# Glass: What do I need to know?



## glopal (Jun 18, 2008)

I've decide to compartmentalize my light from the rest of the box with a piece of glass, and give it some independant ventilation.

Now I know the glass should be tempered (why though?), anything else I should know about glass before I go and get a piece. 

How would a piece of glass effect the plants?


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## ChatNoir (Jun 18, 2008)

Each type of glass absorbs certain amount of light. In return, glass gets heated and eventually break down. There are some types of glass, resistant to heat, some times of glass that has more permeability than others. You should find a good glass that has both also do not absorb necessary partitions of light.

When it comes to lumens, permeability and the quality, you must think thrice before buying glass.


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## screwdriver (Jun 18, 2008)

I ask what type of light, what distance does glass need to span, why not cool tube?

You can get borosilicate glass sheets from Mcmaster.com.  My pyrex bread mold takes the heat of a 250w HPS.  I know someone that has a 400w HPS in one.

The glass doesn't need to be tempered.


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## 4u2sm0ke (Jun 19, 2008)

I used non tempered and it shatters with in 6 hrs from the heat..I run 1000 hps..I purchased tempered glass and have not had it brake yet...it reflex the heat while allowing light to travel threw..I lose a few lumes but gain it budd size..and not burning my girls..just my .2   KEEP M GREEN


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## HMGanja (Jun 19, 2008)

All pyrex(tempered) glass has been annealed and there-fore will not break from being heated up and then cooled rapidly.  Like the bake-a-rounds in the oven then taking them out.  And your light, from it being on 18hr then you turn it off and it cools quick.  You will HAVE to use tempered glass if its anywhere near the bulb.  Some may have gotten away with it with less watts, but its not worth the chance to me.


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## Hick (Jun 19, 2008)

4u2smoke said:
			
		

> I used non tempered and it shatters with in 6 hrs from the heat..I run 1000 hps..I purchased tempered glass and have not had it brake yet...it reflex the heat while allowing light to travel threw..I lose a few lumes but gain it budd size..and not burning my girls..just my .2   KEEP M GREEN


been there.. done that.. got the T-shirt..


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## HMGanja (Jun 20, 2008)

Hick said:
			
		

> been there.. done that.. got the T-shirt..


 
Ha!  I can imagine you guys faces when your just sittin on the couch or whatever then.......SHATTER....running to the grow room


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## Hick (Jun 20, 2008)

HMGanja said:
			
		

> Ha!  I can imagine you guys faces when your just sittin on the couch or whatever then.......SHATTER....running to the grow room


.. hee hee, I actually had my "suspicions" when I put the non-tempered in the 1k. Soooo, I gave it a 'test run' with no plants in the room.    Less than 1 hour to shatter it


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## 4u2sm0ke (Jun 20, 2008)

yeah that^^^^^  me too Hick..but then purchased 3/8 inch tempered and has been a success...I too did not have plants in..I was working on my setup at the time and did not know regular glass would shatter like that...mayB I should have asked here first..lol..


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## Hick (Jun 20, 2008)

4u2smoke said:
			
		

> yeah that^^^^^  me too Hick..but then purchased 3/8 inch tempered and has been a success...I too did not have plants in..I was working on my setup at the time and did not know regular glass would shatter like that...mayB I should have asked here first..lol..


..DITTO"..


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## 4u2sm0ke (Jun 20, 2008)

HMGanja said:
			
		

> Ha! I can imagine you guys faces when your just sittin on the couch or whatever then.......SHATTER....running to the grow room


 


:rofl: ..it was more like.. ..:bolt:..:fid: ....


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## The Hemp Goddess (Jun 20, 2008)

screwdriver said:
			
		

> I ask what type of light, what distance does glass need to span, why not cool tube?
> 
> You can get borosilicate glass sheets from Mcmaster.com.  My pyrex bread mold takes the heat of a 250w HPS.  I know someone that has a 400w HPS in one.
> 
> The glass doesn't need to be tempered.



Your Pyrex Bake Around is tempered glass.  Although I have read that HPS lights do not need tempered glass and MH do, I put tempered glass in all my reflector hoods.  As a person who ran through a plate glass door before the days of tempered glass (400 or so stiches), I cannot even begin to imagine how badly you could be hurt if your reflector glass exploded while you were in the room...


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## 4u2sm0ke (Jun 20, 2008)

The Hemp Goddess said:
			
		

> Your Pyrex Bake Around is tempered glass. Although I have read that HPS lights do not need tempered glass and MH do, I put tempered glass in all my reflector hoods. As a person who ran through a plate glass door before the days of tempered glass (400 or so stiches), I cannot even begin to imagine how badly you could be hurt if your reflector glass exploded while you were in the room...


 

Not to mention the fire hazard if you wernt in the room...( if glass Broke and then Broke light bulb...WOW ).and Hemp...I have Both 1000 HD and HPS and they Both are extremley HOT..KEEP M GREEN


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## screwdriver (Jun 20, 2008)

So I guess you can cut tempered glass.

Semantics?  Tempered, to me, is when glass would shatter into hundreds of pieces when fractured.  I think it is when glass is heated then rapidly cooled.  How rapidly, idk.  What I do know is that a bake around tube can be cut without it shattering. 

Glass exploding from heat? I'm still thinking about that.

I have no experience with hurricane lamp shades, but I believe those to be "ordinary" glass.  I also read people having success with those, but I don't know what watt light is being used.

Not enough info in the original post to say that tempered is needed.  Silly to put tempered glass in a small cabinet with cfls unless you think you are going to put your hand through it changing bulbs.  While I have never tried this, I am confident that ordinary glass would work with a 70w mh in my cabinet with no fear of it exploding.

4u2smoke, 3/8 tempered is what you are using?  Why so thick? Are you spanning a distance in feet?  Alot of energy being absorbed there for sure.


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## 4u2sm0ke (Jun 20, 2008)

hey screwdriver...3/8 is overkill but but figured for the price it was better...IDK..Glass exploding from heat...when my 1000 HPS regular glass broke I found pieces on top of my reflector...IDK any other way to explain it..

I should have asked what size light at the get go..when I was putting my area together is when I learned about glass to help aid in heat...i used regular 1/4 inch..then 3/8 temper...I am able to get my 1k with in 10 inches of cannopy...with glass...without..sure to set fire to top..IMO..

KEEP M GREEN


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## The Hemp Goddess (Jun 21, 2008)

4u2smoke said:
			
		

> hey screwdriver...3/8 is overkill but but figured for the price it was better...IDK..Glass exploding from heat...when my 1000 HPS regular glass broke I found pieces on top of my reflector...IDK any other way to explain it..
> 
> I should have asked what size light at the get go..when I was putting my area together is when I learned about glass to help aid in heat...i used regular 1/4 inch..then 3/8 temper...I am able to get my 1k with in 10 inches of cannopy...with glass...without..sure to set fire to top..IMO..
> 
> KEEP M GREEN



I have always used a sealed reflector that I air cool--I cannot keep my temps in line otherwise.  I can keep my plants about 6" away from the light, although I usually go about 10", too.  Sometimes I have to be away for several days at a time and I have had the bud grow to the glass and burn when at 6" (I want to be the one burning the buds, not the light).

Anything I have ever read anywhere says that you must use tempered glass for MH lights and while not required for HPS, it was recommended.  I bought a piece mof custom cut tempered glass almost 2' square and had it shipped to me for a little over $50--way less than a trip to the Doc in a Box for stitches should your untempered glass break while you are in the room...


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