# Ready to get blown



## Highbeam (Sep 29, 2010)

I did a remodel last year to a converted garage that included rigid foam on top of the old sloped garage floor and then a new level slab, new walls, sheetrock, bathroom, etc. It was a 25x25 space. It had old fiberglass batts above the flat ceiling that I was able to keep in place with string during the installation of a new ceiling. So this last weekend I went up and installed baffles in every rafter cavity leading to the enclosed soffit, sealed up every penetration with expanding foam and caulk, and finally built a plywood dam around the attic access hatch about 16" above the sheetrock. The old batts have settled to about 5" deep and the plan is to bring that up to an R-38 with blown in fiberglass. I have several issues with cellulose so don't use it. 

I got a bid for 503$ to add the additional insulation for the 625 SF. When the same company did the same job over the rest of the house they added 11" of fiberglass for a total depth of 16-17". Made a big difference.

I thought the price was pretty good especially when you take 30% credit from it. Trouble is they are 6 weeks out! I can wait.


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## vvvv (Sep 29, 2010)

Why not cellulose?


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## Highbeam (Sep 29, 2010)

~*~vvv~*~ said:
			
		

> Why not cellulose?



Because it's crap pook. Even the word cellulose should be enough to make you never want to use it. Those last three letters, OSE, ose is a sugar like sucrose, dextrose, lactose, fructose, etc. I do not want cotton candy in my attic. Sugar burns and is a food source. Then of course it is heavier too.


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## velvetfoot (Sep 29, 2010)

I went through this last November.  https://www.hearth.com/econtent/index.php/forums/viewthread/46010/

I paid $850/1000 ft2 for an additional R38, supposedly.  Close to your price per ft2.


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## vvvv (Sep 30, 2010)

Highbeam said:
			
		

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too late, 15yrs ago i blew in ~ 18" on top of fg batts which filled the voids nicely & has since settled some. i like the settling cause it minimizes airwash thru the looser fg.


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## allhandsworking (Sep 30, 2010)

Highbeam I think you are misinformed I'm a NYC firefighter I have been in dozens of structure fire were the only place fire traveled was in bays or pipe chases that didn't have cellulose!  After this real world experience I inquired about it for my 100 year old house without any insulation.  The contractor held a hand full of this material and aimed a blow torch at it, it did not burn!  It is also treated with boric acid, this makes it non palatable for insects he then proceeded to eat some( non toxic)!  Ok he was wanting the job!  I am not against fiberglass or foam just wanted to point out some facts!  Installation was easy clean and quick.  We save 50% on or heating bill!  Then we installed the wood insert and I said good buy to my oil man!


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## velvetfoot (Sep 30, 2010)

The guy that blew in the fiberglass said cellulose was dusty to blow and the he would've had to wear more of a mask.

With either of them though, I sure hope I never have to remove it!


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## GaryGary (Oct 3, 2010)

Hi,
One well documented problem with loose fill FG is that is develops convection currents within the insulation that get worse as the temperature goes down.  At cold temperatures it can cut the effective R value of FG in half.  So, just under the conditions you need it the most, it works half as well as it should.

This is the full scale NREL test that documents this problem:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html

and,
http://www.foam-tech.com/theory/rvaluedrift.htm

Cellulose does not have this problem, and has a good long track record of performing well.

Gary


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## Highbeam (Oct 4, 2010)

allhandsworking said:
			
		

> structure fire were the only place fire traveled was in bays or pipe chases that didn't have cellulose!  After this real world experience I inquired about it for my 100 year old house without any insulation.  The contractor held a hand full of this material and aimed a blow torch at it, it did not burn!  It is also treated with boric acid, this makes it non palatable for insects he then proceeded to eat some( non toxic)!  Ok he was wanting the job!  I am not against fiberglass or foam just wanted to point out some facts!  Installation was easy clean and quick.  We save 50% on or heating bill!  Then we installed the wood insert and I said good buy to my oil man!



You do realize that cellulose insulation is just ground up newspaper right? I propose that any type of insulation in those bays would have prevented fire transfer. The cellulose just happened to be the junk that was there acting as a fireblock.

