You have a 24x32 pencil portrait drawn on Canson Paper. But you do not want to put it in a too bigger frame.
I therefore propose you to mat and frame this shetch by creating a passe-partout that will leave visible only the useful part of the art !
Since the drawing sheet is too large ... You are going to hide a part of it using a mat of suitable size.
It will be some calculations for a best adapting, but nothing too complicated you'll see!
- Stiff cardboard for the backing (2 to 3mm thick) you can also work with old bank calendars, it is a good paperboard.
- light cardboard (cardstock) for the mat (do not discard the empty cereal boxes ... it's also great for this)...
- Navy Printed grained Paper for the mat or other patterned paper.
- And usual material for cardboard : metal cutting ruler, glue, scissors, cutter, angle 45 °, bent cutter...
Measure the art you want to frame, these measures will serve you to calculate the dimensions of the mat and those of the window frame.
Here, the portrait is drawn on a Canson paper sheet with format 24x32 ... But you do not want to see the entire sheet, so you will cut a mat that will mask the part of the sheet that not interests you. You will adapt easily the calculations your personal case.
This mat will be cut from light paperboard : it will be also called "passe-partout". For my art, the interested part measures 16cm wide by 23 length ... this is called the mat-window..
Once you know the dimensions of the mat-window, subtract them from the sheet dimensions to obtain the size of the passe-partout margins...
I substract by taking away windowFrame from sheet.
Width: 16 from 24 = 8 ... or 2 margins of 4cm
Height: 23 to 32 = 9 ... or... 4+5
I prefer to share unevenly leaving 4cm above (the same margin on the sides) and 5cm below. It is less embarrassing and sometimes preferable, to have a lower margin a little larger than upper. This emphasizes the idea of depth.
With a cutter, cut a 24x32cm rectangle in the light cardboard. Pay attention to the squareness. Then, by using this first cardboard as a template, trace and cut, with the cutter, a rectangle of same size in the backing cardboard.
The thick paperboard is easily cut … on condition that not pressing too extremely on the cutter: pose the heavy cutting ruler on the part to be preserved, along the reference mark, and cut by spending several times while pressing moderately!
If you have... it's better to use a mat cutter... with blades adapted to slide along a ruler... see these pages about MAPED Tools or LOGAN Tools.
Then draw the window-image ... To do this, take a compass and discard it to 4 cm (the margin): by taking support on the sides of the cardboard and while sliding along those, trace the window to be cut out on 3 sides. Discard now to 5cm and trace the last side.
Cut out the opening of the window, using the heavy ruler and the bent cutter : position your ruler on the reference mark of the window and pass the cutter without too pressing, in several times if it's needed to cut the paperboard completely.
Do not worry if you cut a little deeper into the corners, they will be covered after with patterned paper.
When the mat is cut, you can, if there are "smearings" sand with fine sandpaper.
Place the mat face down on the printed paper that you have chosen. Here, I've chosen a navy blue embossed paper... And draw around 3cm. Cut out the printed paper.
Glue the cardboard face window with a brush and vinyl glue. In general, for a good gluing, it is better to glue cardboard rather than paper ... This will ensure that it does not buckle too ... Now paste the paper and smooth it to avoid any air bubbles!
You can cut the printed paper close-cropped to the external edges (they will be hidden by the final gummed kraft paper).
With a 45 ° angle, open the angles inside the window as on the photo:
Cut now the inside of the window at 1.5 cm from the edges (uses the small ruler as a cutting jig).
You thus form 4 flaps. Fold them back to the back of the passe-partout.
With the back of a blade, mark the folds, at the level of edges, then paste the back of the mat and stick the flaps by checking the angles.
Your mat is finished!
On the backing-board, put the 24x32 portrait, and above, put the passe-partout. Fix the portrait with a tape. You can now temporarily set all with stainless steel tweezers.
If you want a glass pane ... ask for cutting a glass to size ... but it is not mandatory, it can simply keep the art free from dust and other domestic abuses?
Paste now kraft brown gummed tape around your package to close ... just at a distance from 5mm of the edges. It'll just get a nice wooden frame before hanging your portrait.
And why not to build the frame by yourself?