Eventually, I’ll get around to putting the shingles on the roof. That is, once I finish the interior and decide if I’m adding dormers. But, details aside, that whole shingle on the roof thing has to happen. I’ve got the shingle lines drawn, so it’s really just a matter of gluing them on.
I say that like it’s an easy task. It might be. But I’m sure it will go sideways. Just wait.
The Keeper’s House instructions recommend using liquid nails for the shingles as opposed to tacky glue or any other glue, which is interesting, because so far, I’ve been using tacky glue on everything else and it seems to be working out just fine. So why the emphasis on liquid nails?
Since I’m not going anywhere right now, I decided to investigate if it’s better to use wood glue or liquid nails for the shingles. And, quite frankly, in general. Have I made a mistake using tacky glue? Should I have used liquid nails from the start? Turns out, there’s more to wood glue than picking a brand, and liquid nails aren’t just glue.
What Is Wood Glue?
Not to be obvious, but wood glue is glue made specifically for gluing wood pieces together. I know that’s dumb, but it’s also the truth. What’s interesting about wood glue is it’s glue that’s designed specifically for wood. Wood glue is thin. As it rests on the wood surfaces while curing, it eliminates any gaps that might occur with other glues.
As a quick reminder, when glue dries, it creates a bond between the two surfaces that you’re trying to glue together. The fewer gaps between the two surfaces, the tighter the bond. (There’s a joke in there somewhere. I just know it!)
For the most part, glue is glue. The real difference among glues is how they dry (fast, slow, clear, etc.) However, when it comes to wood glue, there are some subtle differences I didn’t know existed.
Turns out, there are (at least!) five different types of wood glue. And, like all things, they each have their pros and cons.
PVA glue (AKA polyvinyl acetate) is the most common type of glue. It’s found in white glue, yellow glue, and bottles called “wood glue.” PVA is really just the colorless odorless material used in glues (or, technically, adhesives — more on that in a minute).
PVA glues are fantastic for gluing wood to wood, but not so fantastic on nonporous items, like metal or plastic. They also don’t stick well to other glues, so if you’re using PVA glue to fix something that already had glue on it, it probably won’t work.
PVA glues are water-based. As the glue cures, the water evaporates into the air (or sinks into the wood), and what’s left behind is the glue bond.
And, if you do go the PVA route, you need to clamp the edges together until they are dry (like this):
The thing about PVA glues is that they aren’t that strong. If the pieces you’re trying to bond move before the glue is set, you’ll weaken the bond, making it more likely that the glue bond will fail early. So, if you’re using this kind of glue to glue together edges (say, the outside walls of a dollhouse), the glue alone likely won’t support the edge, making your dollhouse more vulnerable to falling apart.
Lastly, PVA glues don’t dry clear, making it a pain in the butt to stain or paint.
Polyurethane glues are water-activated, which means it needs water from the wood (or other object) to react with the glue to cure and form the bond. As the polyurethane glue cures on the wood surface, it expands into the wood pores, reacting with the moisture in the wood. The reaction causes the glue to expand, filling any voids in the wood, creating a strong bond.
The problem with it is that it can “over-expand,” (as much as three times your starting amount) if you apply too much. Also, some people describe polyurethane glue as more like syrup than glue, making it easy to apply more than you want. And, while the expansion can fill gaps in the wood, that doesn’t make the bond any stronger. It just makes the wood look “prettier.”
If you over-apply the glue, don’t assume your product is ruined. You can wipe the excess off with a solvent. However, it’s better to let the glue dry, then remove the extra with either sandpaper or a chisel. However, you have to use a light touch when going the sandpaper or chisel route. Once the polyurethane glue dries, it’s hard to remove (which is kind of the point!).
Polyurethane glues, once dry, are easier to stain and paint. You’ll have to sand them first, though, to create a rough surface that the paint can adhere to.
One of the main drawbacks of polyurethane glues is that they can dry and harden in the container. This happens when moist air gets trapped inside the container, which causes the curing process to start.
In some respects, there’s no way to avoid this. Once you’ve opened the glue and used some, you’re going to end up with an air gap that traps the air. To impede the curing process, pour a little bit of mineral spirits into the container when you aren’t using the glue. This will stop the reaction. Just make a note on the bottle that you did this, and pour the mineral spirits off before you start using the glue.
Epoxy comes in two parts, a resin and a hardener. Mix them together to create a strong, water-resistant polymer. Fun fact! Some epoxy is so water-resistant and strong that they are the go-to for boat builders (no word on if that’s hobby boats or real-life boats).
Apparently, you can mix in different substances to change what the epoxy does. For example, you can mix epoxy with silica to make it thick, then use the epoxy to glue joints and fill voids. Throw in some color, and you can tint it to fill an exposed crack in something. And, because the bond is so tight, you don’t have to use a tight clamp or even clamp your project for very long.
The problem with epoxy, though, is that you have to mix them yourself. I don’t see this ending well for everyone. Not only do you have to mix them yourself, they are messy, making them a pain to mix up. And, you have to get the proportions just right, otherwise, your epoxy concoction won’t work. Plus, once you mix it up, you’ve got to use it or lose it.
