More light

[dcarch]

I bought from HD a roll of aluminum foil self-adhesive tape. I don't remember how much, may be $6. I think the tape is used for vapor barrier insulation use. I taped on the white reflectors of my fluorescent fixtures. I am getting a lot more light now.

Some of you use kitchen foil, but this is a lot neater and perminent job.

There are two kinds of tape they sell. One has red markings on the tape. The markings come off easily with acedtone.

dcarch

[Worth1]

For those that want or care to know white reflects more light than foil.

Worth

[Suze]

Originally Posted by Worth1

For those that want or care to know white reflects more light than foil.

I thought "it depends" [upon the type of white surface (glossy or flat), and the type of metal/foil/aluminum surface (sounds like foil might let light through)]. The explanation in the post below is a fairly good example of what I am referring to. I am also including it because I think dcarch might find it interesting.

In my opinion and experience, for the purpose of growing seedings for transplant, it just does not matter all that much whether one uses white or foil/aluminum reflectors.

RE: Rebuilding My Seedling Shelves/Lights - Suggestions?

* Posted by shrubs_n_bulbs z8/9 UK (My Page) on
Thu, Jan 4, 07 at 14:51

actually white is better than mirrors or aluminum

Actually that's not true. Aluminium has a reflectivity around 90%. Aluminium reflectors are the most robust and efficient solution but they are also quite expensive and must be kept clean and free from corrosion (salt from sea air or repeated condensation causes a white bloom which reduces the reflectivity). Aluminium foil, cooking grade, is too thin and lets around half the light straight through so don't use that. Mylar has a reflectivity around 95% but can be difficult to use, easy to damage, and it is flammable! Normal back-surface mirrors have a reflectivity around 90% but are not good for plant reflectors because the light is reflected "like a mirror", it will either miss your plants or hit them in a focussed way which will be damaging. White paint has a reflectivity up to about 90% but usually more like 80%. Some are lower, choose something like a latex roofing paint, or just use indoor flat matt paint, you can always repaint frequently. Avoid oil-based "gloss" paints, reflectivity is significantly lower and they fade very quickly under intense light. Visqueen has a reflectivity of 85%, some of the hanging and durability problems of mylar, I haven't had the opportunity to try burning it, I imagine it would certainly melt and possibly burn with a noxious smoke.

I use flat white paint on all surfaces around my plants, it is nearly as effective as other solutions and better than some, cheaper, and much more convenient. An aluminium reflector just above fluorescent tubes or HID bulbs is helpful because the extra few percent efficiency makes a difference with the really intense light there.

[Worth1]

Suze,
It is only about 3% more light for the white surface, not enough to amount a hill of beans.
There is a great site for indoor growing but I won’t post it as it has to do with ANOTHER popular plant that folks like to grow.

The sad part is it has a lot of useful information that can be cross referenced to starting tomatoes indoors and then planting outside or growing in side.

I edited some of the information here so as not to offend anyone.
I hope I got it all!!!
NO I don’t grow the stuff!!!!!
PM me if anyone wants the link these guys no more about container growing and indoor growing than anyone I know.

Worth


Chapter Five
ARTIFICIAL LIGHT[
5.2 Fixtures
Florescent light is the most effective and efficient source of artificial light readily available to the home grower. Florescent lamps are the long tubes typical of institutional lighting. They require a fixture which contains the lamp sockets and a ballast (transformer) which works on ordinary house current.
Tubes and their fixtures come in length from four inches to 12 feet. The most common and suitable are four- and eight-foot lengths. Smaller tubes emit too little light for vigorous growth; longer tubes are unwieldy and hard to find. The growing area must be large enough to accommodate one or more of these fixtures through a height of at least six feet as the plants grow. Fixtures may hold from one to six tubes and may include a reflector, used for directing more light to the plants. Some fixtures are built with holes in the reflectors in order for heat to escape. They are helpful in areas where heat builds up quickly. You can make reflectors with household materials for fixtures not equipped with reflectors. Try to get fixtures that have tubes spaced apart rather than close together. See 5.5 for further suggestions.
The tubes and their appropriate fixtures are available at several different wattage or outputs. Standard or regular output tubes use about 10 watts for each foot of their length - a four-foot tube has about 40 watts and an eight-foot tube about 80 watts.
High Output (HO) tubes use about 50 percent more watts per length than regular output tubes and emit about 40 percent more light. An eight-foot (HO) runs on 112 to 118 watts. Very High Output (VHO) or Super High Output (SHO) tubes emit about two-and-a-half times the light and use nearly three times the electricity (212 to 218 watts per eight-foot tube).
The amount of light you supply and the length of the tube determine the size of the garden. TOMATOES will grow with as little as 10 watts per square foot of growing area, but the more light you give the plants, the faster and larger they will grow. We recommend at least 20 watts per square foot. The minimum-size garden contains a four-foot fixture with two 40-watt tubes, which use a total of 80 watts. Dividing total watts by 20 (watts per square foot) gives 80w divided by 20w/sq. ft=four sq.ft. (an area one by four feet). A four-tube (80 watts each) eight-foot fixture would give: 320w divided by 20w/sq. ft. = 16 sq. ft. or an area the length of the tube and about two feet wide.
VHO and HO tubes in practice don't illuminate as wide an area when the plants are young, because the light source is one or two tubes rather than a bank. Once the plants are growing well and the light system is raised higher, they will illuminate a wider area. Figure about 25 w/(ft*ft) for HO and 35 w/(ft*ft (or foot squared)) for VHO to determine garden size. A two-tube, eight-foot VHO fixture will light an area the length of the tube and one-and-a-half feet wide.
The more light you give the plants, the faster they will grow. Near 50w/sq. ft. a point of diminishing returns is reached, and the yield of the garden is then limited by the space the plants have to grow. For maximum use of electricity and space, about 40w/sq. ft. is the highest advisable. Under this much light the growth rate is incredible. More than one grower has said they can hear the plants growing - the leaves rustle as growth changes their position. In our experience, standard-output tubes can work as well as or better than VHO's if four or more eight-food tubes are used in the garden.
The yield of the garden is difficult to compute because of all the variable that determine growth rate.

