What kind of cob/daub mixture for a dollhouse-size wattle and daub house?

The class I'm teaching has started their wattle and daub houses. To get the uprights attached to the cardboard, I used paper clay, since it was an affordable and strong foundation.

Some of the kids' houses. Some are making Celtic roundhouses, and others are making rectangular cottages

New week we'll be wattling it, weaving the walls with basket making round reed. Since the sticks are so close together--and I don't have enough skinny, long willow/hazel--this seemed like a good option for the walls.

I'm wondering what to use for the daub, especially on such a small scale. I'm thinking that instead of making cob with straw, it might be better to use something with a finer texture, more like a plaster?

I have access to pottery clay--both with and without "grog." Grog is "used in pottery and sculpture to add a gritty, rustic texture called "tooth"; it reduces shrinkage and aids even drying. This prevents defects such as cracking, crows feet patterning, and lamination" (grog is usually made up of ground up pottery shards). I'm thinking I should use the grog clay?

I have play sand, but I'm thinking I should purchase some sort of sharp sand? If the daub is thinner, maybe I should go with just clay and fiber? The soil around my house is gravely loam, with a high sand content, so maybe I should sift that and use it in place of sand?

What would be the best fiber? I could try to shred the straw so it's thinner. I have a bundle of raw nettle fiber that we could use, too (though maybe I should save that for when we make paper later in the year?). I also have a bunch of wool, but I know wool isn't nearly as rigid as nettle or straw. Whatever I use, I'll need a lot of it, because there's 30+ students.

I've been making an "example" wattle and daub house, mostly so I can learn the techniques. I messed up my own daub. I didn't have enough sculpture-grade clay, and so used the kaolin clay I spray on my fruit trees to prevent apple maggots. But, the grain size is very small, and so it doesn't hold well together. I used play sand, since that's what I have on hand, and used my own hair for fiber (pretty sure the kids won't want that!). It turned out well enough that the kids and other parents are impressed by it, but it's rather crumbly and bumpy!

My wattle and daub house. The daub/cob is rather lacking!

I would love any and all advice!

First off, that is an adorable project to be starting with children . Well done on your innovative teaching method. I am a basketry nut x5y and I’ve been cobbing for 2y. Imagine how exciting it is to answer questions about a technique that combines two in one!

Second off I’d like to answer your question. As I was reading your post I instantly thought of natural hemp fibers. But then you mentioned nettle so you and I are thinking similarly about fine fibers for a tiny project. In order to scale it, nettle wouldn’t really be easy to source though. my idea for you is to cut up twine. Bonus if it’s hemp twine. You might get an aesthetic that is more pleasing with your paper clay if you were to use natural cotton and you can get a massive role of it if you buy cast padding. Another additive could be loose tinsel. I thought kids could like that. Or maybe even like friendship bracelet pieces, I don’t know I’m just trying to think outside the box for you . Anyways, good luck and I sure sure would love to see what you come up with.

Thank you! I wash thinking that maybe unraveling some twine and using that for the fibre for the would be the answer.

Do you think I should buy sharp sand, or would my sandy dirt work well enough if mixed with high quality pottery clay?

I use dried grass clippings to make cob for building kilns. Its durability is irrelevant there as it burns out, and dollhouse sized houses will not be tested for weathering or longevity either. It adds considerable wet stiffness and will keep dried walls from cracking apart.

I figured I should give an update, since their houses are now finished (I don't have a picture yet of the houses with their thatched roofs, but the thatching kind of blocks the daub, anyway).

What we went with was about 2/5th "all-purpose sand" 2/5th pottery clay (with grog) and 1/5th ripped up jute twine.

Since the school has a pottery class, and clay tends to get hard after a while, I used all the funky bits of dry clay, soaked in water. I added one scoop of that, and then one scoop of all purpose sand, and then a handful of ripped up twine. I cut the twine into 3 inch pieces, and then unraveled those pieces. This made a nice fine fibre. Sometimes I carded or brushed out the twine pieces to be even finer. That was even better, but a lot more work!

The mixture worked well! Some kids didn't mix their daub very well, and had a few cracks. Sometimes there were big clumps of twine because they didn't fully mix it, But, even still the houses are surprisingly stable!

After their daub dried, I mixed up lime milk paint with red ochre, yellow ochre, green earth, charcoal, and calcium carbonate. I showed them depictions of celtic roundhouses and Anglo-Saxon wall paintings, and let the go for it. The paint sealed the cracks nicely, and the houses look quite nice.

(If anyone is wondering what we used for the wattle, we settled on round reed used for basketry). This made it a lot easier for the kids to weave their walls, and was a lot easier to source for 30 kids than trying to get that much willow, vines, or skinny hazel. At this small of the scale, the round reed was perfect!

That's awesome.