On March 27, 1933, two organic chemists working for the Imperial Chemical Industries Research Laboratory were testing various chemicals. To R.O Gibson and E.W. Fawcett's surprise the white, waxy substance they were testing would become a revolutionary substance that would change the world. Polyethylene was born!
The researchers set off a reaction between ethylene and benzaldehyde, in an autoclave. It seems their testing container sprang a leak and all of the pressure escaped. There was the white, waxy substance that greatly resembled plastic. Upon carefully repeating and analyzing the experiment, the scientists discovered that the loss of pressure was only partly due to a leak; the major reason was the polymerization process that had occurred leaving behind polyethylene. The first patents for polythene were registered in 1936 by Imperial Chemical Industries. A year later the first practical use for the material, as a film, was discovered. In 1953 Karl Ziegler of the Kaiser Wilhelm Institute and Erhard Holzkamp invented HDPE (High Density Polyethylene). From there, two years later, in 1955, HDPE was produced as pipe. Ziegler was awarded the 1963 Nobel Prize for Chemistry.
Did you know that polyethylene played a key supporting role during World War II? It was first used as an underwater cable coating and then as a critical insulating material for vital military applications as radar insulation. This is because it was so light and thin that it made placing radar onto airplanes possible thus vastly reducing the weigh. The substance was a highly guarded secret.
After the war, polyethylene became a tremendous hit with consumers It became the first plastic in the United States to sell more than a billion pounds a year. It is currently the largest volume plastic in the world.
Today, Polyethylene has the advantages of excellent moisture-vapor, chemical, and electrical resistance. It is widely used for making containers, wire cable insulation, pipe, linings, coatings, and engineered films. It is used to power transmission, consumer goods, packaging, electronics household good and more. Its principal disadvantage is poor mechanical strength, unless it has a little help from scrim reinforcement! Developments in technology continues to improve its functionality making it the most efficient use of natural resources petroleum and natural gas. We applaud these scientists for creating polyethylene that is used in a variety of plastic sheeting products today.
Polyethylene is the largest volume polymer produced globally, with over 90 million metric tons per year!
What do we mean when we say, "Heavy Duty Plastic Sheeting"? The dictionary defines "heavy duty" as, "made to withstand hard use or wear" and "made to withstand great strain or use". So when Global Plastic Sheeting refers to "heavy duty plastic sheeting", we are referring to a plastic sheeting product that is made to withstand hard use or great strain based on the application the plastic sheeting was designed for. Therein lies the difference. A plastic liner is not heavy duty in every application it is presented with. A liner/ film is heavy duty when the plastic was engineered specifically for an application and the film is capable of doing the job it was designed for. It will stay strong, and protect what it was employed to protect.
Let's take surface protection films. These are films that are engineered to cover a variety of surfaces in the most expeditious way possible. Carpet plastic is made to stick to carpeting without transferring the adhesive onto the carpet; hold up under the PSI pressure that a ladder could place on the plastic, have a tight enough cell structure that any fluids that land on the plastic won't permeate onto the carpeting; and continue to do its job protecting the surface of the carpet for the time period it was engineered for- usually 30 to 45 days. Can any type of plastic do this job? Absolutely not. Plastic known as "visqueen" that you find in big box stores won't hold up to the riggers like a virgin polyethylene will. Some products that have adhesive come from overseas where they don't have the quality control that we have over our plastic and our adhesives. What can happen is this foreign film can discolor you carpet due to a petroleum based adhesive. All the films that Global Plastic Sheeting offers we consider to be "heavy duty plastics" because this are rough and tough when used where directed.
It's tricky for consumers to really understand what goes into making these films. On the surface they look like, well- plastic. But just like cars for the most part all looks the same, there are a great degree of differences that explain why one may be better suited to be a race car versus a family car. What is under the hood came make a huge difference. We offer hundreds of different types of plastic sheeting that perform different duties.
What about Fire Retardant Films? Again, plastic looks like plastic. When you feel it you might notice one is thicker than the other. One is sticky on one side, or one is black and one is white. How is that important? Plastic is an amazing animal. In the lab, additives can be added to the films to make the perform double duty. Take fire retardant plastic (flame resistant plastic). A fire retardant additive is mixed in with the plastic so what when a flame comes in contact with the film, the plastic will not add to the fuel source. This heavy duty fire retardant film will not burn. It may melt due to the extreme heat, but it will not burn. This constitutes being heavy duty because the flame resistant plastic is doing what it was designed to do- withstand hard use- extreme conditions.
