Step 11: Foam in Place
Note: There are two types of foam available. One cures rigid and the other remains soft (like seat foam). Given the possible expansion of carbonated beverages, the soft foam was used for this project.
With the plastic bottle and o-ring in place, turn the tank over and fill with foam through the Bottom Hole.
Note: Be sure to plug the tank's drilled-out pressure relief Valve Tube, or foam will flow out this hole. A small wad of aluminum foil stuffed in the hole works well.
Insert the applicator straw to the bottom of the inverted tank and slowly spray the foam. It will expand, so several small shots, a minute or so apart, will help to keep from grossly over filling the tank.
Note: This foam needs moisture to cure so, the inside of the tank was spritz with a water mist before foaming, and in between the several small shots of foam.
After the foam expansion slows (minute or so), scrape off the excess foam. Leave about 1/2 inch of foam above the tank. This foam will be used to adhere the Bottom Cap.
While the foam is still tacky, press the plastic Bottom Cap in place on the bottom of the tank. Clean off any foam that may squeeze out.
Be prepared when using this foam! This can be a messy operation.
Urethane foam sticks to everything; including skin. Once cured, the only way to get it off skin is to let it wear off - there is no solvent.