That contractor was using street tricks on you. Paper burns, cotton candy dissolves in water, bugs eat it. Why bother with adding all these chemicals to ground up paper trying to cover up the shortcomings when fiberglass works so well? I sealed my ceiling penetrations so I am not using the blown in insulation as a vapor barrier. 

Cellulose does of course work, there are times when you have no choice such as when filling existing walls. If given the choice, I will always choose fiberglass.


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## vvvv (Oct 4, 2010)

Highbeam said:
			
		

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& u never retested ur old fridge during humid weather too. seems kinda close minded for an engineer? still, some get the degree so to land the job$= gotta be fire specs on cellulose, somewhere


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## Highbeam (Oct 4, 2010)

~*~vvv~*~ said:
			
		

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Take a flying leap pook. Fire specs for newspaper are based on treatment method, they allegedly spray something on the paper in hopes it won't burn. Some folks have open minds and some have already made a decision.


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## midwestcoast (Oct 4, 2010)

Highbeam said:
			
		

> Paper burns, cotton candy dissolves in water, bugs eat it. Why bother with adding all these chemicals to ground up paper trying to cover up the shortcomings when fiberglass works so well? I sealed my ceiling penetrations so I am not using the blown in insulation as a vapor barrier.
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> Cellulose does of course work, there are times when you have no choice such as when filling existing walls. If given the choice, I will always choose fiberglass.



No skin off my back what you go with & I think you'll be happy with a nice thick blanket of whatever up there, but I also think you're repeating unsubstantiated myths about cellulose.  I did my homework on fiberglass & cellulose before doing my attic and found:  There's a lot of industry junk-science out there, but a growing consensus that Borate treated cellulose is more protective against fire than fiberglass. Not only does it not burn, but the greater density can smother fires.  Why would insurance companies approve cellulose if their testing didn't show it to be fire-proof?
No evidence that Borate treated cellulose causes problems with bugs.
Sealing air-leaks is necessary for cellulose or FG to work properly, but it doesn't eliminate convective heat loss through blown fiberglass. The convective current is driven by the temp difference btwn the interior & exterior sides of the insulation. "ORNL researchers have determined that some types of blown-in insulation...permit air movement within the insulation, resulting in natural convection...The researchers confirmed that natural convective heat loss in some loosefill fiberglass insulations can be responsible for as much as half of the heat loss at very low temperatures." http://www.ornl.gov/info/ornlreview/rev25-34/chapter8sb2.htm  Unfortunately the effect becomes more significant the colder the exterior temp is.  The currents don't develop in cellulose due to greater density.


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## midwestcoast (Oct 4, 2010)

In Highbeams application, with rigid foam (thickness?) and FG batts (if paper-faced) below it, I'd expect convection within the blown fiberglass to be much reduced or eliminated as there wouldn't be the temp differential to drive it.


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## allhandsworking (Oct 5, 2010)

Highbeam said:
			
		

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. To each his own I would use Fiberglass in certain applications!


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## Highbeam (Oct 5, 2010)

midwestcoast said:
			
		

> In Highbeams application, with rigid foam (thickness?) and FG batts (if paper-faced) below it, I'd expect convection within the blown fiberglass to be much reduced or eliminated as there wouldn't be the temp differential to drive it.



Actually, the rigid foam is on the floor between two layers of concrete. R-10 2 inches thick. 

It's like this, there are drawbacks to each material (FG and paper) and I consider the paper to be inferior. I choose the synthetic material that is naturally non-burning, non-food, and non biodegradable for an out-of-site application where there could be fire, bugs, and water. If I had the paper in an existing space I would leave it be, I don't think that the drawbacks warrant removal. In some cases, the paper can be superior due to other qualities it has including flowability and the wet spray applications.


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## vvvv (Oct 5, 2010)

midwestcoast said:
			
		

> In Highbeams application, with rigid foam (thickness?) and FG batts (if paper-faced) below it, I'd expect convection within the blown fiberglass to be much reduced or eliminated as there wouldn't be the temp differential to drive it.


nor the wind required for attic ventilation?


