Here's how I'd pack a 18" chute in a shorter BT-60 sized model.
Sometimes a packed chute can't be long and narrow. On a squatty model you won't have room for wadding, parachute and the nose cone shoulder.
You still want the parachute to eject like a piston without any "blow-by" of the ejection charge.
As mentioned earlier, always open and air out your parachutes right before launch. Sprinkle some talcum powder on the chute before packing so it won't stick together.
TIP: NEVER use talcum powder with corn starch! Corn starch is flammable.
After spiking the chute, fold into thirds. The parachute will pack shorter.
Fold the three-fold pack in half vertically, then in half again.
Wrap the shroud lines as shown in the previous post. Don't wrap the lines tightly.
TIP: As extra insurance to prevent any hot spot melts -
Cut a piece of sheet wadding down to about 3 1/2" square. Set the low end of the packed chute in the center of the square. Wrap the low end of the parachute with the wadding. Wrap the sides of the wadding up the chute.
It is important to cut the wadding square smaller. You want the wadding sheet to peel away from the parachute at ejection.