varnishing help needed!

[newman]

After leaving some of my (water soluble) oil paintings to dry for a few months I thought I'd better varnish them. Being new to the whole oil painting thing I bought a spraycan of windsor & newton satin oil varnish and applied. My problem is that the varnish seems to have sunk in or disapated or something on some areas of the painting, resulting in pics that are really patchy looking; glossy in some places and matt in others. I tried putting on another coat but the same thing happened again.
If anyone could give me any help on
1. what I'm doing wrong so I can avoid the same pitfalls next time, and
2. How to fix the paintings I've messed up
I would really appreciate it.

[dbclemons]

Check out a couple videos on Winsor & Newton's website on oiling out and applying varnish.
http://www.winsornewton.com/resource...os/techniques/

The information is generally sound; although, there can be variables based on how you paint or what was used.
The oiling out procedure will help even out a surface sheen, but should be done before you varnish and you still have to wait for the oil to cure. There's some debate on this method since you're using an oil medium like a finish, which it wasn't really intended for. The main risk is discoloring of the oil which isn't tempered with pigment. Their "painting medium" is made of polymerized linseed oil which is supposedly less yellowing.

[dpaint]

what surface are the oil paintings on? If they're on illustration board or paper that might be the source of the problem since those things aren't usually properly prepared for oil paints.
For oil paintings you must have chemically independent layers between surface, ground, paint and varnish.

[newman]

dbclemons: thanks, I'll have a look at that.
dpaint: yeah, they're on illustration board, but supposedly pre-gessod.
I think that might have something to do with it though, because it sort of looks like the varnish isn't taking in the areas where the oil paint is quite thin.

[dpaint]

yup the illustration board doesn't have enough gesso and the varnish is probably seeping into the board itself in areas causing the uneven effects.

[newman]

balls. Do you know any way of fixing that? Or is it too late for those paintings?

[dpaint]

Let it completely dry and then re-apply the varnish. At some point it should become saturated enough to even out. Not the best solution but I think its too late for anything else. You just wont be able to go back into the painting without a lot of trouble.
Next time if you want to work in oils make sure you follow proper procedure for painting. You might consider switching to properly prepared board or canvas to prevent this in the future. The substrate will depend on if you want a really smooth surface or one with a little texture.

[newman]

cool, thanks Dpaint. I didn't worry too much about the surface when I was painting them as they were only meant to be practice sketches, but they turned out pretty nice so I decided to keep them.
Lesson learnt though! I won't be doing that again.
Thanks for the help.

[QueenGwenevere]

If you use pre-gessoed surfaces, adding a few extra coats of gesso never hurts...

I haven't tried pre-gessoed illustration board (I gesso my own instead,) but I've used pre-gessoed panel and canvas, and the initial layer of gesso does seem a bit thin on those. I always add at least one extra coat of gesso to be sure. I generally add an acrylic underpainting over that, so by the time I get to the oils the surface is pretty thoroughly coated.

[dbclemons]

A properly gesso'd illustration board isn't necessarily going to prevent the problem of an uneven sheen on the oil paint surface. Whether it's on illo board or canvas definetly won't matter since the real probem there is the ground not the support. The issue is related to absorption, and sometimes the ground can be the culprit, so a couple extra coats of an acrylic primer (especially on paper) is good. If you're starting with un-primed paper, size it properly first and go from there.

The biggest factor here is the paint itself and the oil absorption of the pigment. Some types really soak it up, like earth colors, others not so much. That accounts for the patchyness of shine. If it were only the fault of the ground, the effect would be uniform and not patchy. Varnishing can help sometimes, or just raise the shine making it look worse. That's why the oiling-out procedure is recommended.

When I'm painting oils on paper I don't bother with a ground, but just add enough sizing to protect the paper. If you want to use acrylic, get Golden's GAC100 medium and apply 4 coats, or 2 coats and 2 coats primer "gesso."

Sometimes, also, a mat varnish or wax polish can dull down the glossy areas to even things out, but if you've added several shiny coats it'll be hard to fix that way. If you're determined to fix it I'd suggest removing as much varnish as you safely can and start over by oiling out.

EDIT - Re: oil absorption... this site below has a very good listing of pigment information; although somethings are a bit out of date. In the chart of pigment info is listed a column for the oil absorption data. The higher the number the more oil it absorbs and duller it will look when dry.
http://www.artiscreation.com/Color_index_names.html

[newman]

thanks dbclemons, good info, I'll bear that in mind.
Just for clarification though; the level of sheen on the paintings was fairly uniform, it was the varnishing that introduced the patchiness.