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## vvvv (Oct 5, 2010)

theoretically, if u laid plastic over existing insulation, blew insulation on plastic, & then covered blown insulation with plastic the added insulation plastic sandwich would keep the insulation below from reaching the dew point ?  dependent on r value of sandwich= consult building science .com


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## Seasoned Oak (Oct 7, 2010)

Been insulating houses for 30 years. In my experience cellulose is far superior to fiberglass. Iv seen fiberglass shrink to half is original size after so many years in the walls ,also too many spaces around wire and electrical outlets,and odd sized joist spacings, my as well have nothing in the walls. WHen i tear out previously insulated walls sections its the fiberglass thats failed as you can tell by all the dirt in it from air infiltration,not the cellulose. If you gave me fiberglass for free i would not use it to insulate a house.


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## Reggie Dunlap (Oct 7, 2010)

Highbeam- 
I'm a builder in northern Vermont and we use blown cellulose frequently. While it has some drawbacks (settling) it is far superior to fiberglass when properly installed in flat ceilings. It will settle a little over time which is why I don't use it in walls. But in a flat ceiling application it is the best material per dollar spent. Only expanding urethane foam is better than cellulose, but foam is 3-4 times more expensive. We generally blow around 16 inches of cellulose and over a few years it settles out to around 14. It fills every nook and cranny, seals up the can lights, and it's inexpensive. There's a reason most every insulation contractor in the colder parts of the country uses cellulose.

Fiberglass is a good insulating material but even the most conscientious installer can't eliminate all the little gaps. It shrinks over time and it's nasty to work with.

As far as fire goes have you ever tried to burn cellulose? I have and whatever retardant they use is pretty effective.


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## Seasoned Oak (Oct 7, 2010)

Reggie Dunlap said:
			
		

> Highbeam-
> I'm a builder in northern Vermont and we use blown cellulose frequently. While it has some drawbacks (settling) it is far superior to fiberglass when properly installed in flat ceilings. It will settle a little over time which is why I don't use it in walls. But in a flat ceiling application it is the best material per dollar spent. Only expanding urethane foam is better than cellulose, but foam is 3-4 times more expensive. We generally blow around 16 inches of cellulose and over a few years it settles out to around 14. It fills every nook and cranny, seals up the can lights, and it's inexpensive. There's a reason most every insulation contractor in the colder parts of the country uses cellulose.
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> Fiberglass is a good insulating material but even the most conscientious installer can't eliminate all the little gaps. It shrinks over time and it's nasty to work with.
> ...


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If you blow the walls tight they dont settle. Iv torn out walls that were blown 10-15 years ago and NO settling ZERO.


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## kenny chaos (Oct 7, 2010)

Hey Pook-
Wouldn't the number of people with cellulose be directly proportional to the number
of people who live on fast food?  Not pretty, but good insulation.


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## vvvv (Oct 7, 2010)

& such would boost the service part of the economy


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## Highbeam (Oct 7, 2010)

Trump and reggie, this isn't the walls and this is blow in fiberglass so it doesn't get cut. The new blown in FG is "itchless" so it feels more like cotton. Cellulose truly does have some benefits. My favorites are the flowability and the resistance to air movement.


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## GaryGary (Oct 7, 2010)

Highbeam said:
			
		

> Trump and reggie, this isn't the walls and this is blow in fiberglass so it doesn't get cut. The new blown in FG is "itchless" so it feels more like cotton. Cellulose truly does have some benefits. My favorites are the flowability and the resistance to air movement.



My favorite cellulose advantage is that it does not lose half its R value under cold conditions -- that seems like an important feature in an insulating material 

Gary


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## Reggie Dunlap (Oct 7, 2010)

I realize it's not going in your walls and that you are blowing in fiberglass. My point was that cellulose is generally preferred to fiberglass in a flat ceiling application. You compared cellulose to cotton candy, said it's likely to burn, and called it crap. None of which is true. 

It's your house and you are going use the product that you feel is best in that situation. But you're not going to convince anyone who does this work for a living that fiberglass is a better blown-in product than cellulose.


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## Highbeam (Oct 7, 2010)

Reggie: I wasn't trying to convice anybody of which is better. This thread is about the doing of it, not about which material is better. Nobody ever said it was likely to burn, it's paper, make your own decision about that. And yes, it is much like cotton candy, did you listen in chemistry class? Did you even read the thread? 

