sawhorseray wrote:3 & 4 inch PVC is most commonly used as waste pipe, going to be hard to find as "food grade" anywhere.
True, Ray, the big stuff is most commonly used as waste pipe, but the smaller stuff is used for water supply pipe, so I wouldn't shy away from PVC. Just don't use "used" PVC. (Sewage! Yuck!)
I looked around on the internet, and found the following 5-year article which may be of general interest.
That same article gives a good summary of the different types of plastic. A portion of it reads:
Types Of Plastic
In the United States, the following codes represent the seven categories of plastic used in nearly all plastic containers and product packaging:
<1>PET or PETE (polyethylene terephthalate) is a clear, tough polymer with exceptional gas and moisture barrier properties. PET's ability to contain carbon dioxide (carbonation) makes it ideal for use in soft drink bottles. Examples: Soft drink bottles, detergent bottles
<2>HDPE (high density polyethylene) is used in milk, juice and water containers in order to take advantage of its excellent protective barrier properties. Its chemical resistance properties also make it well suited for items such as containers for household chemicals and detergents. Most five gallon food buckets are made from HDPE. Examples: Milk bottles, shopping bags
<3>Vinyl (polyvinyl chloride, or PVC) provides excellent clarity, puncture resistance and cling. As a film, vinyl can breathe just the right amount, making it ideal for packaging fresh meats that require oxygen to ensure a bright red surface while maintaining an acceptable shelf life. Examples: Plastic food wrap, shrink wrap, garden hoses, shoe soles
<4>LDPE (low density polyethylene) offers clarity and flexibility. It is used to make bottles that require flexibility. To take advantage of its strength and toughness in film form, it is used to produce grocery bags and garbage bags, shrink and stretch film, and coating for milk cartons. Examples: Squeeze bottles, dry cleaning bags
<5>PP (polypropylene) has high tensile strength, making it ideal for use in caps and lids that have to hold tightly on to threaded openings. Because of its high melting point, polypropylene can be hot-filled with products designed to cool in bottles, including ketchup and syrup. It is also used for products that need to be incubated, such as yogurt. Many Cambo, Tupperware and Rubbermaid food storage containers are made from PP. Examples: Bottle caps, take-out food containers, drinking straws
<6>PS (polystyrene), in its crystalline form, is a colorless plastic that can be clear and hard. It can also be foamed to provide exceptional insulation properties. Foamed or expanded polystyrene (EPS) is used for products such as meat trays, egg cartons and coffee cups. It is also used for packaging and protecting appliances, electronics and other sensitive products. Examples: Plastic foam, packing peanuts, coat hangers
<7> Other denotes plastics made from other types of resin or from several resins mixed together. These usually cannot be recycled.
Another important type of plastic is polycarbonate, a clear shatter-resistant material used in restaurant food storage containers and recently in the Rubbermaid Stain Shield line of home food storage containers.
Let me conclude with a few of my own comments. (I was a chemical engineer, and worked around R&D and production facilities for polystyrene, polyethylene, polyethylene terephthalate, polyacrylonitrile, vinyl acetate, cellulose acetate, and several other polymers for 43 years.):
(1) Bear in mind that the contact between your patties and the patty-making equipment is on the order of seconds, so plasticizer migration will be practically nil. Storage in plastic containers would obviously be much more of a concern.
(2) Polycarbonate is the plastic which has been much maligned lately as containing a monomer, bis phenol A, commonly called BPA in the press. It is present in miniscule amounts, but miniscule may be too much in some people's opinion, so avoid it if you are a stickler for purity.
(3) Polyacrylonitrile is used in clear meat packing trays. It was, early on, a contender for the carbonated drink bottle market now supplied almost exclusively by polyethylene terephthalate, PET. However, in a bitter battle back in the mid 1970s, major PET producer DuPont successfully lobbied to keep Monsanto's poly-acrylonitrile business out of the soft drink bottle market.
(4) Just about every polymer has a plasticizer in it. A plasticizer is a compound which looks structurally similar to the polymer so therefore dissolves easily in it, and is used in making the polymer more pliable or causing it to flow more easily during machining or molding operations. They've gone away from nearly all of the nasty ones (benzene and methylene chloride used to be great, but are carcinogens). Some are volatile; some are not. (..."new car smell," anyone?)
(5) There are lots of specialty polymers used in medical appliances and food applications (such as can liners), from nylon up to really exotic stuff. All sorts of monomers and plasticizers are out there. Interestingly, sometimes you have to prove that something is BAD before its use is prohibited, rather than the more rational approach of proving that it is NOT bad before allowing its use. ...and then, there's the food industry, which... uh...
Go figure. Genetically-modified organisms, anyone? (Just try AVOIDING 'em in the US. Good luck.)
