Learn to Build With Cardboard! STRONG, Waterproof and Free.

What if you could make cardboard so waterproof and so durable that it could replace wood? I'll cut straight to it. Here is my best waterproofing recipe. Apply this with a brush and cardboard becomes as waterproof as a flat duck. If you want to know the purpose for each of these ingredients and how to make cardboard durable enough to make furniture and outdoor projects, that's what we'll get to next. Hi, I'm Ben and on this channel we explore lots of DIY projects and inventions with a particular focus on making the science of such things exciting and accessible to everyone. Cardboard has got to be the easiest material to obtain for free anywhere in the world just by asking for it. Thank you so much. No problem. In composition, it's not that different from very thin plywood. And I can't stop thinking that it would be incredibly worthwhile if this free and abundant material could be easily modified at home to become useful for strong, longlasting DIY projects. As we built a mini camper in the previous video, I realized that I did not need the rigidity and weight of plywood for several large sections. But what else could we do besides buying what the hardware store has to offer? Well, let's find out and see if we can make cardboard watertight and strong enough to work as my new roof. By the way, the waterproofing techniques we'll explore here will also work on fabric and many other materials to make extremely weatherproof coatings. I think you'll like this one. You might be surprised how strong cardboard is in certain configurations. Did you know there's actually a small number of people that make cardboard furniture? And the ones who are really good at it, you would not guess that you are looking at cardboard. Even things that need to hold a lot of weight, like bookshelves. If you think like an engineer, working with the material's strengths and avoiding its weaknesses, it works. Have you seen the price of lumber? How cool is it that you can build things like this? Basically, just for the price of a coat of paint. That's a skill worth having. To start with, here's a list of basic techniques to help us become familiar with cardboard as a building material. The direction of the corrugation matters. Rigidity is much higher in one direction than the other. Sheets can be laminated together with alternating orientation to achieve much stronger panels. At five sheets thick, it's about as stiff as a sheet of drywall, but way less brittle, lighter weight, and with more insulating value thanks to the air gaps in the internal corrugation. When laminating panels, don't worry about measuring and cutting them to perfectly line up. It's much faster to paste them into a messy stack and trim it to size later. By the way, normal woodworking tools work just fine with cardboard. The ideal adhesive for cardboard is wheat paste. Make this by blending one part flour with five parts water. Then put it on the stove and heat with stirring until it just starts to boil. As it cools, it will thicken into the perfect consistency. It's extremely cheap, very strong, and long-asting when dry. Biodegradable if you get it wet. It dries clear and sticks to almost anything. Refrigerate excess paste. Add a little vinegar or clove oil to improve shelf life. Edges are cardboard's weak point. To reinforce them, cut halfway through a sheet and peel off the top layer and corrugation. Add wheat paste to the bare paper and fold it over to seal the edge. This can also be done on laminated panels for a clean look. You can easily combine cardboard with other materials. Cut halfway through a sheet and the pasted edge can wrap around wooden dowels or other objects for a secure connection. Pasting on excess paper is another method to secure wood to cardboard. Now we have a cardboard panel that can be affixed with screws by the wooden frame. The surface of cardboard can be stiffened by applying a thick layer of wheat paste. If that's not enough, you can make it truly as strong as plywood by surfacing it with multiple layers of paper bags or newspaper. I know a bunch of you just checked out because you thought, "Ah, that's just paperier-mâché, a thing kids play with in art class. " Well, so is pottery, and we wouldn't have civilization without it. Don't let what you've seen kids accomplish limit your imagination of what you could do as a full-g grown adult. Seriously, a paper shell is strong enough that you can use cardboard to build a freaking chair with normal woodlike proportions. This is one of the easiest ways to make furniture. No matter how flimsy your cardboard skills, a few layers of this natural fiberglass will make it super strong. This also hides the cardboard texture so

