The Soak

[SusanJoM]

Hank and Edbtjon and the rest of you proponents of 'starting low'??   

Here's Scott Rao's take on the subject.
http://scottrao.com/blog/the-soak/

[easygene]

This information from Scott Rao is so timely and lends validation to this method.  The Soak.  Ha ha

Still roasting with heat and fan off for first minute to minute and a half.  Grate stays closed always as to remove all variables for next few months.  Some roasts for espresso and some for pour over.  All beans high density.  Always with Huky heating for 20-35 minutes.
Believe the dark patina of my drum insures it gets and stays hotter but realize its thermal mass may limit lt.  Compared to my old Gene Cafe it's a tank!

Really happy with results so far

[edtbjon]

Yup, read it (check ). I've been doing this for almost a year now. The Huky is a bit of a special machine with its relatively very low mass, but my approach going for a TP around 80C/175F (or less) really needs the heater turned off for 70 seconds, so that I get my TP at around 1.25-1-30.

[SusanJoM]

Yup.   Sounds right to me  -- for a solid drum.
I'm still not convinced that it works with a perforated drum.
There's something about the constant closer balance of heat and air on the outside and the inside of the drum that makes the whole roasting process totally different.

IMNSHO 

[edtbjon]

Personally I feel more confident using the solid drum, with which I've found a decent basic profile. I do have a perforated drum in my closet, so running a series of tests is possible, but I do have a life to live too. I'm still not convinced of the perf setup really needing a totally different approach compared to my usual basic profile. The difference in drum mass is really obvious.
(My experiences with the perforated drum was so-so. I got decent results, but mostly kind of replicated and adapted my solid profiles to the somewhat different machine, a profile which doesn't really represent my current style of roasting. A new set of trials would probably be a lot of fun, but it would take a few weeks to learn how to get the best out of the perf. setup, after which I have to rebuild the machine and get the best out of my solid setup for a valid comparison... A lot of rain in the early summer season will do it, staying inside just roasting coffee... )

[Brent]

I read it too.  While I do believe the soak can be useful, I too am  not convinced of it's use with a perforated drum, but perhaps it can be done to a point on a perf. drum.

 I assume that the point of the soak would to  be to not shock the beans. Rather,  to give them some time to acclimate to the hot drum while still "soaking" up conductive heat from the drum and not getting blasted with high heat immediately. A larger machine would certainly have more thermal mass than a solid drum Huky, but it seems to work with the Huky too, as people do it.

I suppose this could work to a point with the perforated drum, but the technique would have to be slightly different. After charging, perhaps add around 2Kpa of heat for the first 30 to 45 secs, rather than high heat immediately. I have tried this, but with a charge weight of 300 grams (charge temp of between 400f - 420f depending on bean)  and still got a turnaround at about 1:40.
Unfortunately, I can't yet speak to how it affects the cup because I haven't done a direct comparison. Has anyone cupped a soaked and non soaked roast of the same bean and profile?

[SusanJoM]

I assume that the point of the soak would to  be to not shock the beans. Rather,  to give them some time to acclimate to the hot drum while still "soaking" up conductive heat from the drum and not

Can anyone propose a way to test the temperature of the drum itself?  It would be interesting to know how closely our theories about the leakage of heat through the perforated drum and/or the heat holding of the solid drum actually adhere to reality.

I love a good experiment 

[Brent]

Joe, from the Mill City vids, does mention that if too much heat is applied to the bean too soon, it can cause a vapor barrier of sorts inside the bean.  Then the bean will not soak up heat as well. Perhaps another reason for the "soak"?
He mentions using a higher drop temp, but less initial heat with a dense washed bean and a lower drop temp, but hit the heat harder, with a Brazilian style bean. (I wonder if he would apply to Island beans too, since they are generally softer and less dense? Hawaiians, Jamaicans) I wonder if his reasoning that the softer bean won't build up that vapor barrier as much because it's not as hard and dense?
 
I have to say, I was surprised to hear this,  as it goes against the method I have always used with the Behmor (of course it is a different animal compared to the Huky) and what I thought would apply in general to softer beans; IE: Lower heat in general throughout the roast

I hope I can find a video of him roasting a soft bean as I'm assuming he must back off the heat substantially at some point

[hankua]

One of the aspects of the "soak" is to charge the empty drum with a lot of heat and then lets the beans "soak" it up. I observed this recently with the Mercury electric Roaster, Scott won the Taiwan roasting competition last year, it's really competitive. He managed a very short Nortic roast using this method.

The Huky doesn't have the mass of the Mill City machines; they have 5mm thick drums, even the little one. And they have insulation another big difference.

So yeah you can charge a little higher then turn off the gas and get to the same turning point.

[Mayowarlord]

Is anyone using the soak with 500g charges ? I'm just worried that low/no gas could be problematic with such a high charge. I am thinking I might leave the air off though. I am typically running around 20% fan at the lowest.

[hankua]

If you go back and see the designer video, he roasts with the vent tube off for the first leg of the profile. With everything attached you still need some air flow.

So basically I'd run the machine at a 2nd crack temp for five to ten minutes, then let it cool down to the charge point for a "soak"

Then I'd try two scenarios, one where the gas low/air low and the other gas off/air low for a "soak"

If the turning point is dropping off, turn the gas on earlier. Do you use maxium gas 4kPa after the TP with 500g charge?

[edtbjon]

Is anyone using the soak with 500g charges ? I'm just worried that low/no gas could be problematic with such a high charge. I am thinking I might leave the air off though. I am typically running around 20% fan at the lowest.

I always use "the soak" when roasting. While I usually roast 400g charges, I've done 500g too. There are a few tricks to it. First, I use a regulator which enables me to crank the heater up to 5 kPa (but 4 kPa will do...). Second, the heater is much more effective with just a whiff of air going through the system.
I typically aim for a TP of about 75C/167F or even lower. I get there with a charge temp of about 170C/335F, no heat for 70 sec. With this approach I aim for my DE at 6.00 min.
About the airflow, I think it's important to restrict the airflow to a minimum during the drying phase, letting the water and steam build up inner bean pressure for the upcoming Maillard process (putting it very simplified...). But without any airflow, the heater is very uneffective, so with my Variac clone I found that a setting around 30-35% just made my cig.lighter flame get a bit bent into the tryer hole. (There's a short MillCityRoasters video on how to set airflow with the help of a flame...)

[Mayowarlord]

Do you use maxium gas 4kPa after the TP with 500g charge?

Yup, I am maxing out at 4 Kpa, though I am considering getting a regulator that will allow 5.

[hankua]

Do you use maxium gas 4kPa after the TP with 500g charge?

Yup, I am maxing out at 4 Kpa, though I am considering getting a regulator that will allow 5.

I don't think using the extra 1kPa is going to make a huge difference, it is on the expensive side. Another trick to try might be using some sort of insulation over the shell, like a welding blanket or ceramic with a cover.

There is a 80% rule, where most roasters work better at less than full capacity. There are exceptions to every rule however and giving the Huky a little help doesn't hurt like: roasting indoors, away from drafts, cold garages, insulation, etc.

[SusanJoM]

Here's the latest iteration of my insulating efforts