I am pressing some seams open to reduce bulk. I am making Ohio star blocks so on the hourglass block I am pressing to the dark side the first HST but when combining the second HST to make the hourglass I am pressing that final seam open. That is where I am seeing the light thread. I have a medium grey Aurifil spool but it isn't much darker than my cream so I don't think that will help much. I will look for a darker grey Aurifil to use for my mixed blocks.