Intro: Welding Capri Sun Pouches
I'm a little miffed at Kraft for heavily marketing these things because they aren't recyclable. So instead of doing something about it, they engaged in a distraction campaign with their Terracycle program. But at least you can earn money for your kids school which is cool.
Unfortunately I can't get completely miffed about it because I love a couple of flavors of capri sun. Plus it's handy as heck to pop them in the freezer then pop them in my lunch box cooler. They serve a dual purpose here. They keep things cool in the lunchbox cooler, and by the time lunch is around they have thawed out.
The other thing I love about these things is all the cool things I've seen people make with them. Wallets, purses, bags, you name it. Just do a google search for "capri sun projects" or "DIY capri sun". You'll see what I mean
I have a bit higher aspirations than that. I want to try making an umbrella or a tent out of them. But the tent might be a bit ambitious. Most people sew them together with thread, fishing line, or upholstery thread. Or they will tape them together with Duct Tape or Gorilla Tape. I wanted to weld them together.
At first I looked into how they do it industrially. Apparently they either use microwaves or ultrasonic welding. Do-able, but not for everyone. Certainly not with parts I had laying around the house, and certainly not cheap.
In the end I found a soldering iron or wood burner works like a charm.
Step 1: The Science...
So a little google-ing and I found what they are made out of...
What is CAPRI SUN packaging made from? Is it recyclable?
CAPRI SUN pouches are polyester-reverse side printed to aluminum then laminated to polyethylene (a plastic polymer). Unfortunately, this packaging is not recyclable.
So it looks like a laminate of aluminum foil and polyethylene. Ok fine. What is the melting temperature of polyethylene? A quick trip over to Wikipedia and I had my answer. I love Wikipedia, best invention ever. The nobel prize should go to the guys that invented it. They are certainly more deserving than a couple of the past winners.
For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 130 °C (250 to 265 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (220 to 240 °F).
Ok so the melting point is somwhere between 220°F (115°C) and 265°F (130°C). Ok, that shouldn't be a big problem. I think clothes irons only get up to about 200°F so I'm thinking an Iron wouldn't work.
Step 2: Trying to Use the EuroSealer to Weld Capri Sun Pouches Together
My first thought was to use a EuroSealer. It's that gadget that was shown on infomercials a while back. It reseals potato chip bags, and it really works too. It's on the left in the picture below.
You can pick them up for cheap on eBay. I did. It, unfortunately, doesn't have the heat needed to weld Capri Sun pouches. So I thought I could open it up and remove the resistor in it (if there is one) or put more voltage through it by rigging a larger battery source. It uses two AA batteries so it has 3volts. I thought of hooking it up to 4.5 volts and 6volts to see if I can get more heat out of it.
I still think this is worth trying I just haven't gotten around to doing it yet. But I'll update this Instructable when I do.
Step 3: Building a Capri Sun Pouch Welder.
My next thought was to take some nichrome wire out of an old space heater, toaster, or hair dryer. Wrap the nichrome around a metal rod, then put that inside a metal tube wrap fiberglass cloth around the tube, to prevent sticking. Then use that to clamp down on a couple bags to weld them together. I haven't gotten too far with that project yet.
Ok so I tried taking a stainless steel bar, heated it up on the electric stove burner (on high) then I tried to clamp it down over 2 overlapped Capri Sun pouches on a wooden cutting board. It was a surprising failure. I could hear the remaining liquid in the pouches searing, I could see the plastic pouch melting. But no matter how hard I pressed I couldn't get the two pouches to weld together.
Stay tuned for my next attempt along this line. I'm going to take a copper pipe to try to weld pouches together. What I learned from this last attempt is that I think I need something flexible underneath the pouches along the seam to help compress and set the weld.
One commenter on this project gave me a good idea. Perhaps using some material between the bags to act like solder flux would aid the welding process. The trouble is, what that material might be. I'm thinking of a lower temperature melting point plastic.
Step 4: Using a Soldering Iron or Woodburner to Weld Capri Sun Pouches
Then I stumbled across an instructable here that used a soldering iron to weld plastic bags together. Brilliant! I thought. I've got a combination soldering iron/woodburner for Christmas a while back. It actually frustrates me to use it as a soldering iron because it doesn't really get hot enough to melt some forms of solder. So I'm thinking it's a touch on the cool side of a soldering iron.
Another quick trip over to Wikipedia and I had the information about how hot a soldering iron gets:
Lead-based solder uses 250 °C to 280 °C or 300 °C while lead-free soldering needs a higher temperature, about 350 °C to 400 °C.
So a soldering iron gets plenty hot for welding Capri Sun Pouches. I just have to be somewhat quick and not leave it in the same place very long. Now my Soldering Iron/Woodburner comes with a bunch of different tips, so I selected one that was flat. This tip actually broke when I was using it, but they are cheap to get replacements (or so I hope). But it still had a flat side on it and it continued to work for my purpose.
Now it takes a bit of practice to get this technique down. You have to figure out the right speed with which to drag across your seem without making a hole, but still keep it in place long enough to melt the Polyethylene. The pictures below are actually my second attempt so it's easy to pick up the technique. The secret is lots of steady pressure, and it works best if you weld both sides. But when I was done I had two Capri Sun pouches welded together. The seam was water tight and wouldn't pull apart. Brilliant!
So commence the making of things with Capri Sun Pouches!
Step 5: Using a Clothing Iron to Weld? Not So Much.
Ok I know I did some research on this before, but I almost never believe anything I read. Plus I had some spare time to try it out. I tried using a regular clothing iron to weld CapriSun Pouches together and it was a bust. I cranked the thing all the way up to it's hottest and no matter how I tried I could not get it to weld the pouches. I tried using the side of the iron and pressed down very hard first. That didn't work. Then I tried taking a clothing hanger and cut pouch sized strips off of it put it on the pouches then applied heat and pressure to it with the iron and it was a whopping bust.
Conclusion: A standard clothing iron just doesn't have the heat needed to weld CapriSun pouches together.
Step 6: FoodSaver Seal-a-meal on Capri Sun Pouches
It just occurred to me to try my Food Saver Seal-a-meal vacuum packager (model VAC 1075) to weld Capri Sun pouches. I mean it seals heavy plastic bags, why not Capri Sun pouches? Well the experiment was unsuccessful. I tried it on two pouches and pressed down hard and put them through 3 sealing cycles, and they barely even got warm. Darn I was really hoping that one would work.