Well, I'm pretty new at this, but usually when i tie patterns that i need to sink (and retain a sleek figure) i use ultra-wire (I think that's the name). Because the UW is thin, it might take two layers to make it heavy enough for certain patterns, but it still stays thin. But now that i think about it, it seems like a waste of wire
Or you can use adhesive lead. I've seen that in a couple patterns, but I'm not sure how available it is.
Hope I've been of some help.