Introduction: Wood Bending With a Vacuum Bag
Wood bending is a really cool technique that can be used in loads of projects. Contradicting to what a lot of people think, you can bend wood relatively fast and cheap. If done right it looks very professional and upgrades the overall look of your project.
In this tutorial we will show you how you can use a vacuum storage bag to bend veneer wood. We bent a relatively small piece, this technique can be used for slightly larger project but if you want to bend really big pieces you should consider using another technique (like with a two-part mold or professional vacuum equipment).
Step 1: Materials and Utensils
As this is a relatively cheap and easy technique, you only need the following materials and utensils;
- Wood veneer; this will determine the look of your project. The thicker you want the finished piece to be, the more wood you'll need to buy.
- TIP: with the multiple layer technique, you can use cheaper wood veneer on the inside (you won't see this anyway) and more expensive wood veneer for the first and last layer. This way you don't spend more money than needed on parts you won't even see.
- Vacuum bag; we used cheap and easy to find vacuum storage bags. (this one was red but there are see-through ones as well)
- Where to find in Belgium; Action, Hema, bol.com,...
- Where to find in the USA; Walmart, Amazon,...
- Wood glue; we used a fast drying wood glue. This way the process is a lot faster (obviously) and the result will probably be better (sometimes the vacuum bag lets some air back in, so the faster the glue cures, the less chance there will be air pockets or deformities).
- Material to make the mold; you can use wood or hard foam (HDPE) to make a mold.
- TIP: use a material that you have the best tools for to cut and sand your shape out of
- Plastic wrap
- Vacuum cleaner
- Some rubber bands
Step 2: Making the Mold
With this technique you have a lot of design freedom in the shape of the mold. You should keep in mind that the wood veneer isn't infinitely flexible. You can't put it in holes or make the craziest turns. Here are some things to keep in mind when designing the mold:
- Round corners; you can't get a straight corner when bending wood veneer. In fact the chance is you will damage or snap the wood if you try. Round your corners with a big enough radius to prevent this.
- No holes in the middle of your mold; the wood will not bend into these cavities.
- Big height differences; you can't make your wood bend into deep and steep ridges. If you want a big height difference you need to make a gradual slope.
- !! Make sure you can demold !!; this is very important to keep in mind. Make sure you can slide your final product off your mold.
In terms of material; make sure the material you choose is rigid enough to withstand the pressure of the vacuum bag. A block of wood or foam is ideal for this.
To finish the mold you just wrap it in the plastic foil. Why do you ask? In case some wood glue is spilled or pushed out during the vacuum process, this makes sure your product will not stick to the mold.
Step 3: Cut the Veneer
Now you need to cut the wood veneer to fit your mold. You want it to stick out on the edges a little but not too much. This way you can trim and finish the edges nicely after the bending process is over.
The number of layers you use determines the thickness and strength of your final piece. But the more layers you use, the less flexible the glued layers will be. This means you need to take this in account when determining the number of layers and the shape of your mold.
TIP; If you cut the veneer so the wood grains can cross when put on the mold, your final product will be significantly stronger. For this technique to succeed, it is also very important that the corners of your mold are well rounded. Otherwise the wood could break.
Step 4: Apply Glue to the Wood Veneer
This is the trickiest part, you need to apply wood glue to the sheets of wood veneer. The easiest way to do this is to lay out your pieces of wood veneer and apply the glue to each piece separately. You need to apply a generous amount of glue and make sure you spread it evenly over the surface of the wood. Otherwise there's a chance you will get air-pockets when the glue dries out. You can easily use a straight edge on a piece of wood to do this
Some people like to glue one piece of veneer and stack the pieces as they go while gluing each piece on top of each other. But I have found this technique is harder, as the wood starts to deform when the glue is applied it is harder to spread the glue evenly.
Things to keep in mind;
- Apply a generous amount of glue
- Spread the glue evenly on the surface
- Glue all the way to the edges
- One piece should not be glued; this will be the top or bottom piece
Step 5: Stack the Veneer
Now you need to stack your pieces of glued veneer. You can start or end with the piece that has no glue and continue stacking the glued pieces with the glued side always facing the same way. This way you avoid a double layer of glue and possible air-pockets when drying.
To increase the strength of your piece, make sure to cross the grain of each piece you stack.
When using different types of wood for the core and the exterior, keep in mind which pieces will show on the outside so you don't make a mistake when gluing the pieces together.
Step 6: Put the Glued Veneer on the Mold
This step takes some caution. Gently bend your glued veneer around you mold. Try not to force it too much so you don't damage the wood. Here the rubber bands come in handy to hold the veneer in place on the mold.
As a last step before using the vacuum bag; cover your construction in plastic foil again. This prevents your piece from sticking to the vacuum bag.
Step 7: Use the Vacuum Bag
Time for action! Now we are going to use the vacuum storage bag to press the wood veneer against the mold. It is handy to read the instructions for the vacuum bag before using it. This is how it generally works;
- Open the vacuum bag
- Place your mold inside the bag
- Close the bag
- Open up the valve
- Use the vacuum cleaner to extract the air out of the bag.
- Close the valve
Now you just have to let the glue cure. Read the instructions on the glue you used to determine how long this process will take.
TIP: after some time the vacuum bag may let some air in. This causes the bag to lose some strengt, which may lead to a less good result. So after approximately 15 minutes, reopen the valve and extract some more air from the bag with the vacuum cleaner.
Step 8: Unmolding the Wood
When the glue has cured, you can remove the mold from the vacuum bag. To remove the final piece, just unwrap the plastic foil, remove the rubber bands and take the final piece off the mold.
Be careful when removing the final piece from the mold so you don't break anything.
Step 9: Finishing the Piece
To finish your piece, you can trim and sand the edges. You can also sand the surface and remove potential stains the glue made. You can treat the piece the same way you would with any other wooden object. You can drill, saw or sand away however you want. Finish off the surface with soft sanding paper and a wood finishing stain.
Just keep in mind the piece might not be super sturdy when working with it.
If you want to sand the edges of your piece on a beltsander, the edges might start to chip off. To prevent this from happening, you can keep the mold inside the piece while sanding it. This way the whole thing is a lot stronger and the chance of it breaking is smaller.
Step 10: Enjoy!
Now you can enjoy whatever you've made!
I hope this tutorial was usefull and that you have made an incredible piece of bent woodwork. Please feel free to comment any improvements or pictures of what you have made.