Make, learn and talk about needle lace.
I don't think it matters about the kind of foam for teneriffe. Just choose something that is comfortable to hold and to work on. I would choose a thin piece 1 inch thick rather than something 2 inches thick. I also think Barbara's idea of using round plastic canvas as a base is a good one. I've worked a few really simple practice pieces that way. There are ways of using a foam base and setting pins around the perimeter to wrap the spokes around, but I found that my thread kept getting caught up on the wrong pins, and it drove me nuts.
I wanted to try foam because then I can work in any shape, also it's easier for me to buy.
Plastic canvas does come in rectangular pieces and in octagons -- both shapes often used in sol laces. But I don't think the substance of your backing material is crucial. Do what works and what you can find locally. I look forward to seeing your efforts.
The problem I don't know how to solve is: what to do to secure the ends of the thread used to make the spokes. Do I assume that the wrong side is what faces me and I can just make knots on the back? Is there a correct knot or a "best kind of knot" to use?
And what do I do to start a thread for doing the rounds of weaving or coral knot or whatever? What is the best way to secure the ends of these embroidery threads?
I use two pieces of strong card covered with thin batting & fabric as a base, and the pins go in between around the side. I push the pins right in so there is less catching. I can make my base to whatever shape & size I like, but so far have only done circles. The plastic canvas idea looks good but I think that would have limits.
I did my first pieces on a base of two layers of calico stretched in a hoop & found I could not get the support I wanted. Even though the hoop screw was as tight as I could get, the fabric kept slipping & my lace ended up warped.
Lorelei, after I finish winding the spokes, I leave a very long tail which I then use to start my weaving. To end, I take the needle down through the middle of the weaving for a distance, then cut the remainder of the thread back very close. A trick I was taught doing needle-weaving on drawn thread channels.
I am not sure if what I am doing is correct, but it works for me.
Your description of two pieces of cardboard brings to mind another possibility: foam core. It is sold in artist supply stores and is 2 layers of cardboard with a thin layer of foam between them. That would be a perfect place to stick the pins so they would lie along the plane of the cardboard survace, but the heads could be pushed in all the way to reduce catching. I haven't tried it, but I think I will.
But I'm still not clear about ending threads. Are you saying that you start with an enormously long thread, long enough to make all the spokes and all the weaving and embroidery? And when you say take the needle down through the middle are you counting on friction alone to prevent the whole thing unravelling?
Lorelei, I have thought of foam core before though I have not tried it. I wondered how stable the core would remain & whether it could be reused.
I have a center hole in my base, then thread the end of the thread through the hole & secure well at the back. This leaves the whole ball, skein, reel etc of thread at the front to wind around the spokes. From there I leave a very long length before cutting to work my patterns.
As for finishing, I guess it is friction that is holding the ends. I Have not had a problem yet of it coming undone, and if someone has a better way of ending I am more than willing to learn.
I think that the rack have to be suitable for the line that we will use. I used many types. The strong card covered also (1° photo). Today, in Renda sol (Sol Lace), looking for much quality in the final product and using fine line, we use the wood rack that is in the foreground in the photo. Only with it we can make more elaborate pieces.
All those photos are interesting. They are good ideas, and even simple cardboard is useable. The first one looks like what we call "corrugated" cardboard -- 2 layers, with a middle layer.