The simplest way to deal with this problem is to use an old trick from garment sewing -- "stay stitching". Decide on what part of the quilt you will leave open and approximately how long your opening for turning will be. Before you stitch your layers together, simply stitch 1/4" from the edge or your quilt using a standard length stitch. If you are using a wider seam allowance, place your stay-stitching at that seam allowance line. Stay-stitch both the top and backing in the area you will be leaving open for turning.
Stitch your layers as usual leaving the opening area where you stay-stitched. Be sure to trim your batting accurately. Marking the cutting line on the batting with a straight edge can help with trimming the batting evenly. After batting is trimmed, turn your quilt through the opening.
After your quilt layers are turned you will have the stitching line as a guide to turn under. Simply finger press the stitching line and match the stitching line on the quilt top to the stitching line on the quilt back. Hand stitch opening with the stay-stitched line just inside the quilt.
The stay-stitching will keep the top and backing fabric from stretching and will give you an exact line to fold the seam allowance under and hand stitch. Easy.
Pressing Pieced Blocks And Setting Blocks Together
Pressing pieced blocks
Many quilt books and patterns instruct you to "press to the dark". Sometimes that is not possible when there are too many seams coming together and there is too much bulk. The pressing to the dark "rule" is left over from our hand piecing quilting ancestors. When hand piecing templates were made the exact size of the finished patch and the seam allowance was added randomly or "eye-balled". Because of this the seam allowances were usually uneven and of different widths. Also all the stitching was done by hand -- sometimes with large stitches -- and the seams were weak. Pressing to one side -- usually to the dark -- was necessary to keep the strength of the quilt even after being hand quilted.
Now that we rotary cut our pieces and our seam allowances are a standard width, there is no reason to continue in this archaic pressing method. Also our lock-stitch sewing machines make a very firm and tight seam.
It is OK to press to the light if it is necessary to keep the build up of numerous intersecting seam allowances less bulky. If the dark color shows through slightly, you might want to trim a slight amount from the dark seam allowance allowing the light color seam allowance to cover the darker seam allowance.
A good rule to follow especially in strip piecing is to press in the direction stated in the pattern. Most pattern designers carefully plan pressing directions for ease of future assembling so you would want to follow their directions. That way when you are working on the next step you will have your seam allowances pressed in the direction required to continue the piecing process as the designer planned.
When piecing individual blocks and the block has a center area it is usually recommended to press seam allowances toward the outside although this is not an absolute rule. Also if several seams are intersecting from one direction and the other direction has fewer seams, press in the direction of the fewer seams.
At other times you might want to press seam allowances toward the piece you want to "come forward" or stand out. By pressing seam allowances toward these particular pieces they become prominent because the pieces surrounding them tend to recede.
Did you know it is OK to press seams open? Today's quilter has a lock-stitch sewing machine. Many quilters began sewing by making garments. We used to stitch the back seam of our trousers and press the seams open! Then we wore them for several years and sat on that seam and gained weight in those pants and still the seam didn't split open. All men's dress trousers have the back seam pressed open.
Many professional quilters press all their seams open. Machine quilting of our modern day quilts help stabilize the stitching of the piecing. Our machine made quilts are stronger than the hand made quilts of yesteryear.
The direction you press your seams is also determined by how you will be quilting. If you will be machine quilting "in the ditch" you will want to press seams away from where you want to quilt. This way you are quilting only through the three layers of the quilt "sandwich" rather than the additional layers of the seam allowance.
If you will be "outline" quilting (1/4" from seam) it really doesn't matter the direction of pressing for quilting purposes because you will not be quilting in the area where the seam allowance is.
If you find your seam allowances are "twisting" remember that once some of the seams in your block are pressed you will need to be careful to not turn them in the opposite direction when stitching a new seam.
Look at your block carefully and decide the direction you wish your seam allowances to be pressed rather than following any particular rule. As you become more experienced at piecing, pressing will become easier and you will know the direction to press each seam allowance.
Setting blocks together
If you are setting pieced blocks together with plain squares it is recommended to press the seams toward the plain squares. This will reduce the bulk of the pieced seam allowance area.
If you are setting a pieced block to a pieced block, you will need to choose which direction you should press. One of your blocks may have fewer intersections than another so you would press toward the block with less seam intersections.
When setting blocks together it is easy to get the seams going in opposite directions so when you press your quilt top you find the seam allowances are "twisting". There is nothing wrong with this. When this happens to me I simply press the seam down flat at one end and at the other end I allow the seam allowance to "twist" and press it very flat. Once the quilt is layered with batting and backing and quilted you can hardly tell that the seam allowance was "twisted".
If this "twisting" bothers you, simply place a pin in the opposite end of the seam allowance as you are stitching to keep that end of the seam allowance flat. When you are stitching the next row of blocks, the pin will automatically show you which way the seam allowance should go as it is already pinned down in the proper direction.
Pressing a quilt top is important and you should press as well as possible but don't obsess about it so much that it makes you not enjoy the quilting process.