Sap brix vs. niter build up

[doocat]

A question probably for Dr. Tim. We boil at 15-16% concentration . As the season progresses niter builds/darkens faster on the front pan. If I was to up the concentration to 17-18% so the boils would not last as long would I expect less build up in the front pan? Thanks for input.

[DrTimPerkins]

When you concentrate sap you also concentrate the minerals and organic acids in sap. Thus as your concentration level goes up, the niter formation rate will also go up, meaning that you'll likely not see any reduction in niter formation in relation to the amount of sap you start with. In other words, as your concentrate level goes up, you'll just form niter faster, so a shorter boil won't really change much. Your options at that point are: 1) larger pans (spread out the niter), 2) shorter boils (reduce time for niter to form), 3) switch sides more frequently (can help temporarily) or 4) stop and clean your pans.

[Jeff E]

My experience is the same. I tend to limit my concentration to 14%, so the pan doesn't 'bugger up' to fast. My front pan is reversible, and early season sap lets me run 14% and only 1/2 of the front pan gets the build up, thus reversing works. Late season sap tends to niter up 3/4's of the front pan, even with 10% sap. So daily pan cleaning is needed.

With this late season sap, sugar % is started to drop, but apparently not mineral content. Is there any research showing season long mineral % trends?
My woods starts with thawing trees putting out 1.5% sap, building 3.0%, then slowly declining as the season moves on.

[doocat]

Thanks for the replies. I was hoping for a different answer but that is life. I’ll try a test today with a little higher sugar and shorter boil. If nothing else I’ll have more time to clean the front pan. Anyone ever swap out front cross flow pan midday on a wood fired unit? Just curious!!

[sapman]

I did 17% for 2 hours yesterday on my 30 x 8, and had bad buildup. Wish I'd saved condensate to clean, but guess I'll see how much the reversing does. It won't be enough.

I think it was 802maple who talked about changing cross flows while boiling. Take a lot of courage to pull that off.

One other option is to not finish on the evaporator. Visited large operation last week. They concentrate to 15%, draw off light, finish in 2 x 6 pan, leaving most buildup there. I won't be doing that though.

[802maple]

I was just reading this Tim, I only change pans with a Woodfield evaporator. As long as you don't open the front door it is possible, with oil fired,I get everything ready, right after I take a draw off, I shut it down change the pans, all done in a couple minutes hit the switch and we are off again