Wood is definitely one evergreen material with unique patterns of grain and astounding tones to fall in love again and again. The way it looks and works has earned it huge praise from the very beginning of its usage. This beautiful building material is also relatively easier to use. The surface is soft and porous, which gives fantastic flexibility to easily join multiple pieces.
But whether you are using a nail, screw, or glue to complete the joining, this will result in different outcomes. Today we are focusing on how does wood glue work for joining wooden pieces together.
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How Does Wood Glue Work Depending on The Types of Wood Glue
No matter if you are using glue for wood join or furniture repair, it needs to have a good holding capability. In the case of joining woods, there are basically three types of wood glue that woodworkers use. Let’s walk through each category to find out how well does wood glue work and which one should you prefer more for use.
PVA Glues – The Most Common Type
Let’s start with the most commonly used, simple and yet very useful woodworking glue. It’s the yellowish looking PVA wood glue. With the proper usage, you can get a fantastic solid bond between wooden pieces through this. It’s ready to go from bottle glue that is relatively cheap and also super simple to clean up.
The PVA glue is a water-based formula that needs to diffuse into wood. It can also work by evaporating into the air. The left-behind particles play flexible polymer film making duty that basically creates a link. The glues that come with higher initial tack will perform better at holding parts and orienting any slide out while you try to clamp.
However, to joint woods and get expected results there are a few things the user needs to ensure. The first one is about managing tight joinery as well as a solid clamping pressure. The strength of the joint heavily depends on glue-line thickness. The more you prepare joint and clamp with proper snug and uniformness, better will be bond.
Uniform pressure clamping will result in a perfect squeezing of glue to get rid of excess and spread it evenly. With the right distribution, it will penetrate into wood better. The water volume will start reducing and glue will also begin to shrink. On the top, clamp pressure will make sure glued surface is tightly together.
The minimum time for clamp can be a varying factor though. It’s somewhere between 30 to 60 minutes typically. The longer you leave it for clamping, better is going to be results. After 24 hours, the glued joints will reach its maximum strength.
However, how strong is wood glue going to be will highly depend on the wood you are using. For any load-bearing wooden project, using PVA glue might not be a very good idea though. Because it’s not structural and also fairly flexible which is one good key point for most wood projects. Unfortunately, except the load-bearing ones.
Polyurethane Glues – The Easy to Stick & Hard Drying Type
Next is polyurethane glue that can be a pretty good substitute for the first type. In some jobs, it’s definitely superior to the PVA glues. You can use it for outdoor projects as the glue has some exceptional water resistance ability.
Similar to the PVA, polyurethane glues are strong and also one-part. And so, it works best for close-fitting joint tasks. It surely requires a good clamping. You need to apply this at room temperature for the right results. If the temperature is between 5 to 10 degrees Celsius, there’s a high chance of facing spreading difficulties as well as slower curing.
With polyurethane glues, you need water activation for it to work. Once you apply this glue in wood joints, it will start to cure and expands. The expansion happens into pores and then it reacts with moisture.
This reaction creates a strong bond to hold things together. And so, using polyurethane for outdoor woods that are slightly damp will provide you with a good ending result. However, in case of using dry wood, you need to wipe or mist it for adding moisture before using polyurethane glue.
Polyurethane glue is also harder drying than PVA. And for this level of solidity, you find polyurethane better at creep proofing. There’s less chance of clogging as well as loading up sandpaper. For end grain, polyurethane works stronger than PVA. However, in the case of long-grain joints, PVA provides better results.
The solvent-based stain taking capabilities of polyurethane is also a notable feature. It’s pretty helpful when you want to hide the glue joints. And that’s quite not possible with other PVA or epoxy glues. Polyurethane is also good at sticking well with most materials including nonporous ones. For example, if you are willing to glue unfinished wooden trim, polyurethane will definitely do the trick.
Epoxy Glue – The Versatile Option
Finally, let’s talk about the problem solver glue that is amazingly versatile. It’s the epoxy glue and usually, it comes in two parts. It can be resin and hardener. After mixing, it takes a form of the polymer. And that form plays as a strong and water-resistant holding agent.
You can use epoxy for structural needs. It also works great in gap-filling works. Even underwater or in moderately wet conditions, most epoxies are well capable to work enough. Boatbuilders usually love epoxy glue for that reason.
The most adaptable type is definitely marine epoxy. This is a general-purpose glue that seals end grain perfectly. You can mix it with thickeners such as silica to make the formula work fantastic for wood joints. It can also work for bonding wood laminations.
The cure time may extend or accelerate depending on what thickener you mix with epoxy. Epoxy can work well in minimal clamping pressure too. Here you don’t aim to make tight glue lines. The clamping is just for ensuring a proper alignment. The epoxy cures while glued surfaces contact each other. Enough epoxy needs to be used so that the access can squeeze out from joint while clamping.
And that was all about how does wood glue work based on what type you are using. Apart from these three, there are also other high quality and superior adhesives available that woodworkers use for specialized projects. Such as hide glues, contact cement, resorcinol glues, urea-formaldehyde, and more.
However, these three are the most common ones that go hand in hand for wood joining and also for repair. So as a woodworking starter, gaining knowledge on these three sounds wiser than researching on a whole bunch of rarely used glues. Good Luck on Making Well Use of These Glues!
This is Autem Decker. Main Author of ‘TheHomeDigs‘. You may not find her on the list of top 10 contemporary Canadian interior designers, but everyone who knows her says she was born to be an interior designer.
She makes her plan in her head and draws them on her years-old dairy with a note in the corner. The way she plays with color and shape amazes us.