Bath Brick and Gold Cushions

One of my bookbinding heroes, William Mathews, told Enid Batham about his future books in response to the price of gold going up, “I’m not going to wipe off any gold, they’re all going to be smothered in gold”.  Gold finishing has long been associated with the finest bookbinding.  But covering things with thinly beaten gold has been around for a very long time, long before the codex and is associated with power, wealth and the finest in life.  Just think of King Tut’s golden mask, opulent palaces around the world, and the world’s religious icons.

Books decorated in the traditional manner using gold tooling are no longer the height of fashion in book decoration and there are many reasons for this.  I’m not an art historian so will not attempt to analyse why fashions change, but I know one reason gold tooling is not as common as it used to be, and that’s because it’s bloody hard to do to a high standard!  The famous finishers of the past went through a rigorous apprenticeship system from a young age, perfecting skills over decades through constant and repetitive practice.  When stated like that it has some similarities to being a professional musician.  But today there are few opportunities to financially support professional gold finishers, and thus there are now very few people working to this high standard.

But just because one can’t play music to the same standard as a professional, we can all still play a musical instrument and enjoy it, or at least try.  The same is true for gold tooling.  I never expect to do a full run up English spine successfully, but I can put a few lines across the spine and an ornament in the centre of some of the panels, and only a bookbinder will notice how crooked they are!

Loose gold leaf comes in books and currently the most common specifications are 25 sheets per book each leaf of gold being 80mm to 85mm square.  The gold leaf is interleaved with rouged tissue which the gold does not stick to.  The traditional way of handling gold leaf is to move a leaf from the book onto a gold cushion, potentially using a gilder’s knife, cut the gold into appropriately sized pieces which are then transferred to the book being finished using something like a cotton pad with a trace amount of grease on it, or gilders tips for edge gilding.

Most professional bookbinders recommend 23.5K gold because pure 24K gold does not work well. Many also recommend the use of double gold. Double gold is not double the thickness, it is slightly thicker. My supplier specifies there is 14 – 15 grams of gold per 1000 leaves of standard gold leaf, while 15 – 16 grams of gold for double leaf. My supplier does not make 23.5K gold, so I use the closest thing, 23K. The slight addition of another metal to alloy the gold has an impact on colour. Your supplier may carry different alloys, such as copper or silver, which result in warmer or cooler coloured gold leaf.

A gold cushion is simply a wood board covered in rough leather (leather flesh side out) with some padding between the board and the leather.  Many of the classic books on bookbinding provide instruction on how to make a gold cushion, and I have just completed a video about this subject which can be viewed on the DAS Bookbinding YouTube channel. 

DAS Bookbinding YouTube channel – Making a Gold Cushion

In old bookbinding catalogues fancy gold cushions often sit on top of boxes that have draws or the top flips up for storing gilding supplies with the cushion.  While these sound like a great idea, I wonder how practical they were in reality.

As already mentioned, a very small amount of grease will make gold leaf stick to something.  This property is used to pick the gold up off the gold cushion and to get the gold to stick on the book being finished.  But you really don’t want any grease on your gilder’s knife or the gold cushion.  The traditional method of removing grease from a gold cushion and knife is by scraping or sprinkling some bath brick onto the cushion, scraping the powder back and forth with the knife to make it absorb any grease present, and then beat the powder off the cushion.  But good luck finding a bath brick now!  Today most people use powdered pumice or talc as a substitute.

But what is a bath brick and is talc or pumice good substitutes?

Bath bricks were a mildly abrasive household cleaning product about the size of a house brick.  I presume the name comes from the association with householding cleaning and the bathroom, rather than the town of Bath, but there are different stories about this.  Bath bricks were manufactured in the town of Bridgwater, England, which was home to brick and tile factories on the rive Parrett.  The silt from the brick factories’ rubble was formed into bath bricks containing alumina and silica (which is essentially clay – aluminium phyllosilicates minerals) but fired at a lower temperature than house bricks.  There is a website with a fascinating history of bath bricks and Bridgwater.

History of Bath Bricks and Bridgwater

Pumice seems to be the most often recommended substitute for bath brick.  Pumice is a volcanic rock formed in violent volcanic eruptions.  My nontechnical description is frothy lava.  Despite being rock, the rock is so full of small bubbles it is light in weight and easily floats.  Coastal volcanic eruptions can result in vast rafts of pumice at sea.  The composition of pumice is complex.  Pumice is usually a felsic igneous rock, which means it is rick in “elements that form feldspar and quartz”, which means elements such as silicon, oxygen, aluminium, sodium, and potassium.  The name felsic comes from combining the words feldspar and silica.  The commercially available powdered pumices are ground low density pumice with a high silica content.  Thus, powdered pumice is similar in composition to bath brick, and thus not surprisingly a good substitute.

Talc is another silicate mineral which has the distinction of defining the value of 1 on the Mohs mineral hardness scale, where 1 is the softest mineral.  Talc has been used as an alternative to hair washing as it removes excess oils from lack of bathing.  Thus, it is well suited to removing grease and oils from a gold cushion.  The only downside to using talc, and this may not be important, is that the extreme softness makes it a useless abrasive.  New gold cushions can be excessively nappy, and the abrasive effect of pumice can be used to reduce the nap.  Some people also use the cleaning of the gold cushion as a way of sharpening the gilder’s knife, and talc would not aid in this.  Talc is often put on the edges of book to stop leaves sticking together when edge colouring or gilding.

While bath brick has been for a long time the standard substance used for degreasing gold cushions, in the absence of bath brick, both talc and pumice are suitable alternatives.  Pumice has similar abrasive properties to bath brick, which may be of use.  Because of the use of talc in edge treatment it may be more commonly available in binderies.

If you want your very own bath brick, Glastonbury Reclamation regularly has them in stock.

I have read about another method of degreasing a gold cushion, and that is wiping the cushion with the rouged tissue paper from an empty book of leaf. I believe the rouge used in gold books is jeweller’s rouge, which is finely powdered ferric oxide. It makes sense that if the rouge stops the gold sticking to the tissue it will also stop the gold sticking to the gold cushion. I have a vague recollection of hearing Peter Geraty mention this and have read about it in books about gilding, but have never seen it used in practice by a bookbinder.

Survey of bookbinding authors and their recommendations, where found, for the size of gold cushions, the covering and padding materials, and cleaning substance.  Covering material can assumed to be rough calf or goat, but if an author is specific it is noted.

Some current commercially available gold cushions.

• USA Talas (Walkron made in Germany), with straps and shield 6x10in $65.70US
• UK Wrights of Lymm, with straps and shield no size details £23.94
• Australia Gold Leaf Factory, goat no shield 230x145mm 9×5.7in $38.39AU
• UK Hewit & Sons, goat no shield 300×150 12x6in £18.36
• Italy Manetti, with straps 280x180mm
• Germany Schmedt, with shield and straps 150x255mm €62.66
• Italy Dal Molin, 180x280mm €25
• France Eden Workshops, 6x9in £39.99
• Brazil – please let me know if there is a supplier

Straps means the gold cushion have hand straps underneath so it can be held like an artist’s pallet.  These gold cushions are presumably aimed at gilders who work standing up.  Shields are also common for the same type of gilders who may be working in draughty areas.

For a really over the top gold cushion, check this out.