probably another post that has been talked about over and over...... but do u use 90 degree Ct or 109 degree Ct for skimming. i currently use 109 degree 1.. are 90 degree 1s better ..... also dont know the name of 1 but it looks like a margin trowel with 2 small edges at 90 dergree... can any inform me what they are used for. cheers