Solar Dyeing - Part 1 Building a Solar Oven
Updated: Aug 14, 2020
My mission and my passion at Loch Ness Knitting is to share sustainable dye practices, so that we can make better and more informed choice in our craft projects.
Energy is consumed in every element of the textile process, from growing to processing, transporting and dyeing. If we can turn any part of this consumption to a renewable energy source then we begin to reduce the overall impact of our textiles process.
One of the ways that I do this in my own practise is to use renewable and passive sources whenever I can. I want to point out here that I'm not perfect, and my process is not finished yet. But every small improvement we make helps to contribute to the bigger picture, so please do not discount your individual efforts as too small or imperfect. They matter!!
Solar energy is something that is often ruled out for small business and projects as it requires a heft up front investment in technology, and in the UK many of the grants to support this have ended or become so complex that small makers simply can't navigate the system anymore. I would love to install solar panels on my studio and take my whole process off grid but I don't have the captial for this just yet.
This doesn't mean that I can't harvest solar energy for dyeing. I've gone for a low tech option of a solar oven. It's so easy to construct everyone should have a go!
Start by finding a flat area of outdoor space. The best spot is one that is South facing, this will capture the sunlight for the longest time during the day.
You don't have to dig up a pretty flower bed. My solar oven is located at the back of my shed and is a great project for keeping down weeds in this neglected part of the garden.
To build the oven I've got some old cardboard boxes, some old pallets and a roll of reflective insulator.
You only need a small amount of these items so check with friends to see if they have leftovers you can repurpose.
The first step is to flatten the cardboard boxes and places them under the base pallet.
This will cover the grounds and stop weeds from growing up underneath.
This will also help to provide a base level of insulation and prevent heat loss into the ground.
If you have ever been camping you'll know the importance of having a ground mat as a base level insulator.
The next step is to organise the pallets to know roughly what is going where.
I'm not going to fix the pallets together because I need to dismantle the oven during Winter.
It is very dark in the Scottish Highlands during Winter so the oven will not be used then. It could also be damaged by rain and high winds.
I may also have to relocate it in another area as I carry out other groundworks for my dream of building a purpose built studio.
Time to get the tools out!
I measured and fix the reflective insulating foil to each of the pallets.
The extra foil is easily trimmed using scissors. Don't dispose of these bits, they are useful for filling in small drafts in other parts of the house, shed or studio.
As I'll be moving the finished oven around I also took extra time to make sure there were no sharp nail ends sticking out after fixing.
All sides are now covered in the reflective insulating foil. You'll be able to tell straight away that the oven is capturing light and heat.
Note that the largest back panel, the one facing the direction of the sun, is deliberately placed at an upward leaning angle to catch the light.
The oven is not ready to start using.
I'll be reusing several plastic storage boxes with lids to hold dye materials, yarn and water (from my water butts).
To avoid using plastic you could also reuse old pans or slow cooker pots. Just make sure they have well fitting lids to avoid moisture loss during the evaporation cycle.
The solar oven can be used from May to September when the weather is warmest and the hours of daylight at the longest.
The temperature inside the oven is averaging about 7 degrees higher than outside the oven.
This means the materials cool off slowly overnight, and tend to stay warm.
To increase the heat inside the plastic boxes I've added another reflective surface by using foil trays in the base to hold the yarn and dye materials.
The solar oven is a great way to dye natural materials such as foliage, leaves and flowers which respond better to gentle heating when creating dyes. The gentle process of water evaporating during the day and dripping back overnight spreads the dye beautifully over the surface of the yarn.
It allows me to dye yarn in totally passive manner with a very low energy footprint.
This is an easy project to try at home and a great one to use with kids or groups where you want to avoid direct heat sources due to safety.
If you have a go at home please share your picture and dye results in the comments.