Aluminum Foil instead of Mylar?

Fuzzbutter

Fuzzbutter

Active Member
Hey guys,
Pretty much I'm just wondering of aluminum foil would work well enough to use instead of Mylar reflective sheets? Or would aluminum foil absorb too much light and not reflect enough back like mirrors do?
 
Brimi

Brimi

Well-Known Member
Alu foil will have very little reflection. White paint is much better. Make sure to use that matt color and not the one that get's the blank surface. The white chalk they used on old building is superb.
 
bigv1976

bigv1976

Well-Known Member
Aluminum Foil:
Aluminum foil is no more than 55% reflective - if used, make sure that the dull side is the one that is used to reflect the light. When it becomes creased its reflectivity is even lower (around 35%.) It is also very dangerous to use because it creates hotspots easily, is electrically conductive, and is a fire hazard when it is in close contact with HID lighting. Attaching this to walls is a pain and usually using aluminum tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable.​
 
303

303

Well-Known Member
Aluminum Foil is a heat conductor. 10 x 10 Sheets of Mylar at the local hydro store are $8.99, worth every penny...
 
TaoWolf

TaoWolf

Active Member
Don't tell other people this, but aluminum foil is ~97% reflective. And Mylar is just a polyester (plastic) film with an aluminum coating on it. ;P
 
bigv1976

bigv1976

Well-Known Member
TaoWolf said:
Don't tell other people this, but aluminum foil is ~97% reflective. And Mylar is just a polyester (plastic) film with an aluminum coating on it. ;P
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Wrong.


GrowRoom Reflectivity
Choosing the right surface for the walls of your grow room is very important, as up to 40% of your total yield comes from the edge, and the right wall surface can increase the amount of light those plants receive by up to 30%! Artificial lighting diminishes exponentially with distance, so it is important to ‘contain’ as much of this light as possible, and direct it accordingly. Reflective surfaces also help illuminate the lower portions of the garden, providing lower buds with light and heat energy.

To get the best results with your light and walls, it is important to get the walls as close as possible to your garden to ensure the least amount of light is wasted. As a caveat, the percentages provided are only useful as a general guideline, as they present the range of reflectivity of the particular surfaces. The high percentage presents the best possible circumstances for that material (for example a 99% reflectivity rating for mylar sheeting would be under ideal conditions - no creases, completely flat, no discoloration, etc).

The best way to determine how well your grow room walls reflect light would be to purchase a light meter and measure your light directly; then take an opaque board and hold it a few inches off one of your walls with the light meter below the board in such a fashion that the light reflects off the wall and onto the light meter. You can then compare the difference between the two and determine a percentage from those numbers, the closer the two numbers are, the better your wall reflects light. It is important that in both measurements, your light meter is the same distance from the light, otherwise your results will be skewed.

Also important to note is that radiant light energy refers to electromagnetic (EM) radiation with a wavelength between 400-700 nanometers (nm) and radiant heat energy correlates to EM radiation with a wavelength between 800-2000nm.

Listed below are some of the most commonly used materials used for grow room walls:

Foylon:

A more durable version of mylar, made of spun polyester fabric and reinforced with foil laminate. Foylon is resistant to most solutions, won't tear or fade, and can be wiped or washed clean.

A great solution for growers who are interested in long term use, and though it may be slightly more expensive than mylar, its durability will more than make up for its cost. It has the ability to reflect about 95% of the light and approximately 85% of the heat energy, so a good ventilation system should be used in conjunction with folyon.

A recommended method to attach Foylon to the walls would be using Velcro, as it makes taking it down for cleaning much easier nd reduces the risk of tearing, creasing or bending it. If this is used for your walls, making sure you get it flush with the wall with no pockets of air between it and the wall to prevent hotspots.

Mylar:

A highly reflective polyester film that comes in varying thickness, the most common being 1 and 2 mm thick. The 2mm thick mylar while not quite as durable as the foylon, is fairly rugged. The 1mm thick mylar tears fairly easily, so taking it down for cleaning is quite difficult without damaging it in the process. Both types of mylar are able to reflect approximately 92-97% reflective, giving it the potential to be more reflective than foylon, but because foylon is more easily cleaned without damaging it as well as it being harder to crease, foylon usually ends up being slightly more reflective. Important to note is that mylar reflects radiant heat energy just as well as foylon (around 85%), so proper ventilation is necessary if mylar is used in your grow room. Attaching this to walls can be done in a similar fashion as foylon, and the same caution should be used to avoid creating hotspots in your room. The 1mm thick mylar stands a fair chance of being creased or ripped in the process unfortunately, even if Velcro is used to attach to the walls.

C3 anti-detection film: (I'd sleep better at night if I had this.)

