Now this is where the confusion comes in.  Because there is such a wide variety of materials being sew in many different weights and types, the actual finished seam may not always be perfectly butted together as the term Butt Seam implies.  Many times the left ply ends up being overlapped by the right ply by about ½ to 1 mm, Figure 2. For most operations where the same color of material is used for the left and right plies this slight overlapping is acceptable and actually ends up strengthening the seam.  However, for those customers who wish to sew two different colors of material, this can create a problem.  Given the slight overlap and the variations in type and weight of material being used, the seam appearance may not be acceptable. Often the meeting point of the materials is not in the exact seam center and can look uneven and wavy, therefore creating a poor looking seam on the finished product.  (This is not something new; it has been the case since the 36200 was introduced over 40 years ago.)  Most customers would either accept the seam as it was sewn, or have their technician modify the presser foot or presser foot shoes until the seam appearance was acceptable, or convert their machine to sew a lap seam.