# Reflection.



## HippyInEngland (May 30, 2009)

Aluminium 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 aluminium tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable

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 and 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: 

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. 

Elastomere paint.

A rubberised roofing paint with 90% reflection. Good for grow boxes. Mildew resistant. Highly reflective. 

Kool Seal White Elastomeric Roof Coating ~ $15.00 (1 Gallon) 

Ultra high reflectivity 
Forms a rubber-like blanket that expands and contracts 
Adheres to almost any surface (very good on wood and metal) 
Available @ Lowe's Home Improvement.

Want cheap Mylar?

The cheapest Mylar around-- only 2$ You save 18$ a roll! 

Its a Christmas present wrapping Mylar called Polywrap 

- Waterproof 
- 50 square ft. a roll 
0. 1 mil ( .001 inch) thick X 3 ft. wide X 20ft long. 

Note: Only buy the very Bright and shiny Mylar-type wrapping!

eace:


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## wmmeyer (May 30, 2009)

Good Post, HIE.  Thanks for sharing all that info.


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## SPEARCHUCKER (May 30, 2009)

Good stuff HIE.

I wonder what the reflective ability of that Chrome Spray Paint is. Seems like it would be up there with a few of those.


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## StoneyBud (May 30, 2009)

SPEARCHUCKER said:
			
		

> Good stuff HIE.
> 
> I wonder what the reflective ability of that Chrome Spray Paint is. Seems like it would be up there with a few of those.


What the human eye sees isn't what is brightest to plants. As Hippy said, the highly reflective *looking* glossy paints are really only slightly reflective.

As are most household mirrors.

The spectrum of light that's reflected is the big issue. Different types of materials reflect different spectrum's and absorb others.

Here's a note on the flat white paint; I use it in all my grow rooms. The plants grow faster near the wall than they do in the center, directly under the lights.


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## SPEARCHUCKER (May 30, 2009)

Thanks Stoney.
I was thinking chrome. Cause thats whats used in alot of flashlights, photographers flash equipment and such.

Did a little hunting. Cant find what band it reflects and doesnt. I thought it would just do full band. What ever hits it bounces off.


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## SPEARCHUCKER (May 30, 2009)

Found this little tidbit.




Now, for the first image [fig. 2.1] I've added a panoramic HDR image to the environment with spherical mapping, note how the HDR's luminance values gets adapted in a very nice way in the red sphere vs the chrome sphere. Note that the kitchen windows in the chrome sphere are blown out [fig. 2.1.2] with corresponding glare recorded at that exposure with the camera - while in the red sphere you can see the tree outside the window [fig. 2.1.1]. This is possible due to the fact that the luminance values have been scaled appropriately considering the strength of the reflections, the chrome sphere which is 100% reflective reflects the HDR image at the full strength of which it is set to render at but the red sphere which has maybe 5% of reflectivity at that spot brings down the HDR image to representative values.

But thats for regular polished chrome.
I dont know. Just tossing ideas.


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## Caretaker (May 30, 2009)

For how much trouble foil is and how its at the bottom of the list for reflection it is so not worth it. I started with doing that. It cost more money and takes more time and also reflects less to mess with that than to just paint the walls white. It took me ten minutes a coat for a 6x4 room. Better than laying down the tape then lining the walls with the foil and hoping it doesnt rip. Then with the fans blowing it can gets loud if the foil is waving in the wind.


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## StoneyBud (May 31, 2009)

SPEARCHUCKER said:
			
		

> Found this little tidbit.
> 
> View attachment 116114
> 
> ...


You're confusing what the human eye sees as light and what plants use as light. The two have very little in common.

Plant usable lumens are what you're after. The types of reflective material that Hippy pointed out in his first post are what you should stick to for a proven method in growing weed.

The flat white paint has always been my favorite for it's ease of use and durability.

I use BEHR Premium Plus Interior Flat "Ultra Pure White" Number 1050.

As I said earlier, the plants closest to the wall grow faster than those that are directly beneath the lights.


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## The Effen Gee (May 31, 2009)

Fylon is the best I have used. 

Expensive, but the best.


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