When I was first told how to enlarge an image for drawing using a grid it sounded complicated, but in reality it is easy enough and is one of the best ways of getting the image’s proportions correct in the final picture. Getting the proportions right is especially important for portraits and for scenes with perspective, like townscapes and buildings.
Artists use an enlarging grid when they have a small sketch, drawing or photograph and they want their painting to be a bigger size than the original sketch. So, for instance, if you have an A4 size sketch and you want your painting to be ¼ imperial size (11×15 inches) or larger, using an enlarging grid allows you to easily and accurately scale the drawing up to fit the paper.
You will need to decide on your grid size, that is how many squares to divide your image into. Larger grid sizes are fine for less complicated sketches but if the grid is too large and the sketch has a lot of detail in it you'll have too much drawing to do in each square. On the other hand if the grid is too small you'll find it difficult to erase the lines when you’ve finished with the grid, and it can get very confusing. There is no definite rule, as the size of your starting and finishing picture, and the subject matter, can be so varied.
You will need: -
• Soft pencil (2B)
• Watercolour or other painting/drawing paper
• Your starting image
1. First select the image you plan to enlarge using the grid.
2. If the image is important in any way then make a paper copy of it by photocopying it, or scanning and printing it if possible. This avoids spoiling the original image by drawing a grid on it.
3. Using a pencil, make a small mark at the very top of the image, directly in the middle, and then mark at the quarters (half way between the middle and the side edges). Then make further marks half way between these marks, effectively dividing the top edge up into quarters and then eighths. Then do the same for the bottom edge of the image. You will then have an equal amount of marks on the top and bottom edges. Using a ruler and a pencil to connect these lines, draw several vertical lines down the picture.
4. Repeat Step 3, but this time mark the edges on the left and right sides instead of the top and bottom. When you are finished marking the sides draw horizontal lines connecting the side edge marks. This will complete your grid. (If you are using our projects the grid on the initial sketch is done for you.)
5. Next use the same method to divide up your watercolour paper. Pencil in the grid very lightly on the paper because you will want to erase it after the drawing is complete.
6. Now draw the sketch from the initial image onto the large grid on the watercolour paper. Do this step by step, square by square. Don’t panic, just start at the top left square on the watercolour paper and draw in there whatever appears in the top left square of the smaller initial sketch.
7. Work across the paper, and then down it, gradually transferring the sketch, one square at a time, from the smaller paper to the larger watercolour paper. The grid will help you enlarge the image while maintaining the correct aspect ratios. Place your drawing and the original picture close to each other so you can glance from one to the other quickly and easily.
When copying the picture, I suggest that you use some spare sheets of white paper to cover some of the image, so you can focus on just a few squares at a time. This can be especially useful for large detailed pictures, where it can become confusing.
8. When you have completed transferring the sketch onto your watercolour paper then all that is left to do is erase the grid from the paper, because you don’t want the grid there in your finished painting. If you have done the drawing in pencil then you will need to take care to avoid eraseing parts of your sketch. If you have done your drawing in ink wait until the ink is completely dry, then it will be easy to erase the pencil grid without any danger of affecting the ink sketch.