the surface can be sanded and painted just like wood. For joints and connections that don't want to stay in place while glue dries, use toothpicks or spot weld the joint with hot glue until the much stronger wheat paste sets up. Cardboard has surprisingly high tensil strength. A single strip 12 in wide can hold several hundred lb over a span. If you do need a bunch of cardboard pieces of the exact same size, don't measure each one individually. Find a board or some other object to use as a template. much faster. Panels can be cleanly joined together by cutting halfway through each panel and removing the corrugation. Apply wheat paste and overlap. Corrugation removal can also be done to make clean folds in the center of panels, even at odd angles. Even the flimsiest of cardboard and all the leftover scraps are still useful by grinding them into pulp and mixing with wheat paste or cement to make what's called paper clay or paper cre. This can be molded into anything and once dry it becomes rock hard. This really deserves its own video. Let me know in the comments if you'd be interested to see more on this topic. A quick way to join panels edge to face can be done by delaminating the cardboard at the edge and folding out the layers to make a larger gluing surface. Stronger still is to make a slot or dado joint by adding extra layers of cardboard to the face. Make flaps where the edges meet for the best results with glue. These are some of the tips I've thought up or seen practiced by other cardboard wizards, but I'm new at this. Help me out with more ideas in the comments. Now, this list of techniques is not to say that we should start building everything out of cardboard. I just want to remember cardboard as an option on the occasions that it might work. There is so much potential for indoor projects and furniture that could be made basically for free. That much has already been proven by cardboard furniture builders. And this very stool I'm sitting on, which I made from only cardboard, paper, and wheat paste. A remaining issue to solve is the question of water resistance. Cardboard gets super flimsy the moment it becomes wet. I experimented with so many different mixtures to find the best ways to improve the water resistance of cardboard. If you would like to help support the effort it takes to research this stuff and distill it down into a video, my Patreon link is in the description below. Anyways, one goal for my waterproof treatment was to use biodegradable ingredients if possible so that the cardboard would remain a clean, friendly material that could still be disposed of through compost. Of the two best performing options I found, one does succeed in being fully biodegradable. The second option does not decompose naturally, but it might still be worth considering for its very unique properties. First, the eco-friendly option. One of very few biodedegradable, waterresistant coatings that you can buy off the shelf at a hardware store is shellac, but I don't recommend that you do that. Canned shellac sort of works, but it's really watered down. And this little can costs more than $20. For the same price, you can buy a pound of dried shellac online and use it to make a much better mixture. These flakes dissolve in 90 plus% isopropyl or denatured alcohol in order to make a paintable solution. This sample has been coated in pure shellac. And while it does succeed at preventing water from being instantly absorbed, the water clings to the surface. If water is left on the surface of shellac for more than a few hours, it will start to absorb. It will absorb very slowly and reversibly if the coating is dried again, but just hours of complete protection isn't long enough to work for outdoor use where a solid week of rain may not be uncommon. See if you can tell the difference between a coat of standard shellac and my improved recipe, the first of my waterproofing mixtures. I think it's pretty clear where my solution has been applied. To make shellac hydrophobic so that water beads off of it is a little bit tricky, especially being limited to biodegradable ingredients. The special addition to this recipe is beeswax. Now, shellac is made into a liquid by dissolving it in alcohol. However, beeswax doesn't do that. Under normal conditions, it would just sit as a lump at the bottom of the alcohol. So, we need to use a little science here. And a word of caution. Making this recipe involves a fire hazard, and so it should only be done outdoors, away from open

flames, and far from anything flammable. The recipe is 125 g of dry shellac and 15 g of beeswax per half L of alcohol. I'm using 91% isopropyl alcohol from a local pharmacy. And this needs to be warmed gently on an electric hot plate to dissolve the shellac flakes and melt the wax. But caution is needed because alcohol is very flammable, especially when hot. You cannot use a gas burner for this or the flames will cause the alcohol to catch on fire. You must use low heat on an electric burner outdoors and slowly stir the mixture until the wax and shellac have disappeared. Once done, the pot should be taken off the heat. And the trick is to continue stirring it as it cools down. The wax will not dissolve in the alcohol, but if stirred while cooling, it will form such tiny droplets that it may as well be dissolved. This is called an emulsion. The high concentration of the shellac helps the wax emulsion to remain stable because it thickens the alcohol and changes the density so that the wax neither sinks nor floats. The final paste wax is super easy to apply to any surface with a brush. The shellac soaks deep into the fibers of cardboard to provide excellent vapor protection while the wax mainly stays behind at the surface causing liquid water to bead off rather than sitting where it might soak in. This is also really easy to apply to fabric by either painting it on with a brush or by pouring some into a bag to mix into the fabric by hand. This