Gastanker
Well-Known Member
I personally am not keen on posting this information as this silly myth is so wise spread and rampant on this site that I'll probably just receive a bunch of flack from people who have never seriously looked into the issue. Unfortunately for me I have been pressured to post this so here it is. Of course, feel free to change my mind but if you want to say anything contrary please have something to back it up with. I should mention that I was a big foil hater and huge white paint enthusiast before being presented with actual data on an aquarium site - never seen actual data on any pot growing sites.
1 - Aluminum foil does NOT create hot spots that can burn your plants.
2 - Aluminum foil is more reflective than emergency blankets and many white paints.
3 - Aluminum foil does not increases heat in a vented enclosure and can actually lower it over white paint.
Lets cover 1 first - this has got to be the silliest rumor of them all as I guarantee you no one has ever seen a plant burned by aluminum foil. The generally accepted ranking of reflective surfaces is thus - Polished aluminum, closely backed mylar, aluminum foil, white paint. This is the generally accepted ranking based on many many light related forums (indoor gardening, aquarium... not just RIU) If polished aluminum is more reflective than foil then why would a dimple in polished aluminum not burn a plant? Why wouldn't a dimple in mylar burn a plant?
The thought behind foil burning plants is that it wrinkles easily and that a tiny tiny wrinkle can focus enough reflected heat that the heat burns the plant. So if you take the same small wrinkle in foil and create it in mylar (which reflects more heat than foil) then the mylar would burn the plant even more - same applies to polished aluminum. I keep my dimpled polished aluminum reflector 4" from my plants... Wouldn't a dimple ~6" from my plant and 2" from my bulb focus more light than a dimple in foil several feet from the bulb? Why doesn't my light burn all of my plants? This is super super simple people. Hell mylar creates large parabolic dimples more often than foil - a larger parabolic dimple in mylar would reflect far far more heat onto a single small spot than foil could ever accomplish.
I personally created a large parabolic dish out of foil in attempts to burn a plant and had no success.
#2 - here no one will believe me as I've lost my PAR photos but here is some food for thought - (I appologize about the bolding)
Again, I was a huge hater of foil and argued the same points. I ended up getting really frustrated on a fish tank forum trying to convince people that white paint and mylar was better, so I performed all of these tests and to my surprise foil actually works really well.
I tested 5 different surface types, titanium white paint, aluminum foil, dimpled polished aluminum, mylar, and plain white paper (the squares all fit into the reflector to create the same angle). They all reflect differently but in order of maximum mm PAR directly under the bulb it went polished aluminum, backed mylar, aluminum foil, white paint, white paper. White paint and foil were very close and I would not be surprised, like I have seen others to show, that some white paint is more reflective than foil but it is very close.
Few of my tests on the importance of closely backing mylar (it blows otherwise) Foil does not need to be backed - no light shows through
Light in reflector:
Light with a piece of white paper on top:
Light with a sheet of mylar with no backing:
mylar with the same sheet of paper backing it:
Mylar is terrible with no backing. But backed by just a piece of white paper and no light comes through even though the light had no problem going through the paper.
Now white paint:
Tried to put it on nice and thick:
Not to great:
1/4 just paper, 1/4 with white paint, 1/4 with white paint and mylar, 1/4 with just mylar:
Notice along the edge of the mylar where it isn't flat up against the paper? Light goes through it and the paper. But when right up against backing nothing escapes.
/e I'm putting two more coats of white paint and will test again. I'm disappointed it didn't work better as I use white paint often.
Three thick coats of titanium white paint (one of the more reflective whites)
Compared to just the paper:
The two compared to mylar:
Space blankets are reflective but have such a thin coating of aluminum that they just don't compare to the rest of the reflective surfaces.
#3 - Foil is used in cooking because it reflects heat. By reflecting heat foil ensures that your food is evenly cooked at the ambient temps versus unevenly cooked by directional radiant heat. If you measure a white wall with an infrared thermometer it will be considerably warmer than the same wall with a piece of aluminum foil on it as the foil reflects the heat that the wall would otherwise absorb. Foil acts the exact same heat wise as mylar: If you line your grow room in foil the foil will reflect the majority of the heat back into the room versus letting it be absorbed by the walls; This can be good and bad: if you do not vent your room the air temps will get very very hot (bad). If you have thin white walls they can act as a heat sync in which case foil wouldn't help you much temperature wise. However, if you have thick walls and do vent your room you can keep room temps lower with foil than with white paint - heat is retained in the air temps which is quickly vented off and the walls which normally would act as a heat bank are shielded from the IR - All of this applies to mylar vs white paint in the same way.
I am in no way saying that foil is the best product nor saying everyone should use it but people need to stop bullying newer growers when they have no idea what they are talking about. Foil is easy to use, very reflective, and works better than most other readily available reflective materials. There is no need to go purchase a see through space blanket when you have foil lying around. and silver wrapping paper created to diffract the light into tiny rainbows is most definitely not more advantageous. Hopefully I'll find my PAR test result pics or another one from one of the many aquarium sites who have performed the same tests.