I'm not buying the loss of half the R-value in cold weather. That's silly.


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## vvvv (Oct 7, 2010)

Highbeam said:
			
		

> Reggie: I wasn't trying to convice anybody of which is better. This thread is about the doing of it, not about which material is better. Nobody ever said it was likely to burn, it's paper, make your own decision about that. And yes, it is much like cotton candy, did you listen in chemistry class? Did you even read the thread?
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> I'm not buying the loss of half the R-value in cold weather. That's silly.


celluLOSE ? + SUCROSE BURN?


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## Highbeam (Oct 7, 2010)

It took me a little bit to find some quantitative analysis of this supposed reduction in R-value of blown in fiberglass and cold weather. Well, the facts are that less than a 15% reduction in R-value at 20 degrees F. This of course means your ambient outside temps would need to be much lower than 20 degrees since the attic will always be warmer than ambient outside air. Look at your climate and decide if this amounts to a hill of beans. In the pacific NW it is an insignicant reduction in R-value. 

Cellulose is very heavy too. Not so good with old 1/2" ceiling sheetrock. How do you suppose this chopped up paper handles water? Does it turn into that paper mache' junk from elementary school. 

Have you ever lit a sugar cube on fire?


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## GaryGary (Oct 8, 2010)

~*~vvv~*~ said:
			
		

> Highbeam said:
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Clearly the decision as to what kind of insulation you want to use is completely up to you and the factors you consider to be important, but the test that shows a reduction in  Rvalue of 50% was very carefully run by the National Renewable Energy Lab (NREL) using large attic simulator test rig that was built for this purpose at Oak Ridge.  
The results are here:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html

It appears to me that the test was very carefully done.  I've never seen the results disputed by the FG industry.

Figure 3 in the report shows the R value going from R19 with a 50F attic temp down to R 9.5 at with an attic temperature of -5F.  A reduction of R value by one half for cold conditions.  We get temperatures below -5F quite often through the winter.
If you don't get cold winter temps, maybe its not as much as in issue, but the R value at 25F has already dropped from R19 down to R14 -- about a 25% reduction.

Gary


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## Highbeam (Oct 8, 2010)

Bah, that link makes no such conclusions. Very qualitative. The 15% drop at 20 degrees was sourced from the same Oakridge laboratory in another "article". Seems there is no raw data available. So, we can't draw real conclusions with real numbers yet. Just because the ambient air is -5 in MT (Brrr) does not mean that your attic is -5. This is not a problem in most parts of the country so FG will only see a slight reduction in R-value, say 15% at 20 degree attic temp. Mountain out of a molehole I think.


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## Dix (Oct 9, 2010)

Well, I finally get to read this thread, and what is my conclusion, you all might ask???


It needs a different title  :coolhmm: 



 ;-P


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## GaryGary (Oct 9, 2010)

Highbeam said:
			
		

> Bah, that link makes no such conclusions. Very qualitative. The 15% drop at 20 degrees was sourced from the same Oakridge laboratory in another "article". Seems there is no raw data available. So, we can't draw real conclusions with real numbers yet. Just because the ambient air is -5 in MT (Brrr) does not mean that your attic is -5. This is not a problem in most parts of the country so FG will only see a slight reduction in R-value, say 15% at 20 degree attic temp. Mountain out of a molehole I think.




Hi,
I guess you can believe what you will, but I don't see how they could have done the test much more carefully.  They built a 14 by 16 ft section of attic with standard home attic construction, they ventilated in the same way that attics are ventilated, and they have temperature control chambers on each side.  The figure 3 data is directly from the test -- I would hardly call it qualitative.  I've been a engineer for 35 years, with a good deal of experience in setting up and running tests.  In my opinion you very rarely find tests done this realistically and this carefully.

As to -5F, most of the northern tier of states experiences these temperatures, and in the west, all the way down through Colorado.   And, the 25% drop in R value for 30F attic temps is hardly insignificant.

Gary


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## Highbeam (Oct 11, 2010)

Yeah, that graph had no numbers on the data points. Just a pretty picture. Was there an actual data table somewhere? These types of articles are often biased and especially when there is no data presented. 