A specialized type of mylar that exhibits the same properties as the 2mm thick mylar, but in addition to reflecting approximately 92-97% of the light, it also is 90% infrared proof, making your grow room all but invisible to IR scanning. This can also be attached in the same manner as foylon or mylar, and the same caution should be used to avoid creating hotspots in your room.

Flat white paint:

Self explanatory; a great option for large grow rooms or for people who are interested in a low maintenance wall. Flat white paint has the ability to reflect between 75-85% of the light, and does not create hotspots. Adding a fungicide is recommended when painting.

Glossy and eggshell whites not reflect light as efficiently as flat white. Semi-gloss paint for example, only has the ability to reflect between 55-60% of the light. Also important to remember when using paint is that any smears or blemishes on the surface take away from how reflective the wall is so care should be taken to avoid marking or staining the walls. Titanium white paint is very reflective; however it is usually only used on reflectors due to its high cost.


White/Black plastic (also known as panda plastic or "poly"):

"Poly" is useful if you are setting up a temporary grow room or don’t want to damage the walls. Poly is easily cleaned.

The purpose of the black side is to not allow any light to pass through the plastic, which ensures your dark cycle remains dark. The white side is 75-90% reflective. Choose a 6 "mill" thickness of poly for maximum light blockage and duribility.

If this plastic is put too close to the light, you will obviously melt it so be careful!. Panda plastic does not create hotspots. Poly can be attached to the walls by using carpenter’s nails or using tape glue or similar means. This can be used as a cheap alternative to mylar if painting your grow room is out of the question.

Polystyrene Foam Sheeting (more commonly known as Styrofoam):

This is excellent for harsh environment growrooms (your attic for example), provided you have a good ventilation system and a way to keep the temperatures from rising too high (an a/c unit or similar) as it is an excellent insulator.

It is also a great material for use in a temporary setup or for use as a "travelling reflector" on a light mover, where weight is a concern. It is approximately 75-85% light reflective so it is comparable to using a flat white paint. Foam will not create hot spots. Rigid foam can be purchased in sheets, and can be used as a free standing wall or can be taped, glued or nailed to the wall, the last generally being the most successful method.

Emergency Blankets:

These are ultra thin polyester blankets that are sold in most camping stores and are constructed of a single layer of polyester film that is covered with a layer of vapor deposited aluminum.

It is not very effective at reflecting light because it is so thin. Holding it between you and a light source, many small holes are noticed at the intersections of creases and the entire blanket is translucent to begin with, this coupled with the many creases that are in it when you purchase it takes away a significant amount of it reflectivity. It is very easily creased as well which also detracts from its ability to reflect light. And while it is reflects nearly 90% of radiant heat energy, it is only able to reflect around 70% of the light.

The largest advantage of using this type of material is that it is very cheap and therefore easily replaced. Emergency blankets can create hotspots if not attached flush to the wall so it is important that no air gaps exist between it and your supporting wall. The easiest way to attach this is to use tape (Aluminum or metal tape is recommended), as it tears very easily once it is cut or punctured.

Aluminum Foil:

Aluminum foil is no more than 55% reflective - if used, make sure that the dull side is the one that is used to reflect the light. When it becomes creased its reflectivity is even lower (around 35%.) It is also very dangerous to use because it creates hotspots easily, is electrically conductive, and is a fire hazard when it is in close contact with HID lighting. Attaching this to walls is a pain and usually using aluminum tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable.​
 
Fuzzbutter

Fuzzbutter

Active Member
TaoWolf said:
Don't tell other people this, but aluminum foil is ~97% reflective. And Mylar is just a polyester (plastic) film with an aluminum coating on it. ;P
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Well I know that this is wrong simply because mylar has no metal, so it can't be plastic with an aluminum coating....

bigv1976:: Thank you, that really explained everything a lot more clearly for me :)
 
TaoWolf

TaoWolf

Active Member
Fuzzbutter said:
Well I know that this is wrong simply because mylar has no metal, so it can't be plastic with an aluminum coating....

bigv1976:: Thank you, that really explained everything a lot more clearly for me :)
Click to expand...
Don't take my word for it, but the myth that aluminium foil is poorly reflective only travels around in growing circles. In scientific and industrial use, it's properties are well known:

Technical Properties

Property
Value/Comment
Specific gravity
2.7
Weight
At 6.35 µm foil weighs 17.2 g/m2
Melting point
660°C
Electrical conductivity
37.67 m/mm2d (64.94% IACS)
Electrical resistivity
2.65 µΩ.cm
Thermal conductivity
235 W/m.K
Thickness
Foil is defined as metal measuring 0.2mm (or 200 µm and below)
Surface finish
Above 40µm aluminium foil has a brightly polished surface on both sides imparted by the rolling cylinders. Below 40µm one side has a matt finish due to the process of rolling two layers of foil simultaneously. If specified by the customer, foil can be supplied below 40µm thickness with both surfaces bright. Other surface finishes such as etched, grained or embossed can be supplied to meet particular customer needs.
Impermeability
The molecular structure of the metal provides a high performance barrier even at thicknesses under 6.5µm, the foil commonly used in liquid cartons. Alufoil is normally used with a supporting laminate of film or paper materials which further enhance the strength and barrier performance of the metal layer. A pouch laminate made up of 12 µm PET/7µm alufoil/50µm LDPE has a WVTR’* of less than 0.2 g/m2/day compared with a 12 µm PET/60µm LDPE laminate for which the WVTR is 1.5 g/m2/day.
Corrosion Resistance
The naturally-occurring surface oxide on all aluminium in the presence of oxygen in the atmosphere acts as a shield and renders foil substantially corrosion resistant. Aluminium is also chemically resistant in contact with substances in the pH range 4 to 9.
Compatibility with food and chemicals
Non-reactive except to substances of high acidity or alkalinity (see Corrosion Resistance). Resistant to most common compounds in solution.
Formability
Aluminium is very malleable and can be deformed considerably without losing its barrier integrity.
Dead fold
When fully annealed, aluminium foil retains no 'temper' and therefore retains its shape when deformed.
Non-absorbency
Non-absorbent and proof against grease, oil, water and other liquids.
Hygiene
Foil is sterile following annealing, and does not harbour or support the growth of bacteria.
Toxicity
Aluminium is present in many fresh vegetables and is non-toxic in amounts and compounds normally encountered. The metal does not accumulate in the body and is non-reactive with virtually all foods, drugs and cosmetics.
Taste, odour
Tasteless and odour-free, alufoil imparts no detectable taste or odour to foodstuffs.
Opacity
Foil is a solid metal. It transmits no light and is a total barrier to light including the UV spectrum.
Reflectivity
Reflects approximately 98% of radiant heat and light.
Non-magnetic
Aluminium is insignificantly magnetic and therefore provides excellent electrical shielding.
Recyclability
Aluminium is easily recycled. Plain aluminium foil can be compacted and re-melted. Laminated aluminium is processed to separate the supporting layers and the aluminium residue is reused in other applications. In addition, the energy contained in the thin foil component of a laminate can be recovered in the form of heat.

*Water Vapour Transmission Rate.


Material and mechanical properties


Dead fold: When fully annealed, aluminium foil retains no ‘temper’ and therefore retains its shape when deformed.

Formability: Aluminium is very malleable and can be easily deformed to a large degree without losing its barrier integrity.

Corrosion Resistance: The naturally occurring surface oxide on all aluminium in the presence of atmospheric oxygen acts as a shield and renders foil substantially corrosion resistant. Aluminium is also resistant to substances in the pH range 4 to 9.

Reflectivity: Reflects approximately 98% of radiant heat and light. There is no difference between the reflectivity of a bright and a matte foil surface.

Surface finish: The foil rolling process creates a highly polished finish. To produce thin foil economically, however, two layers are normally rolled together and then separated, the ‘inner’ surfaces taking on a matte finish. The thickness below which double rolling is done (typically about 50µm) varies according to the individual manufacturer. Single rolled aluminium foil can also be made in thinner gauges and produces a bright finish on both sides. A variety of embossed or textured surface finishes can also be produced.


Density 2.7 Alufoil specific weight 6.35 µm foil weighs 17.2 g/m2 Melting point 660°C Electrical conductivity 64.94% IACS (IACS: International Annealed Copper Standard) Electrical resistivity 26.5 nOm Thermal conductivity 235 W/m K Thickness Foil is defined as measuring less than 0.2mm (<200 µm)

What is Mylar®?
Mylar is often used to generically refer to polyester film or plastic sheet. However, it is a registered trademark owned by Dupont Tejjin Films for a specific family of plastic sheet products made from the resin Polyethylene Terephthalate (PET). The true generic term for this material is Polyester Film or Plastic Sheet.

Polyester Film/Plastic Sheet is manufactured in a range of different styles, finishes and thicknesses. Learn more information on the types of Mylar® that are available.


Mylar is a brand name material from Dupont. A light weight plastic that resists swelling or shrinking in normal temperatures and humidity.


The material doesn&#8217;t change with the temperature and humidity. A drawing can be printed on the material and the dimensions will be accurate. No matter if the dimension is specifically stated or not. The material is flexible and semi-transparent. Which allows for laying out contour surfaces.
 
TaoWolf

TaoWolf

Active Member
Fuzzbutter said:
Well I know that this is wrong simply because mylar has no metal, so it can't be plastic with an aluminum coating....

bigv1976:: Thank you, that really explained everything a lot more clearly for me :)
Click to expand...
Oh and you are right, Mylar plastic contains no metal. But is coated with a metal like aluminum or gold for reflectivity purposes in growing.
 
