I roasted a couple of pounds of a new Guat yesterday (one obtained locally). I got a little farther towards the dark side than I normally roast. It went quite a few snaps into 2nd, but never hit "rolling 2nd crack" nor is there any real oil showing after overnight rest. I brewed a pot of this after just 3 hours rest and then another this AM after 12 hours rest. All of a sudden, the SMP grinder is getting "static cling" in a serious way! The weather here in Houston was not particularly dry yesterday. (In fact, you're had pressed to find a day in Houston where the humidity is much less than 65%.) Since this is one of the few times I have roasted to FC or FC+ and also one of the few times the grinder has had a static problem, it got me to wondering if the darker roasts have more static issues than ligher roasts. I haven't changed anything with the grinder. I didn't just clean it or remove the burrs. Has anyone else noticed this before? Safe Journeys and Sweet Music Justin Marquez (CYPRESS, TX)
I find just the opposite. When I roast for brewed, fines are everywhere when I grind, the lighter the color, the lighter they seem to weigh. Dark roasts (espresso) seem to hold the oil better when they grind, they slide right out of the hopper. :)
I use a wooden level when I level grinds in my espresso baskets. Dark roasts always stick to the wood and are difficult to level without disturbing, and there's no noticeable improvement when I level with my fingers. None of this happens with lighter roasts. I assume it's that the beans are oilier. --Derek On 3/19/07, Justin Marquez wrote: <Snip>
I don't think a slight change in the moisture level of the bean due to a darker roast could affect the electrostatics to a noticeable degree. Certainly it takes less energy to move a grind which has less weight but a significant change in "static cling" would probably be more attributable to less relative humidity in the environment.
The temperatures involved in coffee roasting tend to drive out moisture by converting it to very high temperature water vapor. I doubt if the presence of humidity precludes the generation of static charges. Clouds in the sky are the epitome of humidity, but they can sure generate static! My roasts sometimes form oil drops after a few days' rest. The customer servicing Automaton for a well-known importer whose machines appear in the market wearing several different Marques told me the oil drops must be the cause of all my grinder problems. When stored in an open pile, the coffee hydrocarbons tend to adsorb and bond with O2 molecules. The evolving CO2 molecules from the aging coffee beans tend to do the same with passing H2O molecules. If The Inspectors find coffee grounds hiding in your grinder, it means you just haven't cleaned it yet. Cheers -RayO, aka Opa! I am prejudiced when it comes to inviting water molecules over for coffee beans.
On 3/19/07, Tom Ulmer wrote: <Snip> I agree that the moisture level in a recently roasted batch is LOW, regardless of whether the roast is City to FC+. You've heated the beans to 400+ degrees - the water is gone. As a matter of routine, I "huff" once into the plastic catchbin just before I grind to brew, just to help quell static. I did that with these two grinds and still had LOTS of static. Typical with the SMP is to have a few grounds to cling - I grind about 55-60 grams in a batch and the amount normally clinging in the bin would cover a patch about the size of a thumbnail, 1 layer thick. After pouring the grinds into the drip filter, I take the bin to the sink and rap it against my hand with the bin's opening looking downwards and the remaining grinds fall out to the disposal. This morning when I pulled the catchbin out of the SMP, a few grounds and chaff exited onto the counter. After pouring the mail grinds to the filter, most of the inside of the bin was covered with grounds and a little chaff (I did have more residual chaff than usual in this batch after fan cooling). When I turned over and tapped it as usual, not much of the clingers fell out. I had to rinse it to clean it. This is the level of difference in static I am seeing. Safe Journeys and Sweet Music Justin Marquez (CYPRESS, TX)