Another liner/ film that falls into the category of "heavy duty plastic" is a liner called, HDPE. HDPE stands for high density polyethylene. This plastic which is also called a "geomembrane" is engineered with a specially formulated polyethylene resin. It contains approximately 97.5% polyethylene, 2.5% carbon black and trace amounts of antioxidants and heat stabilizers; no other additives, fillers or extenders are used. What you get is a film that has excellent chemical resistance, very low permeability- high tensile strength and more. This liner stands up to UV radiation and can survive outside in harsh conditions. Now that is heavy duty!
Containment plastic must be heavy duty as well to do its job correctly. What is contaiment plastic? It is plastic that is used to cover the object that needs covering. Take scaffolding. You have seen where it is covered in plastic- that is a specialty plastic called heat shrink wrap. This engineered plastic is made to shrink when heat is applied to tightly cover the building, boat, or object it is protecting. Pictured below is the Mars Rover protected by our specialty heat shrink wrap called, GPS Anti-stiati Fire Retardant Heat Shrink Wrap.
Can greenhouse plastic be heavy duty? Absolutely. Take SolaWrap greenhouse covering film. This bubble wrap looking plastic will last 10 years in the hashest of environment. It is made to withstand heavy snow loads, high winds, sun, heat, rain- you name it...and it won't yellow or degrade. Other greenhouse covers made from 6 mil polyethylene will only last a few year. And while they will get the job done for a time period, they are not as heavy duty as Solawrap. Here you see SolaWrap on a commercial greenhouse for Proven Winner. SolaWrap goes the distance.
Hopefully now you have a better understanding of what we mean by, heavy duty plastic sheeting when we refer to our product line. Products that do what they say they will do make life a little easier.
Is it that time again to replace your greenhouse covering? Are looking for the best greenhouse plastic you can find. This article will look at the greenhouse covers that have been on the market for years in the US and then present a proven product that has a track record of 30 years in Europe, but if fairly new in the United States. It is like nothing else that currently exists on the market. You will see that it outperforms all its competitors, and is more cost effective in the long run.
What factors are you taking into consideration for your greenhouse? You are probably considering the amount and type of light reaching your plants, the overall appearance of your greenhouse, its ease of maintenance, safety and longevity. Most of all, you want something that is cost effective.
What are your choices? Let's start with polyethylene films. It comes in a variety of thicknesses with 6 mil being very common. When selecting a 6 mil greenhouse plastic, you need to make sure it is not a product out of China. The Chinese made films are not made with virgin polyethylene which degrades in the sun! Some people chose to use a double layer for better insulation. Typically a single layer of polyethylene film has an R value of approximately 0.85. A double poly cover consisting of two layers of poly has an approximate R value of 1.25. This is a quick inexpensive fix- but is it really inexpensive when you add in the labor cost to replace it more often than other options. Greenhouse plastic will offer some UV protection, and some versions have better tensile strength than others.
One thing to be aware of is the plastic ripping where the plastic touches the PVC. This seems to be reported from growers who don't use a film that offers UV protection The PVC may absorb the heat and speed up the breakdown of the plastic. As we all know, sun is an enemy to all sorts of plastic sheeting. Another reason for the breakdown and tearing of the plastic could be the chlorine that is in PVC. This too is a problem for greenhouse plastic. There is a polyethylene greenhouse film that won't give you these problems called SolaWrap! Read on to learn more.
6 mil greenhouse plastic coverings also come in white. They are often referred to as, white opaque greenhouse films. White greenhouse films are popular when reducing heat in the greenhouse is the goal. Being white will however reduce the light transmission by almost half per layer.
Another option is to look at the reinforced polyethylene greenhouse films. This product comes in a 3 ply laminate where a cord grid is placed between two layers of plastic. The goal is to offer a high strength film that is durable yet light weight.
Polycarbonate Panels: Another route that has been popular in the past is polycarbonate panels. This is a translucent rigid plastic. Some compare it to glass as it is almost as transparent. It can be installed as a corrugated single layer, or in a flat twin wall version. By doing a twin wall you create air pockets between the two walls which act as insulators. Due to its glass like quality, it offers good light transmission. People like that it is a light weight material that can be cut to size and installed.
