09 Dec How to build a milk bottle igloo
Build an amazing igloo made of milk bottles? Schools, nurseries, community groups and other children’s play centres want to add some Christmas magic by building their own igloo from recycled milk bottles and creating wonderful play opportunities for children. We’ve built several ourselves with each one being just that little bit stronger, neater or bigger than the last. With our experience and knowledge, you are sure to save time, have a great result and enjoy doing it!
Traditionally associated with people of Greenland and Northern Canada, an igloo can allow inside temperatures to be above 0°C whilst it’s -40°C outside. In a play venue, the igloo brings a sense of adventure, with opportunity to role play ice explorer, arctic hunter or marshmallow toasting champion!
Let’s get straight to it!
Preparation is really important, so we’ve written a dedicated section towards the bottom of the blog all about the things you need to do in your preparation stage. But for the fun bit, carry on reading….
- You will need lots of milk bottles. 400 were used to build the igloo shown in this blog. You need to prepare them in a certain way (see the preparation paragraph for a really important step though – Only once the lids are glued do you have strong building blocks to work with)!
- Start gluing together the bottles. (For tips on which glue to use see the preparation part of the blog later on!) Milk bottles don’t have much strength and they don’t like to be flexed around, so there are 3 construction techniques to consider.
- Build in a circle – this is quite tricky with British milk bottles as they tend to be rectangular. In the US, the different shape and larger gallon jugs can make this easier and if you have seen a circular igloo it’s probably in the US!
- Build against 2 or 3 walls – this is our favourite way – use the structures around you to give the igloo support. A room corner is much easier than the middle of a room.
- Build in a square and reinforce the corners thoroughly before the kids start playing in it. You may also which to use a sheet of wood as a floor so that the first layer of bottles can be stuck to it giving strong ‘foundations’
- Whichever shape you do, there are 2 build stages……The areas you want to look pretty (that’s often the front) and the areas you need to be strong (that’s kind of everywhere else). Start building the pretty areas first. At the start, you will only have a few bottles stuck together and will be able to get everything lined up beautifully in position, start glueing, turn it over, glue some more etc. So focus on the pretty part and make it as perfectly shaped as possible before it gets too bulky to handle. You can do this for about 40 bottles before it starts to get a pain to handle.
- Now move on to the rest of the structure. You want to try to lay the bottles up in the same basic direction (ie handles up or down, lids pointing in or to the back) partly for good looks and partly for strength. For strength, you want as much contact area between the bottles as possible and ideally to have 1 bottle glued to at least 2 others. This is where using a staggered brick wall (aka block wall) type arrangement really helps. If you look at any building with a brick/block wall you will see that at the end of a row of bricks of often a brick cut in half or rotated 90 degrees so it slots together with another wall. Try to avoid cutting a bottle in half as it loses all its strength –we find it better to extend a bottles length to 1.5 times its original length by gluing on an extra section (see the pictures).
- The roof is one of the hardest parts to get right. The flexible nature of milk bottles means roofs often droop under their own weight. Try to build a roof in the same shape as a classic ‘Humpback bridge’ so that as the roof droops under it’s weight, it will squeeze the bottles together tighter and make it stronger. If you build a flat slab roof, the droop will be trying to pull the bottles apart and be weaker. The good news is that a classic igloo domed roof uses exactly this technique to be strong. Also, the closer the walls are together the more support is available for the roof and the less it will feel like the roof is pushing the walls apart. This is also where building next to a solid wall helps give your igloo support.
- How much glue to use? Ideally, you want glue everywhere…..but glue is expensive and it needs removing when you choose to recycle the bottles afterwards. We find either dots of glue or a single strip of glue to be good enough and are easier for you to remove when the igloo is sent for recycling.
The Safety part
- Think about whether your design is right for where you are using it, who is using it and how they will use it. Our designs are used by children who are supervised, but we still build it in a way that prevents for children from climb on top, it’s got super comfy flooring to sit on, well secured to walls, away from any sources of heat, and its not at risk of being blown away by the wind…. Consider if there are any hazards in how it might be used, and how you can prevent them.
- Lids should always be glued on and checked to ensure there are no choking hazards. If you cut any bottles, prevent the sharp edges being exposed or sand the edges to soften them. Ultimately, you have to take responsibility for what you make and how you do it.
- Protect yourself. Whatever type of glue you use, you need to protect your hands with gloves, and at times you might need eye protection (and respiratory protection if using a solvent-based adhesive). Knees can take quite a knock so consider knee pads.
Plan, test, adjust We spend most of the year collecting milk bottles and we recommend choosing bottles with glueless labels – this is where the label is in the form of a film that can be removed with scissors and this has no glue residue leftover.
Make sure the bottles are spotlessly clean. Hop soapy water is needed to remove any milk proteins residues and leave the bottle to dry upside down for 24 hrs to ensure it completely dry before you put it in storage.
Milk bottles are normally made of HDPE (High Density Polyethylene). It’s a fantastic material and easy to recycle (linky) but for igloo makers, it has one problem…it is harder to stick than Teflon! Not everyone can afford a laser welder so you may have to do with old fashioned glue. But HDPE molecules don’t like to adhere to other substances and most glues just don’t work well. We’ve tried lots, and we tend to use an industrial polypropylene adhesive, but we also know some people use Epoxy glue, or Superglue with a primer designed for troublesome plastics. We’ve also heard that some people like to use sandpaper to roughen the surface a little or a blowtorch to soften the surface! Suffice to say that you shouldn’t just expect to buy a glue gun from your local craft store and expect it to work straight away. What you use will depend upon what’s available in your region, and your price range. We strongly recommend taking a few milk bottles and trying out the different glues available and different techniques. It’s normally best to do this in a warm room as most adhesives work better when applied hot…..remember to wear suitable safety equipment! When it’s set, give the bottles a good bashing; a glue can sometimes be great when pulled but when shock loaded or twisted it can fail catastrophically. Once you find the best adhesive, practice using it and work out how much you need.
Can you use water bottles? If you make it out of water bottles, the principles are the same but the plastic called PET which may need a different glue type than water bottles.
Stock up on bottles! You will always need more bottles that you have! We use 400+ when we build an igloo. Its best to have mostly bottles of the same shape in order to get the best visual effect.
We love recycling, and at Tots Town we recycle about 75% of the waste we produce. It’s fantastic to re-use the milk jugs for an igloo but let’s make sure you can recycle them afterwards. All that glue needs to be prevented from entering the recycling chain. First, destroy your igloo! Try dropping bottles on a hard surface – the shock waves from impact are often strong enough to separate glued bottles. For any that survive the drop, try peeling them apart from one end. Once you have individual bottles, you need to remove the glued-on lid (or chop it off) and then removing the glue on the sides of the bottle. If the glue doesn’t just peel off, then use scissors to cut out the area with glue on. This is where you will thank yourself if you used dots or lines of glue rather than spreading it everywhere. With careful construction, you should be able to recycle over 80% of each bottle.
So, now you know how we do it, it’s time to try it yourself. Do send us pictures of you building your own igloo!