And just an FYI. Foil reflects UV whereas white paint does not. And I should mention that I have nothing to gain by this - I use mylar, pandafilm, and white paint.
1 - Aluminum foil does NOT create hot spots that can burn your plants.
2 - Aluminum foil is more reflective than emergency blankets and many white paints.
3 - Aluminum foil does not increases heat in a vented enclosure and can actually lower it over white paint.
Lets cover 1 first - this has got to be the silliest rumor of them all as I guarantee you no one has ever seen a plant burned by aluminum foil. The generally accepted ranking of reflective surfaces is thus - Polished aluminum, closely backed mylar, aluminum foil, white paint. This is the generally accepted ranking based on many many light related forums (indoor gardening, aquarium... not just RIU) If polished aluminum is more reflective than foil then why would a dimple in polished aluminum not burn a plant? Why wouldn't a dimple in mylar burn a plant?
The thought behind foil burning plants is that it wrinkles easily and that a tiny tiny wrinkle can focus enough reflected heat that the heat burns the plant. So if you take the same small wrinkle in foil and create it in mylar (which reflects more heat than foil) then the mylar would burn the plant even more - same applies to polished aluminum. I keep my dimpled polished aluminum reflector 4" from my plants... Wouldn't a dimple ~6" from my plant and 2" from my bulb focus more light than a dimple in foil several feet from the bulb? Why doesn't my light burn all of my plants? This is super super simple people. Hell mylar creates large parabolic dimples more often than foil - a larger parabolic dimple in mylar would reflect far far more heat onto a single small spot than foil could ever accomplish.
I personally created a large parabolic dish out of foil in attempts to burn a plant and had no success.
#2 - here no one will believe me as I've lost my PAR photos but here is some food for thought - (I appologize about the bolding)
Again, I was a huge hater of foil and argued the same points. I ended up getting really frustrated on a fish tank forum trying to convince people that white paint and mylar was better, so I performed all of these tests and to my surprise foil actually works really well.
I tested 5 different surface types, titanium white paint, aluminum foil, dimpled polished aluminum, mylar, and plain white paper (the squares all fit into the reflector to create the same angle). They all reflect differently but in order of maximum mm PAR directly under the bulb it went polished aluminum, backed mylar, aluminum foil, white paint, white paper. White paint and foil were very close and I would not be surprised, like I have seen others to show, that some white paint is more reflective than foil but it is very close.
Few of my tests on the importance of closely backing mylar (it blows otherwise) Foil does not need to be backed - no light shows through
Light in reflector:
Light with a piece of white paper on top:
Light with a sheet of mylar with no backing:
mylar with the same sheet of paper backing it:
Mylar is terrible with no backing. But backed by just a piece of white paper and no light comes through even though the light had no problem going through the paper.
Now white paint:
Tried to put it on nice and thick:
Not to great:
1/4 just paper, 1/4 with white paint, 1/4 with white paint and mylar, 1/4 with just mylar:
Notice along the edge of the mylar where it isn't flat up against the paper? Light goes through it and the paper. But when right up against backing nothing escapes.
/e I'm putting two more coats of white paint and will test again. I'm disappointed it didn't work better as I use white paint often.
Three thick coats of titanium white paint (one of the more reflective whites)
Compared to just the paper:
The two compared to mylar:
Space blankets are reflective but have such a thin coating of aluminum that they just don't compare to the rest of the reflective surfaces.
#3 - Foil is used in cooking because it reflects heat. By reflecting heat foil ensures that your food is evenly cooked at the ambient temps versus unevenly cooked by directional radiant heat. If you measure a white wall with an infrared thermometer it will be considerably warmer than the same wall with a piece of aluminum foil on it as the foil reflects the heat that the wall would otherwise absorb. Foil acts the exact same heat wise as mylar: If you line your grow room in foil the foil will reflect the majority of the heat back into the room versus letting it be absorbed by the walls; This can be good and bad: if you do not vent your room the air temps will get very very hot (bad). If you have thin white walls they can act as a heat sync in which case foil wouldn't help you much temperature wise. However, if you have thick walls and do vent your room you can keep room temps lower with foil than with white paint - heat is retained in the air temps which is quickly vented off and the walls which normally would act as a heat bank are shielded from the IR - All of this applies to mylar vs white paint in the same way.
I am in no way saying that foil is the best product nor saying everyone should use it but people need to stop bullying newer growers when they have no idea what they are talking about. Foil is easy to use, very reflective, and works better than most other readily available reflective materials. There is no need to go purchase a see through space blanket when you have foil lying around. and silver wrapping paper created to diffract the light into tiny rainbows is most definitely not more advantageous. Hopefully I'll find my PAR test result pics or another one from one of the many aquarium sites who have performed the same tests.
And just an FYI. Foil reflects UV whereas white paint does not. And I should mention that I have nothing to gain by this - I use mylar, pandafilm, and white paint.