Glass: Glass is one of the least efficient materials for retaining heat because it has very little insulating value, and it transmits heat and cold quickly. Consider thermometers are made from glass.
Glass is much heavier than other coverings and needs substantial framing. It doesn't diffuse light so plants could get burned; glass breaking is a huge hazard. Consider climates that have heavy snow loads and hail storms. If the foundation or the frame shifts for whatever reason, the glass can crack. Another consideration is heat loss due to gaps between the panes. It's important to have an installer who is experienced. It's not something that most weekend gardeners can throw up.
SolaWrap Greenhouse Plastic Cover: SolaWrap Greenhouse Plastic (Greenhouse covering) offers:
- R-Value 1.7
- 83% transparency
- 10 year warranty against UV degradation (better warranty than polycarbonate)
- up to 83% diffused light (only product on the market with both high transparency and high diffusion)
- 120 lbs per square foot snow load rating (approx 15 feet of snow)
- 100 mph wind rating (has survived 135 mph windstorms in Alaska)
- Has been shown to last up to 27 years on greenhouses in Europe
- Does not yellow or get brittle
Pictured above the greenhouse that Proven Winners built using SolaWrap. More and more commercial growers in the U.S. are becoming familiar with Solawrap, and are selecting it. The bubble structure offers amazing benefits when compared to the other products on the market.
SolaWrap has withstood many a hailstorm, snow load, and all out terrible winters. There is no need to worry about hail storms and the resulting broken glass!
To find out more about SolaWrap, please call us at 855 Sola USA (855.765.2872). Happy Growing!
Question:Can you recommend a tape to hold plastic together for a pond liner that is waterproof? Does such a waterproof tape even exist?
Answer: Ye, waterproof tape does exit! Taping pond liners can be tricky business. Common types of liners expand and contract over temperature ranges, and the liners commonly used can expand and contract by as much as 5%. This alone makes successful taping of liners a challenge. As ponds are filled with water, the liner settles, and the water stretches the liners. Any taped seams are put under additional stress. There are waterproof tapes on the market, which can be used for this purpose if there is no other choice, and for repairs.(Click here for waterproof tapes_ 225 Fr tape, Butyl tape.) My highest recommendation goes to lining the pond with a one-piece liner, or one that can be welded in the field. Global Plastic Sheeting, Inc. offers a nice selection of pond liners made from 100% virgin resins.
What ?? Flame resistant plastic sheeting, really? Does it come in Clear, white, black? Flame resistant flexible plastic comes in white and black, but it does not come in clear when it is made from polyethylene. The reason being that the fire retardant/ flame resistant additive is white! It is common to find this plastic in a Black plastic sheeting that is fire retardant? Why would anyone want it, and what advantages does it offer me? What makes the GPS Black Plastic Sheeting any different than what I can get at the home improvement stores? Why is it important to use during Halloween for example?
First, polyethylene is highly combustible in its natural form, and makes what Fire Marshal's deem a "VERY EXCITING FIRE"once it is on fire. Because polyethylene is made from oil and natural gas based compounds, it is highly flammable, and burns at very hot temperatures.
Polyethylene is used everywhere. If you keep your eyes open, you will see it every day- on construction sites, in homes and offices, black plastic at haunted houses, flea markets, warehouses are full of it, packing supplies are made from it, toys, auto parts, most foreign cars (just threw that in for giggles!), anyway you get the picture. Poly makes a fire burn much hotter and faster, and is an accelerant. This causes people to get hurt, and unfortunately, in numerous cases every year, people lose their lives because of plastic sheeting or other types of plastics. This is why FR plastic is important for Halloween. If people have a candle or a lighter, you don't want the plastic catching fire. It's important to buy an FR plastic that is cerified as Fire Retardant. There are I am sure you can all remember hearing of fires in night clubs, where plastic caught fire, and many people were trapped. This is avoidable, and with some education, people can make choices that keep these tragedies from happening.
