If your desk is a valuable antique and/or is of historical
interest, then replacing the leather insert is best left to an expert unless you
have confidence in your do-it-yourself ability. For desks that do not fall into
that category then there's nothing to stop you, because it's a perfectly simple
procedure.
Should the insert being replaced have some ornamentation around
the edges, either as blind tooling or with gold leaf embossing, and which you
want to reproduce on the new one, then there is a bit more to be considered.
Blind tooling:- That just means impressions are made in the leather by means of heated tools, pallets, rolls,
fillets or combinations of one or more of these. As the name implies, blind tooling does not entail the use of leaf
metal, foil, or any other colouring material, with the possible exception of something like Tandy's Hi-Liter
Finish,
which can be used to darken the impressions.
Gold tooling:- In the traditional method of gold tooling the design is blinded
in, firstly through paper, and then again directly on the leather. The second working of the tool polishes the base of
the impression and assists in creating a particular brilliance in the tooling. An adhesive (glair) is applied to the
leather, directly into the blind impressions, and strips of gold leaf are laid over them and held in place temporarily
with a thin film of vaseline, or the gold is in roll form. It is then pressed permanently into place with a heated tool.
See here.
Something worth bearing in mind are the differences in costs. Metallic foil is available in roll widths of 1" - 24" and
lengths of 400' in shades of gold and silver, costing roughly, for the 1" wide £2.00, to £12.00 for the 6"wide.
Genuine gold foil is also available in widths 1" - 24" and roll length 200' but costs are somewhat greater at
£76.00 for a 1" roll and £230.00 for a 3" wide roll.
Ready to fit inserts are available from lots of suppliers,
but they will not be inexpensive. Send them the precise measurements
and details of any ornamentation, and state the type of leather required. As a
rule of thumb you would expect vegetable-tanned tooling leather for larger desks
and skiver for smaller ones. So, for example, a ready-to-fit vegetable-tanned leather insert,
say 3' x 2', with some modest gold-leaf tooling, will cost approximately £150.00,
or £650.00 for size 6' x 4'. Skiver costs less, for one thing it's a thinner
leather, usually sheepskin, and for anything other than a small desk more than
one piece will be needed as a skin averages 6²' - 8²', thus a 2' x 1½' piece will cost about £45.00 and 4' x 2' no more
than £110.00 at present prices.
Vegetable-tanned tooling shoulder is my leather of choice and
buying it yourself should cost, more or less, £5.00 a square foot. Un-trimmed
double shoulders of 1.2 -1.4mm weight are approximately 16²' - 18²' so half a shoulder,
for example, should be all you need to cut out a 3' x 2' insert. Add the cost of the dye,
metallic foil gold leaf, and tools for the ornamentation if you want to add some, and you'll
still have change in your pocket.
To remove the old leather insert soak it with some warm water to
loosen the adhesive. When pulling it off it doesn't matter if it gets torn,
you're throwing it away. Just ensure you keep a bit to remind you what the
original ornamentation was like if it's your intention to reproduce it on the
new leather.
Before cutting out your leather you need to measure
the recess for the leather. If it is a square or rectangle, check the squareness
by measuring across the diagonals. If you have any doubts, or the shape is not
regular (often the case in older pieces), make a paper template carefully
marking which is the face side (tape down the paper you are using to trace the
recess so that it doesn't move. With a carpenter's pencil use the broad side to
mark round the edge of the recess). This template should be accurately cut to
size and checked for fit in the recess, as you will mark out exactly around the
outer edge for size. Leave some spare material all round for final fitting and
trimming.
To reproduce ornamentation round the edges use a simple hand embossing
wheel carriage and any of the many interchangeable wheels that are available.
They are excellent for borders, tooling, and so on as they can be heated and the
design burned into the leather. The carriage is equipped with a thumb screw so that the embossing wheels can be easily
changed.
Use the proper heat range to do the job. If the iron is too cold, the leaf will not transfer evenly. If it
is too hot, the gold will break down and at times the iron will skit. The iron being too hot causes the most problems.
Very little pressure is required to perform the actual transfer. Narrow lines require less heat.
Wider lines more heat. Circular patterns may be accomplished by using the outside guide or an extension to the outside guide if more "reach" is
required. Always use a mounted sample piece of leather to test before running each row of a particular style, to allow
for variations in room temperature, humidity and leather properties.
When the correct heat and speed are used in conjunction with a modicum of skill, perfect repeatable results can be obtained.
It is necessary to apply a protective coat of sealer to prevent tarnishing and
oxidation of metallic gold leaf.
hand embossing-wheel carriage
interchangeable wheels
With the leather cut to size it's time to stick it into place. Wallpaper paste is a satisfactory adhesive, being
water-based it is easy to clean off any place it shouldn't be. You can of course use an original 18th century glue,
wheat paste! (Source of wheat paste:
Zen-Instant-Wheat-Paste). Apply with a plastic spreader that has a serrated edge and spread it on as evenly as
possible. Bear in mind that the thickness of the paste will determine the drying time, as will the environment, as
the leather expands and contracts accordingly, also a period of time is required for shifting the leather about to
get it fitting perfectly (as you will not get it right first time) with the edge ornamentation, if any, parallel to
the edge of the desk.
If the desktop is a large one then mark the centre of the leather and the middle
of the desk, roll up the leather from each end to meet in the middle, line up
your marks and unroll the leather. Use one of those small paint rollers, the
sort for getting behind radiators, to smooth out any air-bubbles from the centre
towards the ends, that will at the same time squeeze out any excess paste round
the edges so that it can be wiped off. After getting it smooth you may need to
do a bit of compressing and stretching to get a perfect fit. For every square
foot of leather it can be stretched or compressed (on the average)
¼". Any excess will need trimming off from the edges before the adhesive
has set, by doing so you can still manipulate the leather to close up any gap
should you inadvertently trim off too much. Protect the
wood by using a thin strip of plastic or similar to act as a buffer
between it and the leather, then use a steel rule as your straight edge, and
start trimming. Better also to make several light passes with your sharp blade
than one heavy one otherwise you may move the insert. Ensure any edge embossing doesn't get out of synch but
stays straight.
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