Good news on this!
Had yesterday off and was able to do a mini experiment. I had 1.3kg of crushed grain lying around in my fridge too old to be used for a proper brew. Using Ross's hopsock I mashed and boiled it. Here's the results.
Procedure
1. Mashed 1.3kg of grain in 7.8 litres of water pre-heated to 71 degrees. Struck at 64 so immediately raised to 66 through force of habit.
2. Mixed up grain in hop sock vigorously quite often during first 20 minutes and then every 15 minutes thereafter. Did this as grain was tight in the bag. Refractometer readings were 1041 at 55 minutes. 1044 at 80 min. 1047 at 100 min. As a matter of interest and because the grain was so tight I kept the mash going.... 1049 at 120 min and 1049 at 150 min. (Unfortunately, some of the earlier readings will be inaccurate as I probably didn't cool the wort for long enough in the refractometer.)
3. Mashed out 5.25 litres at 1049 which gives efficiency into boiler of 70%. I'm not too sure how this figure translates to, "Efficiency into Fermenter." Hopefully there's not much change???
4. Boiled for an hour just to see how much scum formed and how much trub was left.
Comments
Clarity: No worries at all. Hardly any scum. As for trub, I'm guessing that it was actually far less than from a normal mash. The hop sock is 250 micron mesh (0.25mm) so when you think about it, not much is going to get through.
Efficiency: No worries, I think (see 3 above)???
Weird how the grain retained 2.5lts of water and this was after squeezing the bag. Am hoping the grain was measured accurately at the shop. Couldn't be too far off though.
Problems/Solutions
The grain was quite tight in the hop sock hence the reason why I actively stirred it up so often and extended the mash time out to 2.5 hours. Also temp in the middle of grain was always about 2-3 degrees lower than the surrounding water. Ross's jumbo hopsock will not make a difference either as the diameter of the jumbo is the same as the small hopsock. To solve these problems and to get back more to Jame's orioginal idea, I'm hoping Ross can source me a wider diameter bag. By fixing the above, the mash time problem should be solved as well.
Poppa: I think a grain bag will release too much husk into the brew and therefore tannins in the boil. Like your colander idea but watch what sort of plastic it is, i.e. toxicity. Ross's hopsock has a nylon ring to hold it open. You can see a pic
here
Clarit
James: I know the hopsock is a little off your original idea but certainly the same principles apply. My thinking is that the hopsock material is going to save a lot of problems, work, money and cleaning. And you need no pump which is a huge expense. Cool! The container with holes and/or mesh also worries me a little as I'm guessing that it would be time-consuming but, really, I have no experience to base that comment on.
Finally
It looks as though it will be up to us newer AG'ers to experiment with this one. After talking with some more experienced brewers, they can't see anything wrong with the principles. Because they are already set up though, there is no real advantage for them to experiment with this method. The main criticism was the amount of unknowns in the idea. The above experiment seems to have got rid of some of the main ones.
The reason I'm so into this idea is two-fold. If this works, I can actually throw kettle, sock, burner and bottle into my van and brew while I work. How cool is that?
Secondly, if brewing in my small apartment, this is going to save a lot of space, set-up time and active time etc., required for a brew.
I also think that this would be a brilliant way for those wanting to give AG a bash as it's very simple and very inexpensive. Not saying it would work for all beers but at this stage can't see why not.
Hopefullly Ross can source me a wide diameter sock and I'll be able to do a full scale test run soon. If the first experiment works OK, I'll follow it up with a double brew day. One brew with this method and another identical brew using traditional equipment.
Once again excuse the long post. Seems to be that I write the same length posts whether sober or not - lol!
Thanks again James for raising the topic.
Cheers
Pat