Through chemistry, the plastic industry has been able to make most polyethylene, regardless of form (even most foreign cars) using plastic that is deemed "Flame Resistant". First, let's get an idea what this term means. Making a highly combustible material, like polyethylene, Fire Retardant (FR) or Flame Resistant means that we take away its ability to contribute significantly as a fuel source in a fire. This can be done at various levels and there are countless tests available today to help certify the levels of just how FR these products have become. Some of the most popular are the NFPA 701, ASTM E-84, UL-94, California Fire Marshal Title 19, just to name a few.
To simplify this, additive packages are added to the resins used to make polyethylene products causing the finished product to be fire retardant.
Today, we are able to engineer the additive levels so that the products can pass the FR tests needed for most applications and industries. A few applications for FR polyethylene that did not even exist as little as a decade ago are such things as: Black Polyethylene Sheeting (Black Plastic Sheeting) for haunted houses, Housewraps, Vapor Retarders, Construction Tarps, Enclosure Films, Abatement Plastics, Automotive interior parts, FR tapes, Airplane Covers, Military Applications Galore, Temporary Shelters, Humanitarian Aid, Cargo Covers, Surface Protection Films, Pallet Covers, Heat Shrink Wrap, Theatrical Plastics used on stages, Dog show plastics, Industrial Plastic Sheeting, Spray booths, and the list goes on and on.
The reason for the increased popularity in FR polyethylene over such a short period of time is that the increase in fire safety is so substantial, and the cost difference is so small that it just makes sense. When fires strike, and they strike often, using FR products of any type keep the loss of property to a minimum, and more importantly the loss of life and injury as small as possible. More and more specifications are calling for FR products, and this is a great thing for all of us. After all, when was the last time you checked to find out if that housewrap they used to build the walls of your house was Fire Retardant? Please watch for future posts on this subject, because this hot topic is just heating up.
At last we have a heat shrink wrap film that has ultra violet resistance, is fire retardant, and is also anti-static! The "all-in- one" implication for offering both anti-static and fire retardant characteristics to the film is pronounced. This film is fire certified to the NFPA 701. If you are wrapping equipment that has electrical motors, semi-conductors, or cannot withstand static discharge, the anti-static property will minimize the chances of a spark. Take the Mars Rover for example..it was wrapped with this proprietary film as pictured below!
Wrapped by the Shrink Wrap Pros!
Heat shrink wrap film is one of the most versitile, useful ways to protect and encapsulate odd shaped objects of all sizes- (like the rocket pictured below from one of GPS's customers). Heat shrink wrapping is used becasue it offers a containment that is strong, durable, and require little mainenance.
Heat shrink wrap film (often referred to as, shrink wrap film/plastic) is made from virgin polyethylene resin, the most dependable film for the job. It shrinks when heat is applied, encapsulating the object in a secure manner. This encapsulation insures that the elements such as wind, rain, snow won't have access to the item.
Heat shrink wrap film comes in a variety of thicknesses and colors to better suit the application. The thicker films are more durable for more demanding applications. The thicknesses range from 6 mil, 7 mil, 8 mil, 9 mil, 10 mil, and 12 mil.
There are three standard colors. White is the most common. It is used for reflecting heat, and does well in all weather conditions. White is often used for transportation as a cover. Blue is well suited for areas with snow since it absorbs heat which helps the snow to slide off. Clear works well when you want to see what is covered since you can see through it.
Heat shrink wrap can also come in a flame/fire retardant version which will quickly extinquish the wrap should it come in contact with flames. Meeting NFPA 701, the FR heat shrink wrap is popular with shipyards, scaffolding, factories, or any application that requires the materials to be fire retardant.
.There are hundreds of uses for heat shrink wrap film. Ten of the most pouluar uses are:
- Use in construction on scaffolding to wrap buildings
- Scaffolding wrap containment for bridges/ construction
- Marine uses such as wrapping boats, and marine equipment
- Disaster relief projects for covering damaged buildings and roofs
- Wrap and protect large equipment of all shapes and sizes
- Shrink wrap pallets for freight
- Shrink wrap items that will be transported or packaging
- Winterize items for storage
- Environmental containment for safe removal of lead and other hazards
- RV wrap
If you would like to know more about this product click here, or call 866.597.9298 and ask for Ken!
What is meant when someone mentions “flexible plastic sheeting” ? What kinds of “flexible plastic sheeting” are there? Are there different types? And what are the additives used to make flexible plastic films?
