glue

One of the most overlooked aspects I see from amateur bookbinders is their choice of adhesives or glue; many of whom rely on PVA as a ‘one-glue-fits-all’ solution. Whilst PVA is a good option for many aspects in bookbinding it almost certainly shouldn’t be used over other more suitable adhesives.

Yes, I agree that personal preference does have to be factored in when deciding how to proceed with gluing but this should always be after the number of adhesives have been narrowed down to the ‘most appropriate’ for the job. Selecting the correct type of glue and the most suitable application technique should not be overlooked, it is after all often the glue that holds the book together.

In this tutorial we will have a look at the most common types of adhesives and glues that are used in the book binding industry, along with their characteristics, suitability for different aspects of the binding process, their application techniques and even a few recipes and videos that will guide you through how to make your own – knowing this information will almost certainly improve the look and durability of your book whilst also further expanding your knowledge on traditional book-binding techniques and thus leading to a deeper enjoyment for the art (the most important part 😀 ).

Before we begin, we should first clarify the difference between the term ‘glue’ and ‘adhesive’, both of which seem to be used synonymously in today’s modern world. Glues are a ‘type’ of adhesive and are traditionally made from organic compounds and as clarified by wikipedia “An adhesive is any substance applied to the surfaces of materials that binds them together and resists separation“.

So, lets first of all have a look at the different types of bookbinding adhesives that have been used over the years and then start taking a look at the more modern, synthetic forms of glue that exist on the market today. More general info on the history of glue here.

Going back to the 19th century and the bookbinding process that existed you would likely see only two different types of glue being used: animal glue and paste glue (flour based), lets dive into each one now.

Animal Glue (also known as Hide Glue and Animal Protein Glue)

Animal glues are produced by prolonged boiling of animal tissue (the connective tissue to be more precise), after which, a process called hydrolysis starts (the breaking down of the collagen contained within the animal produce – the name derives from the Greek ‘hydro’ meaning “water”, and ‘lysis’, meaning “separation”) and a protein colloid glue is formed. The proteins extracted from this process is what ends up forming a molecular bond with the object being glued.

Common animals used to make animal glues include horses, rabbits and fish, interesting huh?

Table 1 Comparison of the Properties of Different Animal Glue Types.
Taken from https://www.academia.edu/4220133/Animal_glues…conservation

Different Animal Glue Types – Page 01

Different Animal Glue Types – Page 02

[pinterest-follow]

Animal glue, or more specifically, hide glue, is a truly reversible adhesive which makes it very common in book restoration projects and is readily available online in granule, powder or flake form. Amazon.com’s search for ‘Hide Glue’ brings up some interesting results…

Hide Glue – Produced using the same process as animal glue but using only the skin of animals

Used by the Egyptians as a form of furniture glue since circa 2000 BC. It was used with rising popularity up until the mid 1900’s when synthetic adhesives took over. It is however still used today by wood-workers, furniture restorers and in the production of musical instruments.

Two of the main advantages to using hide glue are its quick setting times and the fact that it’s re-workable, allowing people to re-heat the glue, make required adjustments and leave to set whilst maintaining almost the same strength as it was before. Hide glue can also be injected into joints or cracks as a form of filler or to ‘re-join’ materials together (Guitar Headstock Crack Repair Process Using Hide Glue) – the removal of old glue in this process is not required as hide glue bonds well with itself.

As with all glues, hide glue has its disadvantages. It’s not waterproof, the smell can be quite off-putting and it can take a long time to make from scratch.

If one is to make their own hide glue then they should make sure not to heat the glue past 100°C (boiling point) else you will start to destroy the protein strands that will result in a weaker bond when the glue has dried.

If you are making hide glue from dried sources (flakes, granules etc), make sure to only melt down what is needed and not to repeatedly re-melt/reheat the glue which causes yellowing and greatly decreased viscosity and strength. Animal glues are graded by viscosity in millipoises and jelly value in Bloom grams.

Interesting fact: When horses are put down you’ll often hear people say they have been “sent to the glue factory.” – this is where to phrase derived from.

Making Hide Glue a Video from thepathfindersschoolll.com
(also see this video on hide glue)

[youtube-subscribe]

Isinglass – a pure, transparent or translucent form of gelatin

Isinglass can often be used in the bookbinding process but it more traditionally used for clarification in beer brewing and the fining in wine-making. Isinglass is produced from the swim/air bladders of fish (as sturgeons). After the extraction of the fish parts they are dried and ground up, later to me mixed with warm water (usually around 45°C) to form a paste ready for application. Gum tragacanth, dissolved in water can often be used to strained isinglass solution to act as an emulsifier. An ethanol-water mixture can be used to re-activate Isinglass.