5.3 Sources
When sunlight is refracted by raindrops, the light is separated according to wavelengths with the characteristic colours forming a rainbow. Similarly, the white light of electric lights consists of all the colours of the visible spectrum. Electric lights differ in the amount of light they generate in each of the colour bands. This gives them their characteristic colour tone or degree of whiteness.
Plants appear green because they absorb more light near the ends of the visible spectrum (red and blue) and reflect and transmit more light in the middle of the spectrum (green and yellow). The light energy absorbed is used to fuel photosynthesis. Almost any electric light will produce some growth, but for normal development the plants require a combination of red and blue light.
Sunlight has such a high intensity that it can saturate the plants in the blue and red bands, though most of the sun's energy is in the middle of the spectrum. Artificial lights operate at lower intensities; so the best lights for plant growth emit much of their light in the blue and red bands.
Fluorescent Tubes
Several lighting manufacturers make tubes (gro-tubes) the produce much of their light in the critical red and blue bans. (Plant-gro (GE), Gro-Lux (Sylvania), Agro-Lite (Westinghouse), and gro-lum (Norelco) are examples, and they look purple or pink. Vita-lite and Optima (Duro-test) produce a white light with a natural spectrum very similar to daylight. Duro-test blubs are more expensive than other tubes but they last twice as long. {See spectrum for "The action spectra of chlorosynthesis and photosynthesis compared to that of human vision. Adapted from IES Lighting Handbook237"}
Theoretically, these tubes should work better for growing plants than standard lighting tubes. However, some standard or regular fluorescent tubes used for lighting actually work better for growing plants than more expensive natural-spectrum tubes and gro-tubes specifically manufactured for plant growth. The reason is that regular fluorescent produce more light (lumens), and overall lumen output is more important for growth rate than a specific light spectrum. To compensate for their spectrums, use them in combinations of one "blue" fluorescent to each one or two "red" fluorescent (Box B).
Manufacturers use standardised names such as Daylight and Sofwhite to designate a tube that has a certain degree of whiteness. Each name corresponds to a tube that emits light in a particular combination of colour bands. For example, Cool White emits more blue light than other colours and appears blue-white. By combining tubes that emit more blue light with tubes that emit more red light, the tubes complement each other and produce a more natural spectrum for healthy plant growth. More "red light" than "blue light" sources are needed to foster healthy growth, so use two red tubes to each blue tube.
The best combinations are either Warm White or Soft White (red) tubes used with either Cool White or Daylight (blue) tubes. These four tube types are common, much cheaper, and when used in combination, will give you a better return than any of the more expensive gro-tubes or natural-spectrum tubes. Any hardware store carries these common lighting tubes, and the cost may be less than a dollar each.
Do not use tubes with "deluxe" in their designation. They have a more natural spectrum but emit considerably less light. Preferably, buy "Cool White" since it emits 50 percent more light than "Cool White Deluxe."

[dcarch]

Suze,

I am familiar with shrubs_n_bulbs , who is very knowledgeable in the topics of lighting, but I do disagree with him and some others in a few areas:

1. Aluminum reflects higher then 90%, that's why it’s used in almost all reflector applications, including astronomy mirrors.

2. This is an easy one: Go get yourself a piece of alum foil now and shine the brightest light you can find on it, including sunlight, you will not be able to see any light passing thru the foil. He/she is 100% wrong that 50% of the light passes thru the foil. Gold foil for artist's use yes. It's so thin you can see thru it.

3. Alum is one of the most corrosion resistant metal because it forms alum oxide immediately which protect its surface. Exterior building curtain walls last hundreds of years. It will not resist strong alkaloids very well however.

4. "Normal back-surface mirrors have a reflectivity around 90% but are not good for plant reflectors because the light is reflected "like a mirror", it will either miss your plants or hit them in a focussed way which will be damaging." is an incomplete statement and not a relevant statement most of the time. It applies mostly to a point source and poorly positioned or designed reflector. It does not apply to fluorescent lights at all.

5. White reflectors are much better then no reflectors. White, by the very definition, it reflects all colors in all directions therefore a lot of light will be lost in the directions which are not hitting your plants. The only time white reflectors are effective is when the surroundings are also all white which can reflect back the lost light. It may be misleading to perceive white to be more effective because you can see the bright white reflector and a good alum reflector appears to be very dark. The reason is that a good reflector should throw all the light where you want it to be and not on you.

With the desire to grow compact strong plants under light and with energy cost so high, it is very important to have the most efficient light source, the best focused and reflective reflector, and as much as possible a reflective environment.

I recommend the alum tape. BTW, I am not the owner of HD :wink:

dcarch

[garnetmoth]

Worth- thanks for that post about herbs, i mean tomatoes!

i just bought a 2nd 4' shop light, red and blue mid-line tubes (not gro-tubes) and hope to see results soon!

$100-300+ for fancy shelving units, or $9 for a shoplight. hurrah!

[landarc]

I have nothing to add about lighting, but, Garnetmoth, that is one heck of a tattoo. That must've been quite a sitting.

[Araness]

lol I'm trying to get a better view of that tat!

And heck I need to get the local home grown guy to come set up my lighting if he's as good as that guy I'm set!