In its simplest terms, the main difference between the different types of plastic is the way their cellular structure, or molecules bond with each other, and how tightly they are formed. Beyond that, this incredible polymer allows us to add additives to improve the performance of the plastic.
Which is the most flexible of them all?
Linear Low Density Polyethylene (LLDPE) is the most flexible of the plastic sheeting films. LLDPE is blended form of LDPE where the film has much more flexibility, tensile strength, and more conformability. It is more pliable and softer. LLDPE is used for pond liners or blended into other films to give them more flexibility and extra strength. LLDPE is used for films that need a tremendous amount of strength to absorb impacts while not tearing or puncturing. An example of this is a carpet plastic film that adheres to the carpet. It is strong enough to withstand foot traffic, even from stiletto high heels! The molecules all line up and strongly hold together as the film is stretched. The most common thickness range is from 0.5 mil to 40 mil in flexible plastic sheeting.
Which is the most common of them all?
Low Density Polyethylene (LDPE) is the most common type of plastic sheeting. It is very flexible, most often from 0.5 mil thick to about 40 mil in flexible sheeting forms. Due to its flexibility is conforms well to a variety of surfaces. The downside is that this LDPE is not as strong or dense as some other types of plastic sheeting. It is not nearly as puncture resistant either. LDPE is used quite widely in construction, agriculture, surface protection applications, covers of all sorts, tarps and much more.
Which is least commonly used of them all?
Medium Density Polyethylene (MDPE) is the least commonly used form of polyethylene for flexible plastic sheeting. Its positive attributes is that it is stronger than LDPE and has a little more chemical resistant. It has a tighter cell structure making it more tear and puncture resistant. When pond liners are manufactured they are often made with MDPE and blended with LDPE or LLDPE to achieve a strong yet flexible pond liner.
Which is the toughest of them all?
High Density Polyethylene (HDPE, aka HD), has the distinction of being the strongest, toughest, most chemical resistant and least flexible of the four types of flexible plastic sheeting referenced in this article. HDPE is also the most UV resistant- holding up to the harsh rays of the sun without needing UV additive packages. HDPE’s strength comes from its tight cell structure that makes it very difficult for other molecules to pass through its structure on a microscopic level. When applications call for very large liners such as pond liners, HDPE is the most easily seamed or “sewn” together. Used industrially, the thickness range from 12 mils to100 mil thick. HDPE is used as secondary containment liners for oil tanks, and most industrial ponds and canal liners where chemical resistance is needed.
What Additives can be added to the plastic?
Anti-static: An anti-static additive can be added to polyehtylene to make it resist sparking. Anti-static films are used in the telecommunication industry as one example. Certain types of equipment can be prone to sparks which could result in a devistating fire. Anti-static fire retardant films solve this problem.
UV Stabilizers: Sunlight eats up plastic. Perhaps you have seen black plastic on piles of dirt that are flapping in the wind? That is because that torn plastic didn't have any UV stabilizers to combat the strong rays of the sun. Heavy duty plastic sheeting adds these stabilizers for films that will be used for ponds, covering anything outdoors, exposed to sun light.
Color/Pigment: It's no surprise that pigment can be added to polyethylene to make the plastic look a certain color. Just about any color can be created.
Flame/Fire Retardant: Plastic goes up in a flash if it is exposed to an open flame. Today there are fire retardant films that when exposed to a flame will not add to the fire. They will self extinguish. Note that the plastic may melt, but it won't be a fuel souce to the fire.
Sip/Anti-block agents: This additive is used to improve film to film slipping.
External Coatings: Coatings can be applied to the surface of the plastic, which is designed to help wet out the surface of the film. This in turn decreases the contact angle of the water dropplets and improves transparancy.
There are so many varied uses for plastic sheeting which is often referred to as "Visqueen" Plastic sheeting is a polyethylene film that comes in many different colors and thicknesses. It also comes in a variety of grades or qualities.
Grades of Plastic Sheeting
"Virgin Polyethylene" is the highest form of plastic sheeting today. This varies wildly from Visqueen. Visqueen has become one of the generic names for plastic sheeting, just as Kleenex has become the generic name for tissue. When someone asks for Visqueen, they are referring to a lesser grade of plastic sheeting. The plastic sheeting known as Visqueen has become a generic name for Construction and Agricultural Grade Polyethylene sheeting (C&A film). C&A film contains up to 25% post consumer recycled content, and is made from the least expensive resins available at any given time. While it is excellent for use in many projects, it is not ideal for any use that requires sustained strength such as a tarp or for use as a vapor/moisture barrier or retarder. People will often do a search for "visqueen vapor retarder", or fire retardant visqueen" when they may be looking for an engineered plastic. An engineered plastic is one that is intentionally designed to meet certain measurable criteria to insure its suitability for the job it is intended for.