Even though epoxies have a long cure time, two to five days (and up to two weeks) to cure fully, which means you may not be able to paint or sand it while you wait), there’s no way to stop the curing process once it starts. And, that curing can be hazardous.
While epoxy cures, it generates heat. That’s normal, and kind of a good thing since it helps speed up the curing process. But, if you use epoxy on a small area, the heat the epoxy generates may not be able to dissipate. This creates a problem. The hotter the epoxy gets, the faster it cures, which, in turn, creates more heat, which makes the epoxy cure faster, and so on and so on.
If you’re not careful, you can melt or burn your project. Worse, if you use a lot of epoxy, there’s the chance you could start a fire. Always, always, always use epoxy with caution and follow the manufacturer’s instructions.
This has nothing to do with hide-and-go-seek (sadly). Hide glue is made from, you guessed it, animal hides. Depending on your age, you may know the old joke about sending washed up horses to the glue factory. And, apparently, there is some truth to that. But, put aside how you might feel about hide glues while we discuss its merits (and downsides).
Hide glues don’t creep, meaning it doesn’t seep out of the joints.
The bond is super strong and long-lasting. You can find hide glue holding together antique furniture, for example, and not because it was repaired recently. Hide glue is also easy to remove compared to other glues. You can steam it off if you mess up and start over.
That said, well, you might be opposed to how it’s manufactured. And because you can make the glue soft again with moisture, you run the risk of your project falling apart if it gets wet or you keep it somewhere damp.
Also, it’s hard to use. One of the advantages of hide glue is that you can control how tacky the glue gets (meaning, how sticky it is when you first start using the glue). You do this by heating and mixing the glue until you find the right consistency that gets you the tack you’re looking for. That, of course, takes time, practice, and patience. It’s also why you won’t find true “hide glue” in the hobby shop. It’s not the kind of thing you can bottle and sell in a mass-market kind of way. That’s not to say they aren’t out there, but they are very hard to find.
Cyanoacrylate glue (AKA super glue)
I’ve written about this before, so I won’t get into it (link). But, in short, this is super glue. You won’t use it very often in dollhouse building (or woodworking), but it’s a great way to temporarily join two pieces of wood.
What Is Liquid Nails
You’ll notice that nowhere on the above list did I mention liquid nails. That’s because, as I was researching this, I learned that liquid nails is actually a name brand (like Kleenex!). So, I guess I should say, “Liquid Nails.”
Once I figured that part out, I decided I should learn exactly what Liquid Nails is — kind of like how Kleenex is a facial tissue. And, it turns out that Liquid Nails is construction adhesive.
What Is Construction Adhesive
Ah, yes. So, now we’re on to the real question. What is construction adhesive?
Seriously. It’s just another version of glue. Well, actually, bonding agents, which is a broad category. When you’re trying to figure out what construction adhesive to use, you need to look closely at your project and the adhesive. The information on the can, tube, whatever, will tell you what you need to know. Like, are you gluing on a porous or nonporous surface? Knowing that information will help you decide.
That said, there are some common characteristics that all construction adhesives share:
- They have a thick consistency, like paste
- Good at filling gaps
- Tend to stay flexible once dry
- Water-resistant or even waterproof
- Take about 24 hours to cure
Beyond that, just read the label to make sure you get the right one. A construction adhesive that says “for ceramic tile” won’t do wonders for your wooden dollhouse project.
How does construction adhesive work?
Construction adhesive works pretty much like any other glue. Apply to the surface, press the two pieces together for a minute, and let go. You can clamp it if you need to to help it set, but you shouldn’t need to. That said, even though construction adhesives cure in about 24 hours, it may take as much as a week for the bond to reach full strength.
Wood Glue or Liquid Nails (or Construction Adhesive)
So, which one should you use, wood glue or liquid nails?
Don’t hate me, but it depends on the project!
That said, for most of your dollhouse needs, I’d argue you should go with wood glue. Why? It’s made for gluing wood. What more could you need?
Well, a fast drying time, for one. When I finally put the whole house together, I had issues with tack time. You should have seen me sitting there holding the pieces in place and waiting, waiting, waiting until I could let go. Then, I had to tape everything together until it dried to a firm hold.
That’s why I can see the argument for using construction adhesive to do, for example, the dollhouse shingles. If the glue isn’t tacking quickly, I’m going to end up with shingles sliding off the roof. Plus, how the heck would I clamp something like that?
Answer: you don’t, hence the argument in favor of liquid nails for the roof. It’s pasty, so it won’t run down the roof if you put on too much. And, you don’t have to clamp or hold the shingles for very long, so your arms don’t get tired!
Deep thoughts, right here.
Another Purchase (Eventually)
I have a feeling that when I get to the shingles, and everything is reopened, I’m off to get some construction adhesive. I may attempt one line with the tacky glue to see what happens. I might be wrong, but I can see the shingles sliding off the roof in no time. Like melting snow.
What about you? What are your thoughts on wood glue or liquid nails? Or, both? Do you use both? Ride or die for one? Let me know in the comments!