does cause the fabric to become fairly stiff, but the durability and effectiveness of this coating to resist water is incredible. Most waterproof treatments, if pushed hard enough, will still let the fabric absorb water eventually, but this makes cotton behave as if it were solid plastic. It completely refuses to absorb water. I am so happy with this recipe. It's inexpensive, easy to apply, non-toxic, biodegradable, and very effective at repelling water. Look, remember this stool is made out of only paper and cardboard, and it is completely impervious to water. Try this. Build something out of cardboard for yourself and waterproof it. I think you'll be surprised at how durable it is. Now, one question that still needs answering about this waterproofing layer is the long-term UV resistance when it's exposed to sunlight outdoors. But we'll come back to that after looking at my second waterproofing recipe. To remove your personal information from the internet, you really need someone to step in on your behalf, like Delete Me, my sponsor for this video. There are companies out there called data brokers who basically make money by collecting your private information and selling it to scammers, telemarketers, and anyone else that wants to know more about you. Legally, data brokers have to stop selling your information if you ask them to. But there are thousands of them, and you might spend 20 minutes on each site figuring out how to submit a takedown request. Delete Me scans the internet for you, digging up data brokers that have your information and submitting takedowns on your behalf. This list is just some of the sites they submitted takedowns for in the first few weeks that I used them. If you'd like to make it a lot harder on telemarketers, scammers, and identity thieves to get your information and that of those you care about, check out Delete Me. You can get a 20% discount on a US consumer plan by using my link jointme. comighthawk and using the code nighthawk on checkout. I've been working on a side project which uses heatsealable waterproof fabric. This is basically just a normal fabric that has been coated on one side with thermoplastic. By using an iron, you can melt this plastic layer together between two sheets to form an airtight seal. Ever since I discovered this fabric, I've wondered if it might be possible to apply this sort of plastic coating at home. And so that's the question which led to the development of my second cardboard waterproofing recipe. This is basically hot glue, which I've modified to melt at a lower temperature so that it's easier to apply without burning yourself. This does have one advantage over the previous recipe because it does not use a solvent like alcohol, which is wasted as soon as it evaporates. For this, we just apply heat and spread the coating onto the surface. It can be easily melted again to stick sheets together or to repair cracks or tears in the coating. So, this recipe starts with several hot glue sticks and paraffin wax. One of the things I learned as I tried many different types of plastic to make waterproof coatings is that hot glue, which is more accurately called ethylene vinyl acetate

or EVA, is sort of like the soap of plastics. Lots of different plastics are incompatible with each other. They just won't mix, like oil and water. But add a little soap and it works. Hot glue can mix with just about any type of plastic, wax, or oil, and even allow other incompatible types of plastic to mix with each other. It mixes very well with paraffin wax. And for this recipe, for every 100 g of glue, I add 25 g of paraffin and 20 ml of mineral oil. This lowers the melting point of the glue to about 130 F, which is hot, but not blisteringly so. Now, you can also purchase low temperature hot glue, which can be used right off the shelf for this sort of waterproof treatment, but it's harder to find this in bulk and is typically more expensive. This mixture is best applied with a putty knife, or in my case, a scrap piece of plastic cut from the lid of an old storage bin. I like to lay this on fairly thick at first to hit all the bare spots and then reheat the coating to scrape off the excess. You only need a very thin layer for it to be completely waterproof and surprisingly durable. Even if you fold the cardboard multiple times, it still holds water and damage is easy to repair with a little heat. Sadly, this coating is not biodegradable. But in my case, I don't actually throw away or compost the majority of my cardboard. It actually heats my barn. Hot glue doesn't contain any of the chemicals that make many plastics harmful to burn, like chlorine or florine. And so when it's time to dispose of this cardboard, I can simply use it as fuel. This recipe can also be used as a fabric treatment, which is applied in the same way as wax treatments. It's melted into the fabric with a hot iron. In this case, you just want to make sure to unfold the fabric before it cools or it will glue itself together. With this recipe, you can not only make cardboard and fabric waterproof, but also airtight if you apply enough of it to make a solid layer. Just like the earlier recipe with shellac for long-term outdoor use, we'll need to think about UV resistant additives. Now, you can take the easy way out for this hot glue and paraffin coating. You can just purchase an