I cannot do without gridding, even on the linen of 32 count. The best tool is a water-soluble ink pen (the one you get on Ali Express), they leave a very fine line and disappear completely upon soaking your completed project in a luke warm water for 30+ min.
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I have found that I can grid for full coverage using waxed hand quilting thread. Not quite as easy to remove as sulky sliver (frankly, I remove as I go), but much more widely available where I am.
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