Bob,

Thanks! Great video.

The original posting here and on HomeBrewTalk dealt with the BB&B bag. Mine was an update on a source for a similar bag.

There are a lot of folks advocating the use of a 5-gallon paint strainer bag, which is even coarser than this one. I am actually starting to wonder what the quality difference in the finished beer is with a paint strainer bag vs. a real BIAB bag. It might be an interesting side-by-side test. Question to ponder: Is BIAB getting a bad name from people using these coarse bags and making crappy beer because of them?

The BB&B/Marshall's bag is a step up from a paint strainer bag, but still cheap. I agree that the mesh is not as fine a voile. It is a starting point for someone who wants to try BIAB, though.

I recently had a friend make a voile bag for me, sized for my pot. That is what I'll be using from now on.

I don't know how much variation there is in voile. I'll have to go home and do a thread count (based on PP's post, above, I need 30-40 threads per cm).

Good Day, I do not want to cause a problem....I have used the 5Gallon Paint strianer, normal "curtin" voile, Very Fine "no-see-un" voile, AND Polyester Linen(think table cloth).

Depending on your Grind, a superfine grind(flour), needs the finest weave you can find.

A standard 0.2MM grind does needs a Fine voile Cloth.

A normal LHBS grind works very well with the Normal Voile.

But, if you don't mind a handful of finely ground Husks and the resulting "mud" in your Kettle, the 5 gallon strainer bag works quite well with the standard LHBS type grind!!!

You may find, depending on your recipe, a small bit of Tannins in your beer.

smyrnaquince,

As you can see from my video. I made a double lined bag. I have plenty of friends who made their own bag with one layer of voil and it works great. The two layers were a consequence of my 35 years working for the phone company were we left nothing to chance. We over engineered everything because good service was everything to us.

Where am I going with all this? I don't know? I forgot what I was leading up too? (I have been testing different beers all day) Anyway, my hand was visible thru two layers of voil (drapery material)so you can see it is very fine material but even with two layers the bag drains instantly for me. So with this material nothing but wort goes thru. There is no grain or husks to desolve tannins (bitterness - astringency?) into my wort.

I have the paint thinner bag and the laundry bag that people have been trying in my brewing kit. I use these as props in my BIAB demonstrations and classes that I present at various events. I don't recommend using them because the proper voil material is cheep and easy to make into a bag. Why use a substandard ill fitting item when making the form fitted proper bag is so cheap or cheaper than a off the shelf make do one?

I burned a hole in my brew bag (while filming a video, so stay tuned for that) A handful of grain and husks (or more?) went into my wort and led to some astringent beer. At least I perceived that? So in short (to late for that) I recommend that new BIAB'ers just make the proper bag and be done with it! BIAB is (totally awesome) so the bag will be used again and again!

Sorry for the rambling. As I said I have been testing beer all morning and I am a bit confused about everything at the moment. I have made one decision and that is the beer on tap 3 was the best! Or was that tap 4??? Oh well back to the testing!

Bob, I was Cheap and cut a square of Matrial to fully fit the Kettle, and rounded the corners, and a Bungee cord to hold it down.

It works very well as a "Hobo Bag".

Very cheap and NO labor!

Joshua,

I works well so use it! You are a prime example of the simplicity of BIAB! We all know you are a good brewer and you brew without "fancy stuff". Whatever works go for it!

[Edited--Corrected units for the thread counts for Marshalls bag. I had called out cm instead of mm!]
[Edited again for an update on the "thick" bar's effect on pore size.

OK, I just darn-near went blind measuring my new voile bag. 30 threads per cm, which meets PP's 30-40 threads/cm from Post #4. I hope that this suffices. I intend (hope?) to do a double crush at the LHBS with their standard roller settings.

(Do you guys use something finer?)

I also measured the Laura Ashley bag from Marshalls (second picture I posted, "Bag Weave Detail.jpg"). For the curious, the spacing between the thick "bars" is 1 mm. In the other direction, there are 6 threads/mm. However, the thick bars are rather thick, so the opening between them is more like 2/3 mm.

As I said, I now have a voile bag and so I don't need to use the Marshalls bag.

BobBrews wrote:Sorry for the rambling. As I said I have been testing beer all morning and I am a bit confused about everything at the moment. I have made one decision and that is the beer on tap 3 was the best! Or was that tap 4??? Oh well back to the testing!

smyrnaquince wrote:OK, I just darn-near went blind measuring my new voile bag. 30 threads per cm, which meets PP's 30-40 threads/cm from Post #4. I hope that this suffices.

Lol Dave . I think 30 is great. I think my first bag was 30 and the ones I use now are 40. There was no waiting around for draining with the 30 but there is a little with the 40. Be interesting to see the difference the two 'weights' working as BIAB bags and hop socks. I think the 30 might be just as good as the 40. Regardless, you are definitely in the right territory now Dave. Let us know what difference you notice between your new bag and the paint strainers.



P.S. If your eyes can handle it or maybe you have counted them already, I'd love to know how many threads per cm in those paint strainer bags.

[I just edited my earlier post. I typed "cm" instead of "mm" on the Marshall's bag measurements.]

[I just edited this one, as well. Updated measurements for the Marshalls bag and new ones for the paint strainer bag, as well as updated my math:

• Marshalls bag: the spacing between the thick "bars" is 1 mm. In the other direction, there are 6 threads/mm. However, the thick bars are rather thick, so the opening between them is more like 2/3 mm.
• Paint strainer bag: Measurements are the same as for the Marshalls bag, but the threads are thinner and that thick bar on the Marshalls bag is a thin one here.

]

So, the voile acts as a strainer, as does the grain bed in a 3V setup. I wonder what the effective "pore size" is in a grain bed?

Years back when I was looking into water filters for backpacking, I kept running into "nominal" vs. "absolute" filter pore size. With the varying shape of the holes (pores) in the Marshalls bag, this is a similar situation. Assuming the thread thickness is zero and averaging the size of the Marshalls bag pores, I get these pore sizes:

• Super BIAB Bag: 40 threads/cm = 4 threads/mm => pore size = 0.25mm x 0.25mm = 0.0625mm^2
• BIAB Bag: 30 threads/cm = 3 threads/mm => pore size = 0.3333mm x 0.3333mm = 0.1111mm^2
• Marshalls Bag: 1 "thick" thread/mm x 6 threads/mm => pore size = 0.6667mm x 0.1667mm = 0.1111mm^2 (average)
• Paint Strainer Bag: 1 thread/mm x 6 threads/mm => pore size = 1.00mm x 0.1667mm = 0.1667mm^2 (average)

So, the average pore size is the same for the BIAB Bag and for the Marshalls bag, but the latter's pores are rectangular/triangular, with the long dimension about twice that of the BIAB dimension.

Does all this mean anything? No. Do I have any idea of the particle sizes of crushed grain? No. I just like playing with the math.

Hmm.
If the effective pore size of the filter (BIAB bag or grain bed) is similar, then the the other difference (that I don't think I've seen mentioned) is the lack of a vorlauf in BIAB.