OBG is specifically formulated to be a gel at room temperature. It must be heated to use and the viscosity can be controlled as a function of temperature. Simply place the bottle in a pan of water with a metal thermometer and heat it up. The normal range for use is between 110 degrees and a maximum of 160 degrees Fahrenheit. Lower temperatures are useful for gluing paper, leather or cloth to wood, while higher temperatures provide deeper penetration into fine cracks and a longer working time. The best temperature for all use is around 140 degrees.

Note that OBG can be heated and cooled as often as desired without any change in the quality of the glue. Be careful not to exceed 180 degrees for any length of time.

We guarantee Old Brown Glue for 24 months from the date of manufacture.
Refrigeration will extend the shelf life, but is not required.
Old Brown Glue is not affected by freezing.

We tested Old Brown Glue with multiple freezing and thawing cycles and detected no change in its quality.

Liquid Hide Glue is not for hammer veneering. It is also not recommended for rubbed joints. If you want to hammer veneer we also sell granulated #192 gram strength Hot Hide Glue.

Using a toothing plane is part of the traditional process of working with Hide Glues.
A toothing plane levels the surface, cleans the wood and increases the glue surface area.
It is recommended but not required.

W. Patrick Edwards developed Old Brown Glue to use in his restoration business over 20 years ago, and it has become the principal glue in the shop for furniture making and restoration.

The Hot Hide Glue is still used for rubbed joints, quick repairs, hammer veneering and marquetry on an assembly board.

OBG penetrates deeply into the wood fibers on end grain, since it remains liquid and has a high water content. Therefore, we would normally add the glue (hot and liquid from the bottle), wait a minute or so and repeat the application as necessary until there remains a visible layer of glue on the surface. Clamp it right away, do not wait for the glue to gel, as that would not produce a good tight joint.

If it is modern glue you need to remove it completely to the bare wood. If it is hide glue, bare wood is preferable. Hide glue is the only glue that bonds to itself so it will bond to the old hide glue if you reactivate it with moisture.

All protein glues cure over time by loss of temperature and loss of moisture. Both HHG (Hot Hide Glue) and OBG (Old Brown Glue) are approximately 50% water and they cure over time by loss of this moisture content. That means that the moisture must evaporate into the environment, or be absorbed by the wood or pressed out by clamping pressure to fully cure over time. When working in a cold workshop with cold material there is a simple trick often used by traditional woodworkers to provide a longer working time. Take a very hot and damp cloth or sponge and wipe the glue surface of the wood just prior to applying the glue. This will deposit a thin film of water on the surface and in the pores of the wood, preventing the cold dry material from sucking the heat and water out of the glue.

The only difference between HHG and OBG is the addition of urea, which bonds with the protein molecule and reduces the gel point from around 100 degrees to around 80 degrees. Both are made with the same 192 gram strength Milligan and Higgins hide glue. HHG sets up quickly as it loses temperature, thus making it ideal for hammer veneering and rubbed joints, as well as quick repairs. Therefore clamps can often be removed in a matter of hours depending on the specific application. OBG sets up much slower and it is recommended that clamps be kept in place overnight. However, I have used OBG for rubbed glue blocks with success, as long as I do not put pressure on the assembly until the next day. Both HHG and OBG are fully cured when the moisture component is gone.

It is essential to understand that it takes a combination of both heat and moisture to “reverse” the bond. Protein glues are unique in this property. They can go from solid to gel to liquid and reverse back to gel and solid state by controlling the moisture and temperature. Think of water and how it can be either solid, liquid or gas and not change its original chemistry, which is simple H20. Think of protein glues in the same way. When the glue is in its solid state, it is dry and at room temperature. Nothing will happen to it if the temperature is raised, assuming there is no water or humidity present. When you add water, at room temperature, the hydrogen bonds of the protein molecule start attaching to the water molecule and it begins to gel over time. Now if you add heat it will eventually become a liquid and can be used as an adhesive. When it is allowed to cool and dry out it changes from liquid to gel and finally back to solid.

This process can be repeated an infinite number of times without affecting the protein itself. This is what is known as reversibility. Therefore if you want to “reverse” a wood to wood bond to repair something, you must think about what is the actual moisture content of the glue inside the joint. If it is a freshly glued surface then it is just a matter of adding heat. If it is a completely cured joint then it is necessary to add water to hydrate the protein first and then add heat. Simply adding dry heat is not enough in most cases.