Spray packing foam is a liquid polyurethane combination of two formulas that become a semi-hard foam when exposed to air. This type of foam is excellent for packaging odd-shaped or fragile objects for shipping because it conforms completely to the object and absorbs a great deal of shock. Spray packaging foam is very light, even after it has solidified, so shipping costs are not affected. Spray foam is available in kits, which make it easy to use at home.
Put on safety goggles and rubber gloves.
Put a heavy-duty plastic bag in the bottom of a cardboard shipping box. Spread the bag open so that it covers the entire bottom of the box and the top edge of the bag falls along the outside of the bag.
Put the spray kit together according to the package instructions. The kits are available at home improvement stores and are designed to be used without having to mix liquids yourself. Most kits will only require that you attach a nozzle. Spray enough foam into the bottom of the bag to fill almost 1/4 of the box's height.
Pull the edges of the plastic bag up over the foam and fold it over the top to completely cover the foam.
Place the object you want to ship on top of the foam-filled plastic bag. The foam will continue to expand up and around the item.
Place a second heavy-duty plastic bag on top of the item you are shipping. Spread the bag so it will be easier to spray foam into the bag.
Add enough spray foam to fill approximately 1/4 of the box's height or about the same amount as you sprayed into the first bag.
Fold the top bag over the second batch of spray foam to keep it contained and seal the box. Ship as usual.