How To Paint Glass
I created this illustration by using Corel Photo Paint, and one like it using PhotoShop. The flowers were added from my living room, and the glass urn originally was a plaster planter from my front door entrance. If you have one of these programs or a similar one, I'll show you how I did this. If you use some other medium, it can still be done: A paint sprayer will work, and so will oils or tempera. The outline of the urn can be done by turning your paint into a transparent glaze with their associated thinning element.
I'll start with a simple drop of water, to teach the basics. Draw a circle, then shade it as if light were coming from the bottom (see Figure 1). Next, put a shadow under it. A short and less fuzzy shadow will help the drop to look flattened. A larger, soft shadow will make the drop look more spherical. At this point, the circle will look like a button illuminated from below, or it will look like a crater or dinner plate with tiny ridges illuminated from above (see Figure 2).
Now, all you have left to do is add the bright highlights to instantly and magically turn this button into a transparent drop of water! Adding highlights over a dark area puts implied space between the surface the drop is sitting on and the highlight (Figure 3). If, at first, your rendition doesn't look like a drop of water, look away, then squint when you look at it again. Because you know how it was built, it may reluctanly transform itself. But others, not knowing how it was built, will instantly see a drop of water.
You're done, unless you want a different type of highlight, which is shown in Figure 4. Its your choice, whichever works for you.
Now, for the main subject of the composition: I started with a rose my wife had placed on our microwave oven (see Figure 5). A picture of something on the table is all you will need at this point in time, with nothing else done to it for now.
Next, find something to serve as the glass vessel. I took a picture of a gray pressed-paper planter found next to my front door. Then I made a negative of it. You can do this in PhotoShop or CorelPhoto by doing a reverse in Curves. The highlighted areas became dark and the shadows became light, just like we did with the two drops of water above: This is the key procedure that will make the urn look like glass. (A planter like the orange fiberglass one to the right could be photographed, turned to a black-and-white photo, then reversed.) Next, I outlined the planter in my reversed photo to get rid of the background, then I added the white highlights like we did on the buttons above. See Figure 6 to see the result. This urn was tweaked a bit to enhance the effect, but it's not entirely necessary to do this. The planter has now been converted into a glass urn.
We're almost done. The urn is copied and pasted on top of the rose. Make the urn's level a bit transparent for the moment so you can work with it. Size the urn so that it fits around the rose. Next, erase the stems that do not fit into the urn (if the flower is on it's own level), or use the clone stamp to copy the table cloth over the vegetation.
Next, use a very soft and low-pressure eraser to get rid of the middle areas of the urn. This will allow the rose to show through, and give the urn a transparent effect. You could even do an even lighter eraser for the edges of the urn so that they might appear transparent too.
To make the rose look like it is peeking out from behind a glass rim, I created a white panel in front of it on another layer, its top in line with the top lip of the rim closest to us. Then I reduced it's opacity to a very small number like 3or 6. Then I used a soft eraser to erase everything except the top part of the panel. The white area fades from what you can see, to nothing somewhere on top of the rose's stems.
That's it! Tweak your work, step back a few times and make corrections as directed by the artist within, and enjoy showcasing your work!