CTE 3763 Exam 2 Study Guide Seams Edge Treatments Seam line the stitched line if a seam parallel to and always a speci c distance from the raw edge of the fabric important for grain t allowance Seam allowance the narrow width of fabric between the seam line and the cut edge of the fabric lowers cost if smaller 5 8 of an inch Seam types fabrication functional aesthetic depends on seam location arm seam line gets more stress intended use of garment styling equipment used In uences appearance durability comfort ease of alteration ASTM International total uniformity rigid scienti c 6 seam classes 4 major Superimposed Lapped Bound Flat Seam speci cations very important because we are a very global world Speci cations use two uppercase letters that identify seam class followed by a lowercase letter or letters that identify seam type Superimposed seams SS also known as plain seam Most used seam class The cut edges of the fabric layers are stacked on top of one another to form a booked seam ready for stitching When found on inside of garment usually pressed open at busted or butter ied Lapped seams LS Has the most variations NOT most widely used Formed by overlapping the seam allowances of two or more plies of fabric and sewing them together Specialized jeans men s dress shirts leather Flat fell seams more casual in appearance Ensuring the seam will lay right Can only be used on straight edge Bound seams BS Made by encasing the raw edges of seam with fabric strips With increased use of safety stitches or serging and the growing use of knit fabrics that do not ravel the use of bound seams has decreased Binding the edges very aesthetic Use on raw edges often necklines details Not used on structural seams used on edges Flat seams FS also known as butt or exposed seams Join fabric plies by butting the raw edges together and securing them with a 600 class cover stitch or a zig zag stitch Look same on both sides No seam allowances economical Very inexpensive less fabric used Less bulky exposed seams Almost never used on wovens Advantage of using with knits they curl avoid bulky seams Ornamental stitching OS Can be just a top stitch fully decorative added to seam Can be functional keep garment at while creating a decorative top stitch Dressmaker details Edge Finish Stitching EF Stitch seam and nish edge at the same time Economical saves time fabric Explosion of knits no seam allowance Stitches applied to nish an edge or for ornamental purpose Prevent raveling of woven fabrics Keep the edges of lightweight to medium weight knit fabrics from curling OS and EF technically don t join fabric together French seam a seam within a seam high end couture seam quality indicator inner beauty ex sheer top Seam Performance seam strength is affected by type and width of seam strength and tendency of the fabric to ravel characteristic of stitches depends on hot it is stitched pressed and nished t fabric care of garment Seam quality defects Unraveling caused by a broken or skipped stitch Restitched seams re ecting a splice where a thread broke or ran out during construction A ropy hem caused by poor operator handling or too much pressure on the presser foot Finish should not add bulk to a seam a variety of nishes are used in the industry Plain Finish when a plain seam is left untreated garments that will be fully lined Clean Finish turned over the seam allowance and stitched neatly nish edges inside the garment raw edge of seam or hem allowance folded under once and stitched add bulk Pinked Finish edge cut with a sawtooth blade generally only opaque fabrics are pinked because serrations show through sheer fabrics inexpensive non bulky edge nish Bound Finish covering the raw edges of each ply with a folded ribbon tape or bias binding Overcast Finish a series of loose slanting hand stitches placed to encircle the saw edge of each seam allowance Bias seam forms horizontal softness most often in skirts Edge Finishes methods other than hems include Facings Cut on facings Bias strip 1 Shaped or Separate Facing Fabric pieces shaped identically to the garment edges they face Should be cut on the same grain as the garment piece they face Ideal for shaped necklines hems sleeveless armholes as they conform to Shaped facings are sewn on not folded back Require less fabric than extended facings because separate pieces are laid out any shape to better advantage 2 Extended Facing Simplest type of facing Require least labor add the least bulk to garment Used less than shaped facing due to more fabric usage Can only be used on straight edges 3 Bias Facing Narrow bias strips of fabric used to face raw edges Form a neat inconspicuous facing approx 1 2 wide Require little fabric Most cost efficient Useful for sheer fabrics Low in bulk Not suited for intricately shaped edges Seam Quality Defects Restitched Seams Broken Stitches Where a splice occurs on the stitch line If this occurs on Topstitching then the seam does not appear to be 1st quality merchandise Caused by 1 thread breaks or thread run out during sewing or 2 cut or broken stitches during a subsequent treatment of the nished product i e stone washing How to minimize use a better quality sewing thread proper machine maintenance correct material handling techniques Skipped Stitches Where the stitch length is inconsistent possibly appearing as double the normal stitch length or where you can see that the threads in the stitch are not properly connected together Caused by the stitch forming device in the sewing machine missing the thread loop during stitch formation causing a defective stitch On looper type stitches this will allow the stitch to unravel causing seam failure How to minimize same as above Open Seam Seam Failure Stitch Where the threads in the seam have ruptured leaving a hole in the stitch line Caused by 1 Improper stitch for application 2 Inadequate thread strength for seam 3 Not enough stitches per inch Minimize better quality thread proper size thread check for stitch cracking in knits Open Seam Seam Failure Fabric Where the stitch line is still intact but the yarns in the fabric have ruptured Minimize reinforce stress points with bartacks make sure patterns have been designed for proper t ideal seam construction is used Seam Failure Seam Slippage Where the yarns in the fabric pull out of the seam from the edge This often occurs on fabrics constructed of continuous lament yarns that are very smooth and have a slick surface Also caused by loosely
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