lines at picture edges and corners touch the diagonals. Apply masking tape on the board about ¼” beyond the pencil lines.

                        Notes:    This is the last opportunity you will have to check the picture before it is glued down take the time to check the following carefully

 

A- That every piece of the face design is well covered and glued securely with Veneer tape

B- There is no tape of any kind anywhere on the surface to be glued down.

C- There are no overlapping pieces, especially on the stringer borders. This can easily be established by running your hand over the surface.

D- All of your equipment is ready and there will be no delay once you begin to apply glue.

E-Take the phone of the hook or tell anyone present to take a message, you will be busy for the next 5min.

 

Step-6 Apply glue to the complete backside of the substrate

How much glue? A visual rule is that the glue should be thin enough to appear as spilt milk and be spread transparent and even enough to see the substrate below. I use a soft rubber roller used in screen-printing called a “Brayer” to spread the glue, after I roughly apply it with a brush. The roller spreads it perfectly even eliminating any puddles and the need to squeeze out any excess glue trapped beneath the veneer.

Glue failure. Excess glue is the primary reason for failure to press the picture “flat”. From your lessons in Physics you may recall that it is not possible to compress a liquid, which is fortunate fact in some instances, especially when you come to apply the brakes on your car, or operate mobile hydraulic excavation equipment. So a puddle of glue in the centre of the substrate will not completely squeeze out and usually cause a distorted ripple on the veneer surface.

Step -7 Place the substrate with glue side down, in the centre of the backing veneer aligning the grain direction the same as the predominant grain direction of the face design/picture. Never put water-based glue directly on veneer!!

Step -8 Apply glue to the board within the masked area and spread evenly. Remove the masking tape when you have finished spreading glue.

Step -9 Wet the veneer tape fingers with a moistened paper towel

Step -10 Place picture on the substrate within the registration area and align with the diagonal lines as close as possible and fold the moistened tape fingers over the face veneer an press firmly.

 

 

 

 

 

 

 

 

 

 

 

Step -11 Putting the packet into the press can be a four handed job so the press should have already been set up by holding the Cauls open with four spacers

Step -12 Place “package” in the press on 3 layers of newsprint in the sequence shown below

Step -13 Place 3 more layers of newsprint on top of package, remove spacers and tighten nuts on the threaded rod by hand until all the nuts are finger tight

Step 14 Tighten the nuts with a wrench in a rotational sequence until the chamfered ends of the stretchers are flat on the cauls top and bottom. Remove in 1hour and check if everything is OK place it back in the press for 24hours.

Step 15 Trim the backing veneer to size of the substrate. Do not trim the board to suit the picture until you have removed the tape.

Step 16 Use a hand scraper to remove as much tape as possible. This will also establish where the low spots are due to differences in veneer thickness. Moisten any remaining tape with water or a cotton rag. 

Notice I said “Moisten” excess water would reactivate the white glue. After about a minute of contact with water the tape will loosen and can be peeled away. Repeat as necessary to clear the surface of all tape.

Step 17 Trim substrate to match the picture dimension. Veneer or glue solid frame onto the edges of the substrate. Continue to level the picture face by scraping and final sanding ready for finishing.

 

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