Get the Equipment You Need to do the Job Properly!
(Click image for more product details)

Glue Brush

Rabbit Skin Glue

Hide Glue

Mini Foam Rollers

[amazon-more-related-products]

Additional Animal Glue Resources

• Informative post on Animal Glues by Emily Carr University of Art & Design
• Animal glues: a review of their key properties relevant to conservation
• The Chemistry of Filled Animal Glue Systems (Scientific Research Paper)
• Hide Glue Production Article
• Properties of Animal Glue
• Animal Glue and it’s uses on Wikipedia
• Hide Glue FAQ
• Comprehensive Book Binding Adhesive Info at WA Bookbinders
• A good read on the history of glue
• A few tutorials and recipes on how to make your own Hide Glue: Source 1 (best) | Source 2 | Source 3
• Information sheet on using animal glue during the bookbinding process by Brookfield Engineering
• A Recipe for Rabbit Skin Glue

Wheat Paste

Wheat paste is one of the primary types of glue used in bookbinding due to its high adhesion properties, ease of making, ease of use, reversibility, versatility, archival stability and because of the toxic-free, cheap ingredients used to make it; this makes it a common choice for bookbinders and book restoration experts all over the world as well as the #1 choice for pasting up flyers on walls and buildings for those looking for alternative ways of promotion.

Wheat paste has been used for over 300 years to bind materials to paper, binding board and even leather, to which it binds very well. Whilst the adhesion properties of wheat paste is high, depending on the project, many book binders decide to add PVA glue to increase its strength. Methyl cellulose can also be added to delay the setting time of the glue without compromising its strength, this is common when working on intricate or large projects.

You will find many instructions on the internet that tell you to use all-purpose flour or even bread flour to make bookbinding wheat paste and whilst this is OK for amateur or craft projects it’s definitely not recommended for use on professional bindings or restoration projects and here’s why…

All purpose flour, pastry flour and bread flour all contain high levels of gluten (a great easy-to-read technical document (PDF) on what gluten is here). Even though it’s the gluten that is responsible for the adhesion, too much gluten in your paste can actually attract insects and thus lead to the eventual decay of the book, this is especially true for any archival projects one might be working on. For this reason I always make wheat paste from cake flour (protein content 7-8%) and some low gluten forms of pastry flour (8.5-10% protein content) which contains the least amount of gluten.

If you are unable to purchase cake flour at your local supermarket you might be able to find it in art stores in small quantities but often it is priced MUCH more than what you could pay for it elsewhere. Many art supply stores will also add acidic preservatives to their flours so make sure you ask before purchasing as some preservatives can often lead to unexpected ‘damage’ to books and paper a few months or years down the line.

For those interested: Alum, formaldehyde and even clove oil can be used as preservatives to make wheat paste last longer but could be hard to source.

Note that wheat gluten and wheat starch are NOT the same as wheat flour. Various tutorials and recipes on the internet will use them interchangeably but they are all different though can often have very similar results when used as a binding paste.

Wheat paste will generally only last for 2-4 days depending on how it is stored so it is recommended to only make small batches. Temperature, humidity and light all affect wheat paste so if you must store it make sure to put it in an air-tight container in the fridge.

Making wheat paste is a simple affair and whilst ingredient quantities and recipes may differ slightly, they will all have (at least) flour and water.

My personal Wheat Paste Recipe

• 1 part acid-free cake flour
• 5 parts distilled water
• non-metallic (none-stick) pan
• fork or whisk

Directions

• Slowly add a 1/3 of the water to your pan along with the cake flour whilst mixing continuously by hand with a fork or whisk
• When all the lumps are gone, slowly add the rest of your water to the rest of the ingredients and continue to mix until your paste is consistent (it should look a little like milk)
• Next add your pan to the stove and heat at a medium temperature until it comes to the boil
• Immediately after boiling give the mixture a quick stir and reduce to a low heat and simmer for 30-90 seconds (depending on how thick you want the paste)
• After simmering, remove from heat, give it one final stir and leave to cool
• If you find that your mixture has lumps then you might want to pass it through a fine sieve a couple of times, this is better done whilst the paste is hot.
• (I normally stir the mix a couple more times whilst it is cooling to maintain the consistency throughout but this is optional)
• After mixture has cooled you should have a semi-translucent wheat flour paste ready to use on your book arts projects.

If you wanted to experiment with adding additional ingredients to ‘enhance’ the adhesive properties or extend the lifetime of your paste then this instructables post has some more info. ** NB: I do not recommend adding any more than the above recipe outlines but why not experiment?! **

A good post on the suitability of using wheat paste on various parts of the book during the binding process.

A pretty good instructional video on how to make wheat paste

[youtube-subscribe]

Additional Resources

• How to Make Starch Paste Using Microwave
• Wheat paste info on Wikipedia
• Making decorative papers using paste and pigments 😀

PVA Glue

PVA glue (known also as: wood glue, white glue, carpenter’s glue and school glue) was discovered in Germany in 1912 by Fritz Klatteis and is short for Polyvinyl Acetate, a polymer emulsified in water. PVA is a very popular glue in modern bookbinding practices and arguably the most popular adhesive that exists on the market today.

