Aluminum Foil

[bombbudpuffa]

I've used al foil before with good results. I don't have a clue about the hot spots thing but seems like Rockster has done his homework. With that said, I wouldn't switch back to al foil from my mylar and radiant barrier.

 

[Rockster]

You saw a spot of light focused 2 feet from the lamp?

Well I never,ha ha!

So was this an imperfection or part of the design HippyInEngland?

I'm still scratching my head here as if it was on the end it would shine on your growroom wall unless you had your lamps hanging vertically?

 

[84VW]

I've used al foil before with good results. I don't have a clue about the hot spots thing but seems like Rockster has done his homework. With that said, I wouldn't switch back to al foil from my mylar and radiant barrier.

I'll bet at-least half of us have tried/used aluminum foil with fine results(myself included)

then i went to flat white then to Mylar...I'll take mylar any day, or flat-white until i can get more Mylar

i will never use foil again

 

[leafminer]

'Hot spots' do not exist within a growroom and are certainly not caused by ali foil.

Heat can travel by means of three ways,conduction,which is heat passing through a material.

If you heat a piece of copper held in your hand the heat conducts along its length and you drop it as it becomes hot.

Radiation,which is the warmth you feel from the heat energy directly radiated from the lamp and requires no medium to carry it.

And convection,which is heat being transferred from place to place within a body of air or other gas.

Radiation cannot 'collect' in an area so that can't cause hot spots.It heats the ali foil but the foil has little mass so what is absorbed is conducted away by what its mounted on be it a wall or panel board of a cupboard etc.

Conduction cannot cause hot spots as ali foil doesnt conduct a lot of heat as there isnt much mass to it.

Convection or rather poor convection from too little vent can cause hot air to stratify in a layer at the top of the growroom and is the closest thing to a 'hot spot' in a grow.

Also,poor reflectors make hot spots of a kind as there is a concentration of heat and light energy usually directly beneath it which is why diffusers are used which are designed to be situated right in that 'hot spot'.

So the ali foil thing is a grow myth I'm afraid.It's not the best reflective material to use but is quite adequate and does not cause stretching due to these mythical zones called hot spots.

A scientist or engineer! Good. Makes sense.
Yeah. I have got hot spots but they are from my lamps, the reflectors produce a beam in the centre that burns leaves as much as 4ft away. Like Rockster said, I am going to have to make a diffuser to fix that. I'll probably make a pair of cones 3" diameter, one for each light, covered with Mylar, and fix them in the centre using thin wires.