Biab, Why Nylon?

[pdilley]

I've got both swiss voiles, the polyester and the nylon one. The BIAB guide calls out for nylon but did not have a reason why?

I've been digging through Nylon 6, Nylon 6,6 and Polyester FAQs and Polyester seems to have a much higher melting point over 300 C, some over 400 C. Nylon has a lower melting point.

Polyesters are many but most unspecified refer to PET (polyethylene terephthalate) which is what the Brew Bottles are made of.

Of course I don't think we'll see a data sheet on the polyester in the Chinese Polyester Swiss Voile or the Turkish Nylon Swiss Voile, so its a bit of speculation on the part of which formulation is used by the manufacturers.

That said was nylon chosen because that was what was available on the shelf when BIAB was written at the local Spotlight? Or is there a reasoning for the choice?


Cheers,
Brewer Pete

 

[flattop]

Adds an interesting dimension to the No Chill debate if PET is good to 300*c

No idea why Nylon over Polyester but even Nylon doesn't have a problem at 100*c as long as it doesn't burn on the bottom.
One point, perhaps it is stronger for the weight???

 

[smollocks]

To my knowledge 100% polyester is recommended on this forum. See the Spotlight product tag here.

 

[seravitae]

It might be possible with PET to undergo transesterification of the terephthalate with ethanol from your batches, leading to polymer degredation and possibly contamination of your batch, although im pretty sure the mono- and di-ethyl terephthalates are solids, with low solubility.

I am sure some studies have been done on it, but it does make you wonder. Esters are formed by acidic catalysis of acids and alcohols, and the product exists in an equilibrium in solution. Since our washes are acidic, it is possible that catalysis can occur, leading to hydrolysis/transesterification.

 

[pdilley]

To my knowledge 100% polyester is recommended on this forum. See the Spotlight product tag here.

I remembered that tag photo when I went in.

I did got the BIAB information web site and downloaded the PDF and it said get Nylon Swiss Voile so that through me for a loop. I asked the ladies in the shop for Nylon and they could only find Polyester so I bought it. Then the day before leaving Wollongong I walked through the shop for something to do for an hour before checking out of the hotel and saw an almost used up Swiss Voile roll. I read the tag and low there was Nylon Swiss Voile from Turkey. Cost a dollar more a meter but getting 150cm by 150cm of it for enough to play with, we are only talking a $1.50 difference. So now I got both.

Just have to decide which one to sew up for BIAB, for filters during pour into no chill jerry's, and which to sew up into socks for hops or other purposes if there is one.

The new Robinox is supposed to arrive Thursday so was going to hold off until then or maybe just take it in to a alteration shop to sew into a large pillow case, just have to decide if regular thread will hold out or should switch to something else such as fine diameter fishing filament to sew it up with.

 

[flattop]

Pete, you really want a double stitch, 5k of dry grain becomes Xk of wet grain so the seams have to be strong... Nylon thread not cotton...
Also the shape of a pillow case is wrong, you want a round bottom to the bag so the grain doesn't get caught in the corners...

 

[Bribie G]

Pete, Flattop is dead right, if you go the pillowcase design, on hoisting, you end up with a rather naughty looking bag that looks like an enormous version of one's jewels, and you can bet that the wort stream from each lobe will miss the edge of the pot.

What you really need is a design that looks like a giant can of baked beans and when hoisted it will take on the shade of a teardrop.

I have the dogs bollocks variety and I have worked around it , but for my next bag I'll get the sewing lady to make up the can o beans design for me again.

 

[pdilley]

I get ya guys,

Like those round collapsable cloth storage devices at the $2 shops. For putting shoes or god knows what in.

Or those old school gym bags that were round duffel bags

 

[flattop]

My bag looks like an abortion, my mate and i sewed it up one saturday, neither had used a machine before, it's crooked and lopsided and the seams are all over the shop....
But it works well, it's a cylindrical shape which is priority one and it's diameter is just smaller than the urn which is priority 2.

Basically you want to avoid folds or places where the grain can hide... think about your grain going commando... you want it running free, spilling it's wild sugars all over the urn
It's the tighty whitey VS boxer debate.... Do you want your grains strangulated by the wrong fitting?

Forget about the visual picture of Bribie's knackers (and the fact he cant aim straight and misses the side of the pot)....

get the pattern right and it will help your efficiency

 

[flattop]

Yeah thats the one, the collapsable storage devices.... exactly

 

[pdilley]

Heh I'm sure Michael takes no offense.... even though the thought of that is a might more powerful than Maggie Thatcher naked

I've just got to wait patiently for the Robinox to arrive and get to measuring. Earliest will be this Thrs night.

 

[flattop]

BP thats offensive... the iron maiden with her kit off... i'm gonna have nightmares tonite...

 

[pdilley]

You're welcome... its the English be all, do all, wonder cure for any embarrassing situation an English chap could ever find himself in

 

[flattop]

Like a pollie in womens underwear.....

 

[Ross]

Polyester was always the material quoted originally, not sure why the guide has stated nylon.
Polyester would be my material of choice.

cheers Ross

 

[pdilley]

Thats good to hear Ross.

I swear it also made it all the way to the States as nylon was mentioned either on the brewing radio or thet video podcast on the Australian BIAB method.

 

[Mantis]

Round bottom pussys
Pillow boy here and just grab one of the corners as you pull with the other hand, then you get a lovely pointy bottomed bag.
Burns your hand but meh, do you want beer or what
<_< :lol:

Hey, check the pic in my sig

 

[crundle]

There was a thread about this sometime earlier, where it was stated that the call for nylon in the pdf is incorrect, and that it should be polyester.

As for the bag design, I had the lovely missus sew up mine in the can design, but made mine 20mm greater in diameter than the Crown urn I am using, so that the excess length could be folded over the top of the urn to take up any slack. I guess this will leave the possibility of some folds being present, but I have not had any issues with my beers that I am aware of.

+1 for double stitching, as a full bag (ahem...) weighs a fair bit and puts a lot of stress on the seams, especially in a large grain bill of over 7kgs. I would also go for stretch stitching to further strengthen your seams. Mine worked OK for a few batches, but after a 7kg bill it started to show signs of tearing starting around the seams after I was squeezing the bag to extract more wort as I normally do.

For my next big grain bill, I am planning on getting a large piece of Swiss Voile and placing it in the urn like a giant pudding bag, so that I can raise it and squeeze the wort out without worrying about seams tearing.

Here are some pics of the bag being made. I left 20mm each side extra to allow for the double stitching.







cheers,

Crundle

 

[pdilley]

Yes, good info, tha PDF really needs to be destroyed and a corrected versin placed online. I went bacl to some of thr radio shows and both nylon and polyester are mentioned so the nylon mistake has already spread to the states and disseminated to home brewers there.

I also had thought about the pudding bag as no seams would be stronger. 1.5m by 1.5m square is huge and should easily be up to the task. Then a simple twist on the loose ends and lift or a twist, tie with rope and hoist and you'd be set.

 

[Gregory]

I use a two-metre circle of voile. Not a bag, just a circle of fabric hemmed at the edge. Put the grain in, gather up the edges and tie around the top in a clove hitch with 8 mm rope. What this gives you is a large tea bag. Dunk; leave; dunk again from time to time during the mash. Works like a charm.