Home DIY

I don't have any flax but have some hemp cord, could I use that to stuff the bigger gaps, then mix some sharp sand into the putty to seal?

I would think that sharp sand is too coarse, and that the lack of oven heating would have an impact on it's ability to make a good putty with the oil.

I'm not going to get hold of half a cup of lime

You can buy small volumes of premix NHL here