Hey Luc ...
I read your Merlot from juice article ... very good. In it you say that 18g/liter = 1% abv. I can't make that match up to any hydrometer charts I can find. It seems you're using a higher resulting alcohol for a given amount of sugar.
Please explain your rationale or point me to the article where you explain this.
I really want to understand it.
Years ago I took all winemaking books I had and started comparing the SG tables.
The least sugar needed for making 1% alcohol was about 15%, the max was at 19.8%.
I compared the SG at certain points in all the tables. Next I compared what they stated how much sugar was at that SG and what alcohol they predicted at that level of sugar.
I published the article on my web-log but it is only still in Dutch. However you can see the table with the SG's derived from the books in that article and that speaks for itself:
http://wijnmaker.blogspot.com/2007/03/hoeveel-suiker-zei-u.html
In the mean-time I have bought another like 20 books, books that were previously not availbale in Holland like US books. An example is what is considered 'the winemaking bible' called Techniques in Homewinemaking by Daniel Pambianchi
In his book he states that at an SG of 1085 you will have 22.2% sugar in the must being 222 gram per liter. He states that will make about 10.6% alcohol. So his figure is even higher as 222 / 10.6 = 20.9 gram sugar for 1%.
Jon Iverson gives on page 214 a brix of 22 at an SG of 1.085.
In his book he states further that half of the brix (approx) will be converted to alcohol.
Meaning 220 gram (22 brix) will get you 11% alcohol.
So 220 / 11 = 20 gram per liter !!!!
Now I think these are out of line.
SG is not sugar content.
Sg is a measurement of all solids suspended in a fluid. So sugar, acid, tannin, color components, flavor components etc.
And my statement is proven by figures given by yeast manufacturers. I had a look at some yeast manufacturers sites and they give far lower figures as Iverson and Pambianchi do. They state that their yeast need as low as 16.7 gram sugar to produce 1% alcohol.
Now I have to work with some figure and therefore I aimed a bit higher. I took the average of all the books I had at that time and used that as the figure to work with, and to be honest it did not prove me wrong.
In the mean time I have seen more tables coming up at the same level I am.
Luc