anti-UV additive online sold for candle making. Sadly, I don't think those candlemaking additives will work with shellac. And even if they do, the ingredients are kind of a mystery and unlikely to be biodegradable. The easiest UVresistant additive that will work in both recipes is lamp black. This is the pigment which is used to make tires black. And you can purchase samples online or make it yourself by burning a vegetable oil candle under a metal tray. This is extremely effective at protecting coatings from UV damage, but unfortunately it also changes their color to dark black and so they get much warmer in sunlight. Titanium dioxide also works and changes the color to white instead of black, but mineral pigments like this can be difficult to blend and will leave lumps in the coating unless you have professional paint making skills. The UV additive I've been experimenting with recently for waterproof coatings is a metal sterate. Steric acid is a naturally water repellent fatty acid which can be joined with various metals like calcium, aluminum or zinc to form metal sterates. These are extremely water repellent and mix easily into either of our waterproofing recipes. The metal sterates themselves are mildly UVresistant as is, but as they slowly break down in sunlight, they form even more resistant metal oxides like the titanium dioxide pigment which is in paint, but without the need for difficult mixing procedures. Because these pigments form right in the coating at a microscopic scale, I recommend adding 1 or 2% by weight of a metal sterate to both of our waterproofing recipes for UV resistance. Aluminum, zinc, calcium, or magnesium sterates are all fine to use, and you can occasionally find these chemicals for sale online. Alternately, you can make them from very cheap and common chemicals. Starting with 20 g of steric acid and 3 g of lie, that is sodium hydroxide added to 100 ml of water and heated with stirring until the solution goes clear. Depending on what metal sterate you intend to make, dissolve one of the following onscreen quantities of ingredients into 50 ml of water and then pour it into the steric acid and lie solution. I find that calcium is the easiest metal sterate to make because it forms a waxy solid that gathers itself together into large flakes as opposed to the other metals which form super fine powders that can be difficult to filter and collect. Once the metal sterate is dry, it's ready for our waterproofing

mixtures. It should melt and combine just like the rest of the ingredients in both the shellac and hot glue recipes. Here are the final measurements for both mixtures. And that covers most of my current cardboard waterproofing knowledge. So, let's put this to the test by adding some new shingles to the camper. First, I'll have to remove the old roof panel and add some ribs for extra support for the cardboard. The tiles are applied to the roof starting from the bottom, overlapping them so that water doesn't find its way in between. To hold the shingles on, I used extra- wide plastic capped nails. If I used the hot glue coating to waterproof these, one advantage is that I could melt each layer of tiles to the next one, which would be extremely secure, but I think I'll stick with shellac for this test. Now, you might be wondering why I am putting a cardboard roof on my camper. Is it just a gimmick for the video? No. I not only want to test if cardboard will stand up to the elements, especially with my waterproof coatings, but I also want to test this for a completely different project that we have been working on for several years. Radiative sky cooling coatings. These coatings are basically magic. They can become colder than the air around them by sending their heat directly into outer space by infrared radiation. It sounds impossible. It sounds like it violates the laws of physics. It doesn't. Check out my radiative cooling playlist where I explain this process in detail. There's scientific papers all over the place that have demonstrated the effect. And we ourselves have made coatings that can become several degrees colder than air temperature simply by facing a clear sky. Now, if cardboard stands up to the elements, as I hope it will on this roof, it would make an excellent substrate for extremely cheap, basically free radiative cooling panels. Because cardboard already has internal corrugation, we could use the corrugation to pass air through those channels in this material, allowing it to become colder once it reaches the other side. But first, I need to know that this material can withstand the elements for a significant amount of time, long enough to make it worthwhile to apply a radiative cooling coating to one side, have it face the sky, and chill down some air so we can cool our living space, cool my workshop, cool this very camper. This is a long-term project that I've been going at for quite a while now, and I hope you all are as excited as I am to see the results of this test and find out if we can make radiative cooling not only accessible, but basically free. That would be awesome. So, now to hold the shingles together, I'll apply a coat of wheat paste, which will also harden the surface before adding the waterproofing. I think I've made a mistake. In order to properly test this roof, I thought that it would be important to remove the plywood