Mylar, Foil, Foylon and Reflective Hydroponic Surfaces
Light not reaching your plants is wasted light. In a hydroponics setup- light is money.
A reflective surface in a hydroponic grow room optimizes the use of available light and decreases the need for expensive lighting, making it highly cost effective. The correct reflective surface can increase the amount of light plants receive by up to 30%.
Choosing the right reflective material is vital to the success of your harvest.
Hydroponic lights are placed above the plants, just as the sunlight is above them in nature. Reflective surfaces, when properly placed help to provide light and heat to all portions of the plants.
To optimize results the walls should be as close as possible to your plants to avoid wasting light and energy. Early Hydroponic growers experimented with aluminum foil and mirrors , in much the same way early aviators experimented with flapping their arms to simulate flight - neither method is very effective.
Aluminum foil is only 55% reflective at its best. Once it is crinkled , creased or torn that value drops significantly. It creates hot spots and conducts electricity which makes it a hazard under some conditions. It is considered a fire hazard when used in conjunction with HID Lights. Should you decide to use it temporarily be sure that the dull side of the foil is the one that is used to reflect the light.
Reflective Paints and Coatings
Simple Flat white wall paint is actually better than either of the aforementioned. Semi gloss and High Gloss paints are not good for grow rooms as they cause hot spots and frequently bounce light around in the wrong directions.
Titanium white paint is actually the best- but its cost is prohibitive.
Flat white paint is less expensive and will reflect about 75 of the light, and it doesn't create hot-spots. Once disadvantage to most paints is that they will sometimes promote the growth of mold and fungus, so adding a fungicide is recommended.
Elastomeric paint is basically a mildew resistant rubberized roofing paint which will reflect 90% of the light.
Polystyrene is also sometimes used , it has reflective and insulating qualities and is suitable for grow rooms where insulation is essential.
It will not only keep cold out , but it keeps heat in. Needless to say - good ventilation is required. Being lightweight it is suitable for mobile or temporary setups.
Mylar is a highly reflective polyester film available in varying thickness, generally 1 and 2 mm thicknesses. The thicker the mylar the more durable it will be. Thinner mylar will naturally tear more easily.
Maintenance , such as basic cleaning will frequently damage or destroy 1mm mylar. Mylar reflects up to 97% of available light when it is un-creased or torn. It is the most cost effective in the short run.
Foylon, another more durable and more expensive version of Mylar has comparable reflective qualities but is more durable, it won't tear , crease or discolor as easily. In the long run , considering that is not as easily damaged Foylon is generally more reflective. Foylon is made of reinforced foil laminate spun with polyester fabric. It is resistant to most cleaning and nutrient solutions, doesn't fade over extended periods.
Another type of Mylar is C3 anti-detection film
C3 is comparable to 2mm thick mylar, the difference is that it is also 90% infrared proof. The infrared proof attribute is favored by those growing controlled substances, who wish to avoid detection via IR scanning.
Mylar and its cousins Foylon and C3 can be attached to walls with Velcro, which reduces the risk of tearing, creasing or bending when taking it down for cleaning..
It needs to be flush with the walls to avoid air pockets which can create hot spots as well as harbor fungus and mildew. The thinner 1mm thick mylar stands a fair chance of being creased or ripped in the process when Velcro is used to attach to the walls.
Panda Film is another highly reflective and cost effective alternative to mylar. Although it is not as reflective, it is somewhat comparable. It is black on one side ,white on the other and about 6 mils thick. It needs to be replaced every other year as it becomes brittle.
The white side reflects light back into the foliage of crops. The black under layer stops light reaching the soil in a greenhouse scenario , in hydroponics - with no soil it helps to prevent algae growth, which is a problem in some grow rooms. Related Article - Algae Buildup in Hydroponics
Adequate ventilation is essential if mylar, its cousin foylon or any wall coating is being used in your grow room. Hot spots , or excessive moisture will cause discoloration and hence reduced reflectivity. Moist spots and condensation from excessive moisture will also cause damage to the reflective surfaces, both temporarily reducing the reflective quality as well as more permanent damage.