The thickness of polyethylene is measured in mils, which equals one-thousandth of an inch, or 0.001 inch. Many of the local hardware or box stores will carry very light duty plastic sheeting that could be 1 to 2 mils thick. Depending on the application will dictate how thick the plastic needs to be. 6 mil is a very common thickness for plastic sheeting- but it can go all the way up to 100 mil!
There are so many different roll sizes, thicknesses, and colors on the market. Here are a few examples:
Notice in the above examples that the last two examples have additives added to them. An anti-static additive as well as a fire retardant additive can be added to make the plastic both anti-static and fire retardant.
Great Uses for Plastic Sheeting:
- Shelters or Temporary Protection
When hurricanes strike or disasters ensue, its plastic sheeting that is often used to create temporary shelters. Often string reinforced plastic is used because it is stronger and will hold up to wind.
- Coverings for Outdoor Equipment, Wood Piles, Furniture
String Reinforced plastic sheeting is commonly used as well as non-reinforced plastic to make covers for a variety of items. Grommets and hems can be added to the plastic so it can be held down in place.
- Waterproofing Ponds, Lakes, Canals
Liners for ponds, lakes and canals use a variety of plastic sheeting called, High Density Polyethylene or HDPE to line their basins. This virgin poly will hold up to the sun and elements.
- Recreational Uses such as Ice Skating Rinks, Slip and Slides
The beauty of plastic sheeting is it can be engineered for specific uses. With the addition of special additives, plastic sheeting can work long and hard for the application it was designed for. Ice skating rinks and slip and slides are an example of this. Very large or long rolls of plastic can be ordered from a manufacturer to serve these purposes.
There is special plastic sheeting that does not harm fish or humans and can thus be used for rain collection or aquaponics. Plastic can leach out chemical especially if it is construction and agricultural grade- as that plastic is mixed with regrind that is not pure virgin polyethylene.
- Closing Off Rooms for Remodeling
With the help of an amazing product called ZipWall which will hold plastic sheeting up to the ceiling- you can close off a room where work is being done. This is especially great if dust is flying around from workman activities.
- Abatement work for Lead Paint
Lead paint abatement is a big deal. It is very important that lead paint that is being scrapped off a surface does not contaminate other rooms in the house. This is a great place to use plastic sheeting. Anti-static fire retardant plastic is a great choice for this application because the lead dust won't stick to the plastic sheeting. It can be swept up and removed.
There are full lines of plastic that have adhesive on one side so they can stick to the surface they are protecting! Each type (Carpet Plastic, Tile Plastic, Countertop Plastic, etc) have specially formulated adhesive so it sticks just right to that surface. For example, you need a stronger adhesive to stick the plastic to carpeting than you do for plastic being applied to counter. Self-adhesive plastics are great for protecting surfaces from dogs, children's activities, adult parties and more!
- Black Out Curtain for Halloween, Movie Sets, Museum Work
Black fire retardant plastic sheeting is used all the time by commercial haunted houses, movie sets, aerospace companies and museums to list a few. This plastic is certified to be fire retardant- thus not contributing to a fire should one ensue.
Plastic polyethylene sheeting has been used for years and years to create greenhouses. Today there are state of the art coverings for greenhouses that last a lot longer than the old school 6 mil plastics of yester-year. This remarkable product is called, SolaWrap! It is plastic sheeting with bubbles in the layers. The bubbles act to insulate the house from heat and cold, while adding strength. There are a lot more attributes that you can learn about by clicking on the link.
Bottom line is, plastic sheeting is a work horse for a variety of projects.
Are you ready to toss a fabulous salad with lettuce that you grew yourself? It's much tastier, healthier, and fulfilling to know you grew this lettuce yourself. In no time you will have your own lettuce on the table.
Tip #1: Get a Beaver Plastic Lettuce raft (click here) which will float on top of the tank/aquarium you are going to use for your aquaponics system.
