[pct-l] Sewing/ Introduction

[ronm@fallingwater.com (Ronald Moak)]

Joining two pieces of material together end to end is typically done with
either a Flat Felled or Lap Felled seams. Typically manufactures use a Lap
Felled seam. It has 2 rows of stitches visible on both sides of the seam vs.
1 for the Flat Felled seam. 

However on Silicone coated nylon Lap Felled seams are almost impossible to
do. Flat Felled are a little easier but can still come out messy. Especially
if you're covering a long seam. 

For projects like tarps were I'm only making one or two of them, I use a
different method of joining the two edges together.  See picture below.

1) Setup a fairly large area where you can lay the material out undisturbed
over night. A living room will generally do.
2) Either make some silicone waterproofing mixture ( 1 part GE Silicone II
clear caulk mixed with 2 parts mineral spirits mixed well) or get a tube of
McNutt Silicone sealer.
3) Lay a base of wax paper down under the seam. You don't want to glue your
material to the carpet.
4) Lay a bead of sealer on one edge of the material your going to sew. Make
sure you have enough for a 1/2 inch seam.
5) Lay the second piece of material over the first and apply pressure.
Making sure to squeeze out all the air bubbles.
6) Let the sealer cure for 12 hours.
7) Then sew two rows of stitches along the length of the seam 1/4 inch
apart.

The resulting join will be far stronger than either the Lap or Flat Felled
seam and be thoroughly waterproof to boot. The sealer will close around your
threads as you sew the seam. You may get a little residual sealer sticking
to the needle. Simply wipe it off. 

	--------------|---|--- 		<- Material
		0|00|0		<- Sealer
		--|---|-------------	<- Material

-Fallingwater