Drawing materials and techniques
Drawing materials and techniques
• clipboard/drawing board (with paper, tracing paper, or polyester film fastened with masking tape)
• pencil (test whether HB, 2H, 4H or 6H is best for you, depending on the medium)
• eraser and pencil sharpener
• ruler (scaled)
• set square
• magnetic compass
• extracts from OS maps showing the site and any other available mapped data.
If your site survey drawing is likely to be the only record of your site then it would be advisable to try to use a dimensionally stable archive medium, such as polyester drafting film, a material that maintains its original dimensions in conditions such as rain. Drafting film provides a semi-transparent, waterproof surface and you can edit pencil lines easily with an eraser, as you would on normal paper.
Drafting film is a relatively abrasive medium and it is best to use hi-polymer (4H–6H) lead pencils to achieve clean lines that will not be accidentally wiped away. Well-sharpened or propelling lead pencils are good for scale drawings. They make a clean, sharp line and don’t smear easily.
Media for drawing
Paper comes in different sizes and qualities, ranging from newspaper grade up to high quality and relatively expensive paper sold as individual sheets. Papers can vary in texture, hue, acidity and strength when wet. Cartridge paper is the basic type of drawing paper sold in pads.
Tracing paper is named as such because an image can be traced onto it. When tracing paper is placed over an image, the image is easily visible through the tracing paper. Tracing paper can be used, for example, to experiment with phasing over a half-finished drawing, and to transfer a design from one sheet to another.
When choosing your media consider the circumstances in which you will be using it: paper and tracing paper are not much use in a damp or rain-affected environment, and are not dimensionally stable, that is the ability of a material to maintain its essential properties or original dimensions in perpetuity.
Using polyester drafting film gets around the problem of weather prejudiced surveying as it is a waterproof medium. Drafting film is anti-static and accepts ink or lead, erases cleanly and provides excellent dimensional stability. Film won’t tear or discolour and is excellent for archaeological and architectural applications; it is highly translucent for tracing, gives sharp reproductions and is compatible for use with laser printers and photocopiers. Polyester drafting film is available on rolls or in single sheets at various sizes. If you are involved in a SUP registered project that involves survey work we can provide you with a limited supply of polyester drawing sheets.
Using graph paper
With graph paper, you can easily make and control the scale that you choose to use for your drawing by marking out the distances, or ‘scale metres’ on your paper. To recap, if the scale you choose is 1:50, then 20mm on the graph paper will represent 1 metre (1,000mm) on the building. If you want your drawing to be at a scale of 1:100, then 10mm on the graph paper will represent 1,000mm on the building, and so on. If you are using drafting film you can use it as an overlay and transcribe all your data directly onto it.
The width of a pencil lead
Remember that when using a scale of 1:100, the drawing will only be accurate to within 5cm because the pencil lead will probably be up to 0.5mm thick. At a scale of 1:100 the pencil line (0.5mm) will represent 50mm (5cm). So the fine accuracy of your measurements is not absolutely crucial. As the scale of a plan decreases, so the details that can be included in the drawing decrease. At 1:200, any feature measuring less than 20cm will be too small to draw on the plan, because each pencil line will represent 10cm. At 1:500 this applies to features of approximately 50cm in size.
Three basic types of line are used in survey drawings: thin solid, thick solid and dashed. A thin solid line is the most used and describes the outline and all features of the building. A thicker solid line is used in plans and sections to show where the walls, floor, ceilings, roofs, stairs, etc of a building have been bisected to create that view. A broken line is usually used in plans to represent an unseen structural feature above sill height such as a balcony or gallery.
Colour, detail and texture on scale drawings
When you do a scale drawing, you should consider the level of detail as though you were looking at the building from a distance. This imaginary distance affects colours and textures. If you look at a building from a distance, you may not be able to make out the joints between the brickwork or where one roof tile ends and the next begins. Door handles and other fittings may just appear as amorphous blotches on a front door and something similar also happens to colours. As you move further away from them, the less distinct and vibrant they become, like mountains viewed from a distance, or houses and fields viewed from an aeroplane window. The amount and sharpness of detail you show, and the brightness of colours on the drawings, depend on the scale of the drawing. You cannot show a lot of detail on small-scale drawings.
Bright colours which might look fine on a 1:50 elevation of a house may look garish if they are used for the same house shown at a scale of 1:200 and you should consider the use of colour carefully before applying it. If you don’t want to apply colour to an original drawing you could produce copies or even a colour overlay/underlay.
Tain, Castle Brae, St Duthus’s Collegiate Church, Caretaker’s Cottage. Extract from a late Victorian architects plans -West Elevation; Section on Line A-B; (original scale 1/16”:1’)
Signed and Dated “A Maitland & Sons, Architects, Tain 22/8/1884”
Historically, colour was used according to standard conventions in plan, elevation, section and detail drawings. One reason for this is that it provided a vivid and uniform understanding of a structure that could not be communicated any other way at the time. Architectural drawings made in the later 19th and early 20th century used the following conventions;
- Brick red (pale on plans and elevations, dark on sections)
- Stone yellow ochre (pale); indigo used for sections and details
- Concrete grey
- Wood sepia (pale on plans and elevations, dark on sections)
- Iron and steel dark blue (pale on plans and elevations, dark on sections)
- Plaster light yellow ochre used for sections and details
- Tiles (floor) red
- Tiles (roof) red brown (pale on plans and elevations, dark on sections)
- Slate grey green
Drawing symbols: structural features
A specific set of conventions and symbols is used to depict structural features at various scales; the most relevant to the needs of the surveyor are illustrated below.
A specific range of symbols are used for drawing buildings, particularly if they are ruinous or appear as archaeological features. The larger the scale, the morerepresentative the drawing can be; the smaller the scale the more generalisation as the examples above show.
Drawing symbols: structural features
A specific set of conventions and symbols is also used to depict natural features at various scales; the most relevant to the needs of the surveyor are illustrated below.
Drawing conventions used for mapping natural and other topographical features.
Always remember to include the following items on your sketch or field survey: (1) drawing title, (2) your name, (3) the date, (4) the scale, (5) National Grid Reference if appropriate, (6) North point. If your drawing is one of a number of different drawings it would be useful to number them in sequence.
To emphasise the horizontal and vertical dimensions in the outlined edges of a building use a bold line. A thick profile line with a thin inside line lends more massive appearance to a building drawing. By overlapping lines you can also create a sense of height or depth to an otherwise flat drawing.
Two examples that use different line weights to suggest height, depth and phasing in two-dimensions
You can add texture to a drawing of a building with a pitched roof to create a three-dimensional quality. The direction of the lines can indicate the actual building materials and the direction in which they were laid or indicate the slope of pitched surfaces. Ideally the sun sides of the roof should have a lighter texture than the shaded sides or you can simply leave them unshaded.
Two examples of different shading effects that can also be used to indicate slope, textures and materials.