panel underneath. Otherwise, how would I know if it was leaking? The problem is applying the wheat paste causes the cardboard to temporarily go soft. And with nothing behind it, it's sagging in between the wooden ribs, and I can't apply very much clamping pressure to hold the flaps down with nothing to support the wet cardboard from the back. I think that this is not the way to make a cardboard roof. If I were smarter, I would have joined all my sheets together into one seamless piece before tacking it onto the roof, but I just had to make it look like shingles. Well, now we get a chance to see some of the difficulty in working with cardboard. You have to think more carefully at the outset of your project about how it's going to behave than I did in this case. Well, this turned out a lot better than I thought it would. Uh, as the wheat paste dried, the cardboard tightened back up. And this surface is hard. I could probably stand on this without hurting it. The one area that needs a little bit more work is this front shingle, which lifted up as the wheat paste dried, and I didn't hold it down properly because I really wanted the nails to be high enough up to be covered by the shingle above it. That didn't really work out to make this front shingle lay as it should. So, I'm going to add a few extra nails along the front edge here. And I'll just cover those with an extra little piece of card paper and wheat paste, which will soak up the waterproofing later and keep this shingle held tight. Not every shingle is glued perfectly to the one below it because I didn't set a weight on all of them. But I think with the shellac coating, it creeps into the cardboard enough that as far as I can reach the brush into the gaps is about as far as water will go anyway. It's really good at causing the water to bead up so that it doesn't creep through small holes and imperfections. Obviously, time will be the real test for this, but the shellac coating only takes a few hours to dry, so we may as

well start by doing a quick test with the hose. Well, I made a little bit of a mistake here. Another one. I let this sit outside overnight. The first night after I applied the shellac, and it turns out that when you apply a really thick layer, it can take about 12 hours to cure. It was not fully cured by the time the sun set and the dew settled. And so, the uh unccured shellac actually got quite a lot of water on it. This water soaked in anywhere where there was still alcohol in the coating. Alcohol is very hyroscopic. It sucks water into it and so it pulled water into the coating. I ended up with a bunch of water stains on the shingles. And in addition to this, wherever it absorbed water, it's now been a few days since I applied this coating and those water spots are still a little bit damp. So, I really messed this up. Either way, we're going to still test this because if this will still repel water, if this roof is somehow still waterproof with all of the failures that I've had in making it, well, that really says something about how effective the coating is. So, we will test this. I'll get the hose set up, see if there's any leaks. It looks pretty good so far. It's definitely wet. All right, let's go uh let's go inside the camper and see what we can see. Look at this. Perfectly dry. I thought we would see a wet spot. I thought that I maybe would have applied the coating badly enough that we would see some kind of obvious damp spot forming. But man, it looks pretty good. That is awesome. That's so good. Let's see what it looks like. Let me I'm going to turn the water off so that I don't get soaked myself as I take a closer look at this. There's some issues right there. That's a patch that on that first night water, all that dew, the heavy dew rolled off of this uh ridge cap here and really soaked into the cardboard on those sections. So, that's an issue that occurred because I did not allow that first coating of shellac to fully dry before it got exposed to water. Boy, everything else looks pretty good. All right, what we're going to do is we're going to leave the hose running and uh we'll see if we're still leak free. Oh, I am so happy with that. We'll have to see what this looks like in a few months after some real storm exposure. And after about 15 minutes of water exposure, no spots of moisture on the inside. I think we are pretty safe in saying that this roof is for the present waterproof. We're going to have to expose it to some actual genuine stormy weather and some long-term water exposure to really see uh how long this will last me. But for now, that's a pretty good test. So, the camper roof somehow turned out to be both more difficult to figure out than I expected. I made several mistakes in its construction, but it's also much sturdier than I thought it would be. For now, it's watertight, and we'll check in on this again in the future. In the meantime, try using cardboard for new things. This was my first ever attempt at trying cardboard furniture, and it easily holds my weight. It's not difficult, and the total cost of entry to try my hand at cardboard furniture was what, a dollar in wheat paste at most? Another dollar or two maybe to make it waterproof. Should I also leave this stool outside and see how long it lasts? You tell me. All right. Thank you everyone for watching. I'll see you next time.