Tip #2: You will need a container to hold water. An aquarium or any clean container that can hold more than 10 gallons of water will work.
Tip #3: Next you need a means for moving the water around and a way to filter it. Your filter needs to pull water through the gravel to promote bio-filtration. Either an air pump and air stones can be used, or you can get power heads that have an active water pump that draws the water up the riser tubes of the filter. This method is called a RAS raft system or Recirculating Aquaculture System.
If you are wondering why we are not adding fish to the aquarium- Some people contend that if you float rafts in fish ponds, the contaminants in the water cover the roots, keeping them from absorbing the water and nutrients for them to grow. In an informal side by side test, the plants without the fish did much better.
Tip # 4: Aquarium gravel is a must- so much so that you will need 2 inches of gravel to put under your filter. Aquarium gravel is preferable since int won't leach into the water.
Tip #5: Now you need the seeds and the grow media that you will place in the lettuce raft.
Tip #6. pH seems to be the key to life in so many areas. It's the key to the success of your growing lettuce in your lettuce raft as well. Get a pH test kit to maintain the proper pH.
Tip #7:Good light either from a window or a grow light is a must.
With these few components you have the start to growing lettuce in your lettuce raft.
How is Polypropylene different from Polyethylene? Well.....
Polypropylene, also know as polypropene is a form of plastic just as polyethylene is. What separates polypropylene from polyethylene for starters is the fact that polypropylene can be molded in essence becoming pliable above a certain temperature. When it cools it will return to its solid state. Polypropylene can be used not only as a structural plastic, but it can be used as a fiber. It also has a high melting point, which differentiates it from polyethylene. One area where polyethylene has over polypropylene is that polyethylene is more stable. Polypropylene has the advantage that it can take repeated motions such as being a hinge. A hinge made out of polypropylene can be opened and closed many many times, and hold up just fine. This is known as having "good resistance to fatigue".
Polypropylene can be combined with other materials, as can polyethylene. Rubber for example can be added, to make it more pliable. One of the exciting additives that is added to polypropylene are minerals. These minerals allow a polypropylene sheet to become a synthetic paper. synthetic paper is essentially plastic paper. It can be easily printed on. It can be folded, hot stamped, die cut, sewn and more. Best of all it is environmentally friendly! All of a sudden polypropylene is transformed into a slew of products. Synthetic paper made from polypropylene is used to make banners, membership cards, maps, menus, phone cards, signs, tags, floor graphics, counter mats, and booklets. The list goes on from here! What is outstanding about synthetic paper is that is is durable, tear and water resistant!
Polyethylene has more demand however than polypropylene. Polypropylene is used extensively in the automotive industry as well as the packaging industry. 70% of the polypropylene uses is for packaging needs for the food industry. It can be made into bottles, food containers, food crates and pallets.
Polypropylene is used to make house wears, appliances and toys. It is also used to make make carpeting and upholstery. The polypropylene is heated and made into fibers. There are so many uses for both polypropylene and polyethylene.
Polyethylene is inert, translucent and creates a lower static charge than polypropylene. That makes polyethylene a candidate to be a sleeve to house collectible documents. It is "inert" and cannot product mold or mildew. It is also translucent in nature so it allows less light through it than polypropylene. It has a lower static charge than polypropylene so it attracts less dust and dirt. Polyethylene costs more than polpropylene because it has a higher purity (100% virgin).
Here is a list of some of the differences between polyethylene and polypropylene:
- Polyethylene and Polypropylene are very similar as far as physical properties.
- However, Polypropylene can be produced optically clear where polyethylene can only be made translucent like a milk jug.
- Polyethylene does have physical properties that allow it to stand up better in cold temperatures, particularly when using it as signs.
- Polypropylenes are light in weight. They have a high resistance to cracking, acids, organic solvents and electrolytes. They also have high melting point and good dielectric properties and are non-toxic.
- Monomer of polyethylene is ethylene and monomer of polypropylene is propylene.
- Polyethylene has a lower melting point compared to the higher melting point of polypropylene. (this may be a good test for you)
- Polypropylene is not as sturdy as polyethylene.
- Polypropylene is stiffer and resistant to chemicals and organic solvents compared to polyethylene.
- Polypropylene is pure, non-stretching and generally more rigid than polyethylene.