This is an easy way to quickly make any fabric airtight. As such, you can use this technique to make a wide array of inflatable objects.
Step 1: Go Get Stuff.
- liquid latex (get Clear #10)
- fabric (canvas is ideal since it is strong, tightly woven and doesn't stretch)
- a bar of Dove soap or similar ( bacon soap is tempting but not recommended)
- three plastic dishes (large enough to hold soap)
- baby powder
- 1 cheap paintbrush
- paper towels
Step 2: Prepare the Materials.
Get your three bowls. Fill one bowl halfway with water and stick your brush into it. Fill the second bowl with a small amount of liquid latex. In the third bowl stick a bar of soap.
Step 3: Paint Your First Coat.
Take the brush out of the water and rub it into the bar of soap. This is done to keep the latex from bonding to the brush's bristles, but remember not to leave too much soap on the brush. After rubbing the brush against the soap, rub the brush against the side of the bowl to get all the excess soapy water off the brush.
Now dip the bristles of the brush into the liquid latex about halfway. Rub off the extra latex on the side of the container so that it doesn't drip everywhere.
Quickly paint a thin horizontal layer of latex onto the canvas. By horizontal I mean that all brush strokes should be made horizontally across the surface of the canvas.
The first coat will take longer and use more latex than all subsequent coats.
Step 4: Paint the Second Coat.
After about twenty minutes the first coat should darken and be dry to the touch.
At this point you are going to want to lay down the second coat. This time make all your strokes vertically or, rather, in the opposite direction of your initial strokes.
After the second coat your fabric should be airtight.
Step 5: Paint Additional Coats.
Even though your fabric is now airtight you are going to want to put on at least one more coat for additional strength.
Just make sure you paint on the latex in alternating patterns. For instance, since your last coat was painted vertically, this new coat will be painted horizontally.
I wouldn't recommend putting on more than 5 coats of latex. After 5 coats I imagine that the fabric will start to get very weighted down.
Step 6: Powder It Up.
Once your fabric is well-coated in latex you are going to want to keep the latex from sticking to itself. This is easily done.
Take your container of baby powder and generously shake the baby powder onto the surface of the latex. Rub the baby powder vigorously around over the surface until the latex is no longer sticky.
Now you are done.