PVA gains its strength when the water molecules evaporate from the liquid glue causing a repolymerization into a long chain molecule. This process reverts its molecular structure back to its previous state and thus increases its strength. When used with woodwork projects, and if used correctly, PVA glue can often be stronger than the wood fibres or the wood it is binding together.

PVA is known to be biologically inert and thus none-toxic; as such you can technically eat as much as you want and not get sick, though not advisable for obvious reasons.

PVA glues are used more by European bookbinders than their American and Canadian counterparts who still tend to prefer their natural alternatives (e.g. animal glues, see above). PVA is popular with bookbinders due to its relatively fast drying time, none-toxicity, reasonably long shelf life, availability, low cost, high flexibility and the fact that it dries clear. PVA can also be mixed with various other substances to increase its coverage, lengthen it’s drying-time (Methyl Cellulose), change its characteristics or purely for aesthetic purposes (e.g. adding dyes to the glue).

Some interesting facts about PVA Glue

• All PVA glues are designed to work on porous materials only
• PVAs need pressure to adhere correctly
• PVA glue is a type of aliphatic resin (also known as yellow carpenter’s glue)
• PVAs are water based and can be cleaned up easily with soapy water
• PVA glues, in general, are not water proof
• PVA sets best at room temperature in a place with good air circulation
• Yellow tinted PVA glues have a shorter shelf life than white PVA glues.
• Generally all PVA glues are the same in molecular structure with only *very* slight differences depending on what application they were designed for – don’t pay more for ‘special’ types of PVA, their pretty much all exactly the same
• The degree of polymerization of polyvinyl acetate typically is 100 to 5000 😉

PH Neutral / Acid-Free PVA Glue

Common among professional bookbinders are the acid-free ‘ranges’ of PVA glue, developed specifically for the Book Binding, Conservation and Book Repair Industries and as the name states, offer a pH neutral chemical make-up perfect for bookbinding or restoration projects. Whilst there are many different types of acid free PVA glues on the market, I tend to use Books by Hand pH Neutral PVA Adhesive >> which also happens to be reversible (just moisten with water) and more flexible than other PVA glues (both normal & pH Neutral) I’ve used in the past.

In general, pH Neutral and Acid Free PVA glues are formulated specifically for preservation projects because such qualities are not normally required when dealing with general woodwork or other day-to-day craft work. Because of their slightly different chemical composition you’ll find that pH Neutral PVA Glues often will not yellow or become brittle over time which will happen with normal PVA Glues; they also seem to offer better film forming properties which helps when you are dealing with light cloth or delicate fine papers.

Common uses of PVA glue include sticking paper to paper, paper to binders board, sticking binders board together, or sticking leather or cloth to binders board.

Methyl Cellulose

Methyl Cellulose (also known as methyl ether and methylcellulose) is none-toxic, none digestible, chemical compound derived from cellulose (plant fibers); it has a neutral pH, dries clear and provides very flexible bonds. In bookbinding, Methyl Cellulose has many uses, the main one of which is as a mild glue for delicate works such as affixing silk to boards/paper or for book restoration repair. Due to the fact that methyl cellulose is reversible, dries with a matt finish and isn’t affected by extreme temperatures makes it ideal for use when dealing with archival work.

Disadvantages of Methyl Cellulose

• It is not suitable for use in high humidity
• It’s not particularly strong (much weaker than PVA)
• Limited availability

Methyl Cellulose can also be mixed with PVA glue to help give more ‘slip’ and prolong its drying time without affecting its strength. MC is normally purchased as a granular white powder and has an infinite shelf-life (I tend to buy mine for cheap in bulk here off Amazon.com).

Another less common use for Methyl Cellulose is to help loosen and break down old glue from spines, bookboards, paper linings etc. You can also use MC to thicken water baths ready for marbling paper or fabric.

Methylcellulose is the main ingredient in many common wallpaper pastes on the market and can be easily washed off with water. It’s also used as ‘sizing’ (http://en.wikipedia.org/wiki/Sizing) in the production of paper and textiles (applied during the production of paper and canvasses to reduce the absorbtion of water by minimizing the materials absorbtion through capillary action).

Methylcellulose should be mixed with cold or warm water, it does not mix well with hot water. Please see Directions on How to Mix Methyl Cellulose Correctly and its Various Applications.

Further Reading: http://bigjumppress.wordpress.com/2013/05/08/oh-my-god-im-out-of-glue/

History of Adhesive infographic

Click the image to the right to view the full info graphic. >>

NTI Data Products – The History of Adhesive from Horse Glue to Elmer’s to Nano-tech

Hot Melt Adhesives

I hate hot melt adhesives. I do not think they have a place in traditional bookbinding projects. If however you’re looking for information on it, this might help 😀