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Ike Mouser
(isaac.mouser) - F
Cheapest 900FP down on 10/25/2010 20:24:15 MDT Print View

Where is the cheapest place to buy 900fp down for making gear?

Dustin Short
(upalachango) - MLife
Re: Cheapest 900FP down on 10/26/2010 01:32:51 MDT Print View

Thru-Hiker.com has 900FP down for around $10/oz (sold in 3 oz increments...ie $30 for a 3 oz bag). I've looked elsewhere and Thru-hiker is really the only place that I found that easily sells 900fp down to the DIY crowd.

If anyone knows another source, I'd also be greatly interested.

Ike Mouser
(isaac.mouser) - F
cheaper on 10/26/2010 07:42:18 MDT Print View

hammockgear.com is cheaper. im confused though, they say its the same fp they use in their quilts, but their quilts are 900 this is advertised as 800. are they the same or not?

Dustin Short
(upalachango) - MLife
Re: cheaper on 10/26/2010 08:38:10 MDT Print View

Hammock Gear's quilts are standard 800fp with an option to upgrade to 900. From what I can tell, they sell just 800fp to the public...which is why it's probably cheaper than thru-hiker.

EDIT: if you look at hammockgear's quilts, the upgrade to 900fp usually costs roughly $3/oz of fill. If you extend that cost to their DIY down and assume it's 800fp they're selling, you get approximately $9.50-$10.00 per oz as the cost for 900fp. This is comparable to the price at thru-hiker which inclines me to assume they are selling 800fp at the $6.50/oz price (in addition to their site repeatedly stating it's 800fp for DIY).

Edited by upalachango on 10/26/2010 08:43:48 MDT.

Tim Marshall
(MarshLaw303) - MLife

Locale: Minnesota
Re: Re: cheaper on 10/26/2010 08:49:31 MDT Print View

tree to tree trail gear sells 900fp but i think the cost is similar the T.H.

-Tim

Rog Tallbloke
(tallbloke) - F

Locale: DON'T LOOK DOWN!!
Re: Re: Re: cheaper on 10/26/2010 08:55:55 MDT Print View

How much warmer is 900 compared to 600? 1/3rd?
600 fp down can be had for $3/oz

Eric Lundquist
(cobberman) - F - M

Locale: Dry side of the Eastern Sierra's
Re: Cheapest 900FP down on 10/26/2010 09:08:44 MDT Print View

"How much warmer is 900 compared to 600? 1/3rd?
600 fp down can be had for $3/oz"

Down is measured in fill power.
900fp: 1oz = 900 in^3
600fp: 1oz = 600 in^3

This is the amount of space one ounce of down occupies. For example, in a 4'x8' quilt (4608 in^2), 9oz of down would give you different loft measurement.

900fp: 1.76"
600fp: 1.17"

Likewise to get 2" of loft, you'll require less down with a higher fill power rating.

900fp: 10.24oz
600fp: 15.36oz

Rog Tallbloke
(tallbloke) - F

Locale: DON'T LOOK DOWN!!
Re: Re: Cheapest 900FP down on 10/26/2010 09:14:19 MDT Print View

Thanks Eric, I understand the difference in volume. I'm wondering if anyone has any opinion on how much extra warmth the increased loft gives. In my experience, high fp rated clothing sags in the damp sooner than lower fp rated clothing, which has more 'structure' in the down.

My thinking is that in bone dry conditions, high fillpower is the clear winner, but when the going gets damp, then lower fp might prove the more resilient after a day or two.

Dustin Short
(upalachango) - MLife
Relative Warmth on 10/26/2010 09:37:15 MDT Print View

Depends on how you're comparing. Based off the VERY limited data for clo of down fill powers I assumed a linear regression and get about 2.1clo/oz-m^2 for 900fp and only .9 clo/oz-m^2 for 600. That's ~2.33X (233%) the insulating power of 600fp. 900fp has less feather shaft than lower quality fp which may account for clo values increasing at a greater rate than weight savings.

If we assume that 900 and 600fp have same clo, just different weight, then 1 oz of 900fp is 150% as insulating as 1 oz of 600fp, ie 50% warmer for the weight (900/600=1.5). If you want the "same" insulation value, you need ~66% as much 900fp down as 600fp.

For real world applications I would split the difference and come up with 900fp down being approximately twice (2x=200%) the quality of 600fp. Meaning you can use half the weight of 900fp to achieve the same warmth as 600fp

So lets do a cost analysis:

Lets say we're making a down hood (keeping numbers simple just as illustration) and we want 1 inch of loft and our pattern calls for 600 square inches of head coverage (I know this may not be accurate, bear with me it's just to illustrate a point). This gives us a nice 600 cubic inches to fill the hood. I'm going to assume the conservative numbers based solely off weight savings and say that 900fp and 600fp have same insulating value just different densities.

We need 600 cubic inches of down:

600fp=>600c.i./600fp*$3/oz= $3.00 @ 1.0 oz and 1" loft
900fp=>600c.i./900fp*$10/oz= $6.67 @ .67 oz and 1" loft
900fp=>900c.i./900fp*$10/oz= $10.00 @ 1.0 oz and 1.5" loft

So based off performance alone 900fp is at most 2.25 the cost of 900fp. This goes down if you assume that clo/inch increases as down quality increases. You do pay for quality, but that quality comes with the benefit of more warmth and less weight.

EDIT: Rog, you're probably correct about damp conditions and lower quality down maintaining it's loft better due to the extra quill inherent.

