Wrapping a Fire Piston cotton string gasket can be a tricky process until you get the feel of how tight (or loose) you need to make it.  Typically it takes several attempts until you get it so that it still fits into the piston bore but still is holds the compression when the piston is pushed down so that the pistons "rebounds" a little at the bottom of the stroke (indicating that there was a lot of pressure in the cylinder.)  The more pressure inside the cylinder, the easier the tinder will ignite... and to get more pressure you need a gasket that will hold in as much of the air as possible in the cylinder as you hit the piston down into the cylinder.

Here are a few tips that might solve you gasket wrapping problems...

First let me go over compressing the gasket once you wrapped it according to the instructions included with the Fire Piston:

Grasp the piston plunger by the handle in your left hand and place the plunger on a kitchen counter or table top such that the handle over hangs the edge and the shaft lays flat on the surface. Lay a metal ruler, narrow wooden board, flat side of a wide knife blade, ( anything wider than the gasket, rigid and flat will do ) on top of the gasket, press down and roll the shaft between the two flat surfaces. The harder you press down, the smaller the gasket diameter becomes.

If it squeaks as you insert the piston into the cylinder, its a little too tight in the bore and the string gasket needs just a bit more rolling to compress the diameter. You can use any smooth, hard item as a "roller" to push down on the wraps to compress them further. Use increasing amounts of pressure on the roller until the piston travels smoothly yet still has full contact with the cylinder walls.
Don't over-do the amount of rolling force as this can result in a gasket diameter that is too small and wont seal. Go slow - roll, fit and feel + repeat as necessary.

Initially, the string needs to be really "gobbed up" with Vaseline and worked up and several times to force the grease into the fibers. I actually dip the shaft into the jar of grease. As compression increases the air will find escape pathways and the grease will be forced into these. This is important and probably the number one reason for difficulty with Fire Piston kits.

The most significant tips are as follows:

- Maintain tension on the string while wrapping. I usually pull the string tight every couple of wraps. This helps in keeping the fibers close together and compressed against each other.

- Roll the completed gasket to eliminate lumps and bumps

- Grease it excessively at first to seal the fibers, then wipe off the excess. Make sure there is no grease left at the bottom of the bore as this will inhibit ignition. Charcloth left at the bottom will also prevent ignition.

You may have to try wrapping the gasket several times until you get it right but in the end it will be well worth it as you amaze your friends with this amazing fire making device.