Again, you're depending on numbers that are nowhere to be found. I also found an Oakridge data point of 15% drop at 20 degrees attic temp and you found something else. No clear consensus. As an engineer, you should be concerned with both actual data as well as the method by which the data was collected. Show me the data and you might have a point.


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## ISeeDeadBTUs (Oct 11, 2010)

Speaking of being blown . . .how bout using cellu*lite* for insulation?


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## Highbeam (Oct 11, 2010)

Guys like gary have actually gotten me second guessing the FG decision. Healthy I suppose. I had a roof leak over the weekend where an area of attic insulation was saturated. What happens to the cellulose stuff when it gets totally wet? The leak was a fart fan roof jack, the roofers attached it with nails that were not covered by the shingles. The exposed (gasketed) nails were enough to let in a lot of water. Enough that I had to poke a hole in my ceiling to drain it. Ugh. 

This was my first time laying in and working in the modern blown FG insulation. It was not itchy. It was like a pile of cotton balls.


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## kenny chaos (Oct 11, 2010)

Have you asked any of your local homebuilders or architects what the latest fad is?
No matter what you do, later you'll wish you did something else.
That's how that works.
You've got three pages of ideas.  Go ask elsewhere for more, differant, and maybe better, ideas.


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## sesmith (Oct 12, 2010)

My old farmhouse has has foam, fiberglass, and cellulose in it, depending on when the various parts were remodeled.  All work, but I can tell you from experience that rodents LOVE fiberglass.Not only that, if they do manage to move into the fiberglass, they trash the insulation.     They don't care for foam or cellulose nearly as much.  I hate working with fiberglass, so when it recently came to adding more fill to the crawlspace area over much of my house, cellulose won hands down.  Easy to work with relatively clean and fairly inexpensive, and not heavy.  Any insulation becomes a heavy sloppy mess when wet, but then, my roof doesn't leak (I just replaced that too).


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## GaryGary (Oct 12, 2010)

Highbeam said:
			
		

> Yeah, that graph had no numbers on the data points. Just a pretty picture. Was there an actual data table somewhere? These types of articles are often biased and especially when there is no data presented.
> 
> Again, you're depending on numbers that are nowhere to be found. I also found an Oakridge data point of 15% drop at 20 degrees attic temp and you found something else. No clear consensus. As an engineer, you should be concerned with both actual data as well as the method by which the data was collected. Show me the data and you might have a point.



Hi Highbeam,

Maybe we are looking at different articles -- this article:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html

Has a figure 3 shown here:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html#fig3

Its a plot of R value vs attic temperature.  The vertical axis is the actual measured R value of the insulation, and the horizontal axis is the attic temperature.
The plotted data points show the R values achieved for the two FG loose fill installations they did.

For example for the LSCS 1 test run: 
At 50 F attic temp, the first run shows R17.9 
At 28 F attic temp, the R value on the same sample is down to R14 
At -4 F attic temp, the R value on the same sample is down to R9.1

The data points labeled LSCS 1 and 2 shown in figure 3 are actual measured values from the two separate installations of loose fill FG they did in the test rig attic.

NREL has no reason to be biased.  They are a government operated test organization, and have an excellent reputation -- you can easily verify that with a little Googling.

Gary


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## mikeyny (Oct 13, 2010)

thanks for setting things straight Gary, I have been blowing cellulose for many yrs now. I occasionally chime in to give a bit of advice on this subject but sometimes you just can't convince some people how good it really is. Owens Corning has had the market cornered for so long, it's hard to think any other way than pink. If people had any idea how much energy it takes to produce fg compared to cellulose, they would not believe that either. Fiberglass really is a thing of the past.
                                                                                                                                  Mike


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## woodsmaster (Oct 13, 2010)

I would use cellulose if for no other reason than it dosn't make you itch.


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## velvetfoot (Oct 13, 2010)

How about a visit to a fiberglass insulation industry group website to balance things a bit:  
http://www.naima.org/pages/resources/faq/faq_fiber.html#Anchor-How-20102


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## Highbeam (Oct 13, 2010)

Modern fiberglass can be bought in itch-free versions. It's like cotton. No itch. I don't know how they do it. 

I would have to see actual data points for the graph. Show us the numbers. Engineers know that graphs are a way to trick accountants.


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