Edited by upalachango on 10/26/2010 09:40:05 MDT.

Dustin Short
(upalachango) - MLife
Re: Relative Warmth on 10/26/2010 09:46:13 MDT Print View

So a bit more info for you Rog. In bone dry conditions, based off my linear regression (without more data available I can't try a more complex/accurate regression unfortunately. Just two data points):

Clo per Inch chart of various Down.

The bolded items are the two data points I had to make my linear regression (Down fp and clo/oz-m^2). How this helps for wet conditions and collapsed loft is up to you to decipher. Just don't get wet imo ;)

Ike Mouser
(isaac.mouser) - F
wow on 10/26/2010 10:50:06 MDT Print View

Thanks for all that work Dustin!

Dustin Short
(upalachango) - MLife
Re: wow on 10/26/2010 11:09:19 MDT Print View

Actually most of the credit goes to Richard Nisley, another BPL member. He's done an extraordinary amount of research on insulation values of both down and synthetics, and is more than willing to share with the BPL community. Very knowledgeable individual.

My work is "standing on the backs of giants." He has provided a lot of the primary data that I just try to communicate as clearly as possible for both the novice and the experienced alike.

EDIT: Still wish I could find another source for 900fp down as well, just for the sake of competition (I've nothing against thru-hiker). But so far still haven't found one, probably need to make the leap and start making those dreaded phone calls. So far the economics look like roughly $10/oz though regardless.

Edited by upalachango on 10/26/2010 11:12:11 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
dollars per ounce saved on 10/26/2010 11:14:55 MDT Print View

I always like to figure out how many dollars it takes to save a particular weight in the finished product.

For example:

I want to make a vest that's 48 inches wide x 28 inches long = 1344 inch^2.

I want it 2 inches loft = 2688 inch^3.

I want to overfill it by 20%, so:
600 fill = 5.4 ounce = $16 @ $3/ounce
900 fill = 3.6 ounce = $36 @ $10/ounce

So, to save 1.8 ounces in the finished product, it costs $20 = $11/ounce.

Just as a comparison, I recently spent $100 for an air matress that was 16 ounces lighter than what I had, so that was $6/ounce saved.

Or, I'm thinking about remaking a tent that uses 13 yards^2 with 0.75 ounce per yard^2 fabric rather than 1.4 ounce per yard^2 silnylon - $100 for the fabric - it will save 8.5 ounces = $11.8/ounce saved.

Dustin Short
(upalachango) - MLife
Re: dollars per ounce saved on 10/26/2010 11:35:15 MDT Print View

Very nice Jerry. Of course I'm still building my kit (I live in the desert, what's this insulation your backpackers speak of?). SO sadly nearly all my purchases are increasing my weight and decreasing my bank account. But it's better than freezing on a mountain naked. The nice thing though is if I pay the higher cost up front, I don't have to upgrade later, it just takes longer to fully equip.

Rog Tallbloke
(tallbloke) - F

Locale: DON'T LOOK DOWN!!
Re: Re: dollars per ounce saved on 10/26/2010 13:05:22 MDT Print View

Thanks guys,
very helpful figures. The seller on the 'bay with the 600fp down just emailed to say she was unimpressed with the amount of quill and has offered a refund.

Ho hum, back to the drawing board. I'm making a cuben quilt, so I guess I'll bite the bullet and spend more on the down, to get a result which justifies the expense of the shell.

A good secondhand sleeping bag may be the way to go for me.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Cuben quilt? on 10/26/2010 13:15:39 MDT Print View

I don't think you want to use Cuben for a quilt.

It's waterproof.

Sweat will condense on the inside and get the down wet.

Dustin Short
(upalachango) - MLife
Re: Cuben quilt? on 10/26/2010 13:43:45 MDT Print View

I agree with Jerry. Unless you want the vapor barrier effect for winter camping...in which case you'd probably want 900fp down anyway (more warmth and MUCH less weight when you start using a lot of down).

todd harper
(funnymoney) - MLife

Locale: Sunshine State
Re: Cuben quilt? on 10/26/2010 13:57:02 MDT Print View

There are quite a few happy Cuben quilt owners.

Eric Lundquist
(cobberman) - F - M

Locale: Dry side of the Eastern Sierra's
Re: Cuben quilt? on 10/26/2010 13:57:10 MDT Print View

Cuben fiber has been used successfully by many for their quilts. It does involve a vapor barrier which may scare off some people but it is effective.

enlightenedequipment is one cottage maker that I'm familiar with that uses it.

Edited by cobberman on 10/26/2010 13:57:42 MDT.

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Down for Cuben Quilt on 10/26/2010 14:06:03 MDT Print View

Jerry and Dustin, there is a large amount of information on these forums about down-insulated cuben quilts, and quite a few people who post to this site own them. Tim Marshall has been making them for quite a while. An early model he made (with the "skunk stripe") for Steve Evans caused quite a stir and provoked a lot of discussion. Your concerns, and many others, enjoyed a good deal of debate.

First, cuben is typically used for both the inner and outer shell (I assume that this is Rog's plan), so the only water vapor that enters the down from evaporated perspiration is what little can pass through the needle holes at the seams. Reports from owners of the quilts seem to indicate that wetting of the down is only a problem when mist or rain wets the outside of the quilt and water drains into the down through the stitching. The down gets wet from the outside just as easily as it would in a quilt with a fabric shell, but a cuben quilt takes somewhat longer to dry.