Here we'll be making a greetings card, but the method used will work for cards, pictures, bottles, jars, in fact anything glass or acetate.
1. If making a card, trim the acetate slightly larger than the size of the window opening of the card. Trace a design and secure it to a table top using the masking tape if you are going to paint onto something flat (acetate or glass out of a picture frame) and fix the acetate/glass on top with masking tape. Or if you are painting onto something 3D such as a storage jar/candle holder etc then tape the design to the inside of the glass with the design exactly where you want it.
2. With a steady hand and even pressure outline all the lines on your design with the out-liner (always make sure all the lines meet, closing any gaps with the outliner or the paint will seep through the gaps). If you make a mistake carefully remove where you have gone wrong with the cocktail stick and kitchen paper or cotton bud in a tiny amount of turpentine substitute or white spirit. Leave to set for 20 minutes before applying any paint.
3. Dip your paintbrush into a pot of glass paint and carefully flood the chosen area with it by putting a drop of paint in the area and gently easing it towards the outline. Make sure that the paint covers the area but does not go over the outline. This may need repeating several times depending on the size of the area. Complete one area before going on to another. Use a clean paintbrush for each colour or clean the brush thoroughly with turpentine substitute or white spirit and drying it with kitchen paper before dipping into a different colour.
4. When finished carefully leave to harden in a dust free area for several days.
5. If making a card, use double-sided sticky tape attach to the back of the window opening of a window card. If making a framed picture either place a piece of white paper behind the glass to give a neutral background making it easier to see the painting or create a background that compliments the painting (the sun-bonnet sue painting has a background made of fabric sewn together to show the grass, hedge and sky and appliquéd floral fabric to show through the painted dress).