mediums in oil painting

Ok.  My new teacher puts liquin in all of her paintings.  I was not familiar with the product so went to W&N to see what they said about it.  Well, on line there were some pro's and con's.  I know it makes drying faster now.  It has three or 4 different types, up to a gel consistancey.  ( sp?)  Any way.  Laura Robb uses Linseed oil at a ratio of 10 to 1 in an orderless  Gambasol base.  Well, it dries a little quicker but yellows and it not suited to painting whites and there are various thickness of that also.  I like a lush look in painting without it flattening out and I think I found my source on line through W&N.  Now, I'll probably have to order it, since I doubt Hobby Lobby will have any.  I liked the jell.  I don't know if you can use the two mediums on the same painting.  I"ll have to try that, they didn't say.  I do love thick and without just putting lots of paint on a canvas I had no idea how to get this.  Now I have a start. Oil painting gets deeper and deeper for me now.  I was adding a little Linseed oil because Laura recommended it.  Now I find out that what you do on the painting needs to be recorded, so when it needs restored or retouched the expert knows what you used to start their recovery process.  It was said, what a painter uses is the restorer's problem.  I liked that attitude.  I guess with Liquin, you can not remove it or fix what under it.  But it adds high gloss to the painting.  So I guess you could use it for certain area's like my teacher did in one of her landscapes.  Well, nothing of mine will ever need retouching because of it's age, but now I have a little idea of finishes.  I need to add another clear layer to my contemporary painting.  I have been letting it dry for a couple of days, so I don't run the other colors.  Ha ha.. I should have been using linseed oil.  Oh well, live and learn...No age limit.
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Painting and studying

I am listening to a DVD that is in a series.  It is by Quang Ho.  I have 4 DVD's about subjects, Painting the Still Life, Getting Started Basic's and two others.  He is an exceptional teacher, very deep in his observations and eagerness to make learning about painting simpler and faster for me.  Which is great considering my age and starting point.  I recommend them. www.quangho.com.

So, after listening a little to the Basic DVD I am stuck on Tone.  He said without Tone, your color will be wrong etc.  I will have to watch that part many times to understand what he is trying to get across to me.  I understand light and shadow, and some artists didn't use light and shadow, but did use Tone.  I thought it was light and dark, or the three degrees of it usually used in a subject.. like an apple.  So I am a little confused by it.  His DVD of Painting The Still Life will deal with using light and shadow.  So maybe it will help me understand tone.  So, if you draw a chair, you can draw it two ways.  The Chair itself, or what is around the chair to make the shape of the chair.  So, where does Tone fit in?  I am almost finished with my abstract painting and have named it "Summer Reflections".  I have details to do.  I finished my sail boat and learned a lot about painting water.  Yahoo.!!!