- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 20 Mar 2018
Blueprints were first introduced in the 19th century, to allow the reproduction of documents, and in particular drawings used in industries such as construction. Blueprints are generally recognisable from their blue background and light-coloured lines. They create an accurate negative reproduction of the original using a contact print process on light-sensitive sheets. Before this, reproductions were created using a photolithographic process, or by hand-tracing, both of which were expensive and time consuming.
Blueprints were developed in 1861 by French chemist Alphonse Louis Poitevin, who discovered that ferro-gallate becomes an insoluble, permanent blue when exposed to light. If it is coated onto paper (or a similar sheet material such as imitation vellum or polyester film) in an aqueous solution and then dried, (at which point it is yellow) it can be used to accurately reproduce large-scale translucent documents such as drawings.
Reproductions are made by placing the original, translucent document above a ferro-gallate coated sheet in a frame and then exposing them to light. The unconverted coating is then washed away, leaving a stable negative reproduction of the original.
Other photo-sensitive coatings have been developed, along with the similar diazotype or ‘whiteprint’ process (also known as the blue-line process as it produces blue lines on a white background), but it has now been made largely redundant by the development of large format black and white and colour printers. It is still sometimes used to for artistic reasons.
The term ‘blueprint’ can also be used more generically to refer to a design drawing or to a plan for an activity.
 Find out more
 Related articles on Designing Buildings Wiki
- Architectural reprography.
- As-built drawings and record drawings.
- Assembly drawing.
- Component drawing.
- Computer aided design.
- Concept drawing.
- Construction drawing.
- Detail drawing.
- Engineering drawing.
- General arrangement drawing.
- Installation drawings.
- Manual drafting techniques.
- North American Paper Sizes
- Paper sizes.
- Section drawing.
- Shop drawings.
- Site plan.
- Technical drawing.
- Types of drawing.
- Working drawing.
Featured articles and news
RIBA launches a consultation on a new Plan of Work for Fire Safety.
This article offers some basic rules to follow when writing your next specification.
The iconic Mackintosh Building will definitely be rebuilt, board chairwoman confirms.
The machinery used to fashion stone has changed dramatically - and so have the products.
This type of pile provides support to the building, as well as acting as a heat source and a heat sink.
Why investors are adopting the SDGs and why civil engineering could be crucial for delivering them.
Read about all the winners from the London ceremony of CIAT's 2018 Architectural Technology Awards.
How do you find the right stone to conserve historic buildings?
Appointment agreements often include a ‘scope of services’ setting out the consultant's performance on a project.
BSRIA study shows an increase of pre-terminated fibre connectivity.
Director of PiP Architecture explores the application of biophilic design principles.