Spanishfly

Spanishfly

Well-Known Member
TaoWolf said:
Don't tell other people this, but aluminum foil is ~97% reflective.
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You are absolutely right, Taowolf. Aluminium is a highly efficient reflector, whether as a foil or as the coating on the mirror of my Maksutov-Cassegrain astronomical telescope. Scientists are agreed with this, and universally use aluminium as a reflector in telescopes and other optical instruments.

Lots of kids in this forum who are just repeating the BS that they have read will say otherwise, however
- like bigv above.
 
GreenNerd420

GreenNerd420

Active Member
Just get the emergency blankets from Walmart. They are made of mylar and sold for a buck for a 4' x 8' sheet. It's not that expensive...
 
Brick Top

Brick Top

New Member
Light reflection for plant growth involves more than just reflection. You have to consider light diffusion. You also have to consider if all light spectrum rays are equally reflected or not. When you do that you find that aluminum foil makes a poor reflective material for growing plants.

Some growers confuse the light reflection percentage of a reflective material as being the only way to gauge if it is a good choice or not. What people need to consider is if the material is highly efficient at specular or diffuse reflection of light. A mirror is extremely reflective but it is specular reflection and specular reflection is not good when it comes to growing. Diffuse reflection is what is important in growing. You cannot look only at percentage of reflectivity.

Reflection for plant growing goes beyond just bouncing light rays off a surface. You need an equal diffusion, an equal distribution of not only light rays as seen by the human eye but also those of the different color spectrum that plants need that the human eye is less sensitive to. Some materials that are highly reflective to light rays the human eye is most sensitive too will absorb a percentage of other light spectrum rays.

Another thing to consider about aluminum foil is that not all aluminum foil is made from the same grade aluminum. High grade aluminum will reflect more light than low grade aluminum. It is just like high grade or low grade reflective hoods. Just because each is made of aluminum does not mean they are equally reflective or equally efficient at reflectivity of light.

If someone wants the most success possible they should not look for ways to save a nickle here and a penny there on things that are important. If someone sticks with known high grade reflective materials they will always be better off than going the ghetto grow route.
 
bigv1976

bigv1976

Well-Known Member
Brick top you dont know shit you noob!!!! Hey buddy!! Did you notice my Brick Top post plagerism earlier in the thread?
 
Fuzzbutter

Fuzzbutter

Active Member
Spanishfly said:
Oh FGS, where do these dopey kids come from?? Green Nerd is an absolutely correct description, IMHO.

A to Z of materials - read the entry for aluminium foil - 98% reflectivity. TaoWolf you are TOTALLY correct .

http://www.azom.com/details.asp?ArticleID=1435#_Technical_Properties
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Pure aluminum foil yes, would be that reflective. The crap you buy in the supermarket and hence what I was referring to only has 50-65% light reflection. This is what I read from about 5 different science horti sites. Just because you can read and post a single site doesn't mean you're right. Also, ToaWolf is INCORRECT since mylar DOES NOT contain any metal and hence does not have simply "an aluminum" coating.
 
Fuzzbutter

Fuzzbutter

Active Member
TaoWolf said:
Don't take my word for it, but the myth that aluminium foil is poorly reflective only travels around in growing circles. In scientific and industrial use, it's properties are well known:
Click to expand...
Well yes, but the quality of reflection of high grade foil vs low grade (grocery store) foil comes into play as well. The foil I'm referring to is the cheap stuff from the grocers. High grade aluminum foil no question seems like it would be a very good bet.
 
TaoWolf

TaoWolf

Active Member
If anyone wants to cite an impartial source (not things like marketing claims, wiki, or forum quotes) that backs up claims that the aluminum used to make sheets is any different than the aluminum that is attached to plastic sheeting patented as the product called "Mylar" - go for it.
 
Brick Top

Brick Top

New Member
bigv1976 said:
Brick top you dont know shit you noob!!!! Hey buddy!! Did you notice my Brick Top post plagerism earlier in the thread?
Click to expand...

So what you are attempting to claim is when facts are copied at pasted rather than someone taking the time to reword them, and in the process risk not remaining factual, or to shorten and simplify something and save time, portions of factual pieces of information are used, that doing so somehow magically and mystically transforms facts into being incorrect? If you believe that you are irrational.

If you prefer to refuse to accept facts that is totally cool and the gang with me but it is irresponsible for you to attempt to influence others too do the same. If you are happy with what you do and believe then stick with it but if you convince others too do the same you will keep them from ever being as successful as they otherwise could be.

Do you really believe that if someone calls someone else a noob who is not one, that it magically and mystically transforms them into a noob? If so, you are irrational. Let's do a little test and see if calling someone a noob who is not one actually works or not. You are a noob. OK, did that somehow make you a noob? If not, why not? Do you believe it only works when you say it? If so, you are irrational.

I started growing in 1972 and nothing you can ever say will be capable of changing that.
 
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