What dissolves wood glue?
This is a common question. Glues have always been held together by moisture from the air or water added to them, since not all glues will dissolve in water (Casein). A lot of people are confused because they are storing their glued wood items in areas with high humidity such as basements and cabins and some exotic woods. The high moisture content dissolves the glue causing the pieces to eventually fall apart, this has confused many into thinking that some types of wood do not like glue, when in fact it is just an unfortunate coincidence that the owners area had more moisture than usual. So here’s your answer: what dissolves wood glue? Answer: High levels of humidity.
How to prevent this… Don’t store your glued wood items in an area that is going to be exposed to high levels of humidity. You can use a desiccant (drying agent) such as silica gel, but even these products will not work for long periods of time and the best solution is just to keep your wood out of areas that are exposing it to too much moisture.
As you may have guessed, it also affects your glue-ups when using hot hide glue, or any other types of water soluble glues. Moisture dissolving the glue causes it to start absorbing into surrounding objects instead. In order to prevent this you need either fresh air circulating around while your waiting for the glue up to dry, or a temperature controlled area. Using a hair dryer on the lowest setting works best, but can take up to 10 minutes depending on the thickness of your glue-up.
Tips for using wood glue …
Be sure to thoroughly mix the glue with the water before applying, it will be more effective. Adding a lot of water at once may cause separation within your container so just gradually add small amounts until you have achieved the desired consistency. If using hot hide glue, wait for it to cool down before mixing in the water or you could burn yourself. You can either use a brush to apply wood glue, or better yet a piece of scrap wood as a spreader. A paint roller might also work pretty well for larger jobs if you don’t plan on sanding any excess away.
You can speed up drying time by blowing air from an electric hair dryer onto one side of your wood while gluing up on another side (hot hide best wood glue only). When using polyurethane glues, use a brush to apply the glue. A paint roller may cause separation or dry bubbles in your finish. Let it sit for about 15 minutes before you start sanding and/or applying finish. If you need to wipe away excess wood glue that is still wet, do so while holding an old rag over top of it so that no moisture will be absorbed into the rag.
Use hot hide glue when you are going to keep your project in an area where the humidity level is normal all year. If you have a finished project that will be exposed to higher than normal humidity levels, then you should put some type of finish over it just incase. The same goes for any projects with moving parts or interlocking joints such as finger-joined furniture. These types of joints are also very fragile until they have completely dried out and usually require clamps rather than tape. Tape can leave behind an indentation which will show up once the piece has been varnished further causing it to look like there was a defect. So remember no matter what type of wood glue you’re using , always keep your project in a normal humidity area.
Use polyurethane glue on projects that you can not afford to finish as soon as the glue-up is done, such as complicated joints or items with finger-joints. These types of joints are also very fragile until they have completely dried out and usually require clamps rather than tape. Tape can leave behind an indentation which will show up once the piece has been varnished further causing it to look like there was a defect. You may need to use some type of release agent if you are using veneer’s so that it does not stick to your wood and cause tearing when gluing (hot hide glue only). But make sure that it does not contain wax, as it will prevent the glue from adhering properly.
Evaluate when to use hot hide glue, and polyurethane glue …
Hot hide glue can be used on projects that are going to be exposed to higher levels of humidity such as humid storage areas or even as book bindings. Polyurethane glues can also withstand some moisture so it is most likely better for you to use this type of wood glue if your project will not be completely enclosed by a finish. But remember that high humidity could still cause problems if the inside of any object is wet (ie: finger-joined furniture). Once again these types of joints are very fragile until they have completely dried out and usually require clamps rather than tape. Tape can leave behind an indentation which will show up once the piece has been varnished further causing it to look like there was a defect.
Wood glue is measured by volume and the most common measurements are 1 quart, pint, and a half-pint. The way wood glue is made today it will take approximately 6 to 8 ounces of hot hide glue mixed with enough water to produce about 1 quart or 4 ounces of polyurethane glue mixed with enough water to produce 1 quart. Since there are so many different types and brands available on the market today you should use their mixing directions for proper measurement.
If using hot hide glue , add your water before adding your glue into your container because if you add water right away, the mixture might become too thick . You can try adding more water in order for it to get thinner, but be careful not to add too much.
Once you have your mixture ready, place the glue and water container inside a pot of water which should be hot but not boiling. Keep a thermometer on it so that you can keep checking the temperature. The actual temperature that you want is from around 140 to 150 degrees F. If kept at this temperature for long periods of time it will still work properly, but if exposed to higher temperatures than 150 degrees F., it may be more difficult to get a good bond and using plastic type containers might also cause some problems with warping due to heat expansion.
PVA or Polyvinyl Alcohol is also known as water based glue. PVA glue can be used to make a strong bond but the problem with this type of wood glue is drying time . This type of adhesive will not dry for a couple weeks, so it probably isn’t best if you’re in a hurry (it won’t hold together that long).
Another difference between hot hide glue and polyurethane glues are setting times which are usually 10-30 minutes for hot hide glue then curing time(s) over 48 hours depending on the strength needed. When using wood glue, make sure you have enough clamps at hand and that you place them evenly across your project area before applying any pressure because you can leave indents, and if you are using an open-grained wood like oak or maple the grain can be left crushed. This will not look good when sanding your projects after it dries, so keep this in mind.
Wood glue is usually a brownish colour resembling peanut butter once it has dried but this may vary depending on which type of brand you use. Some brands have other colours available such as yellow and or green . Just make sure that you choose one with easy clean up characteristics since often times you will find that glue sticks to anything wet like fingers, tools, etc… If there is any extra over run from your project (usually due to clamps being moved), then lightly sand off the excess rather than scraping it with a knife or your fingers as this can cause the wood to splinter. You may also want to try using mineral spirits or denatured alcohol in order remove any glue from your hands.