Adding extra sugar to wine?

[lakeslad]

Hi all,
i have two demi johns of wine on the brew at the moment,in one i have an orange and apple concentrate mix using a high alcohol making yeast Gv4 ( i think) my question is can i add more sugar to increase the strength/sweetness ( i like desert style wines) and if i do when do i add it and how much?, currently it has been bubbling away quite vigorusly for 3 days,
any help ppreciated.
lee

[oldbloke]

Add it when the initial vigorous phase starts to die back a bit.
If you want sweetness you have to stop the yeast with stabiliser (proprietary, or combined Campden and potassium sorbate) when the gravity has dropped to where you want it.

[Geezah]

A good yeast like that could get you up to 18% abv if you keep feeding it sugar which will get you in to the desert wine figures.
At some point the yeast will give up as the alcohol content is too high, this is when you add sugar to get the desired sweetness.

Or you could do as oldbloke says and stabilise the wine, degass it then backsweeten.

[oldbloke]

A good yeast like that could get you up to 18% abv if you keep feeding it sugar which will get you in to the desert wine figures.
At some point the yeast will give up as the alcohol content is too high, this is when you add sugar to get the desired sweetness.

Or you could do as oldbloke says and stabilise the wine, degass it then backsweeten.

I was thinking more of working out the sugar needed to achieve the ABV and final gravity desired and then stopping the yeast at the gravity, rather than back sweetening.
But I do all mine dry, so for all I know it's simpler to put in the sugar for the ABV, let it go all the way, stabilise, then sweeten.