The creation of a stained glass window requires from the very beginning detailed knowledge by the manufacturer on the specific location it’s going to have (orientation, height, etc.), since this is decisive specially to analyse the intensity of the light, which will have a direct… impact on the selection of the colours. Prior to that, the designer carries out a series of drafts for the windows. 

The process to create a stained glass window is the following: 

The starting point is always what the client is searching for. Once the theme, the colours, the size and the materials are chosen, a 1/10 scale draft is carried out. The definition of this draft enables to estimate the cost of the stained glass window.

Once the draft is approved, a 1/1 real-size scale draft is developed, which will be the same size as the stained glass window. Therefore, it is then when the lines where the leaded framework will be placed are drawn and the shapes, colours and textures that the different types of glass are going to have are defined. An exact copy of this drawing is then made in cardboard.

The patterns are cut with special-glass-cutting scissors with which, thanks to its double-edged nature, can cut off a slip 1,75mm wide from the perimeter of each template. That space is the necessary one to be able to place the leaded strip between the pieces of glass which will enable them to stay together. With the aid of each one of these calibres each piece of glass is cut one by one. 

Once the glass is cut the edges are smoothed with the aid of diamond blades and it is then painted. The main product which is used for this purpose is the grisaille, a type of paint made of iron or copper oxide which is diluted with water or vinegar and mixed with acacia gum (to enable its better adherence). After that, the pieces are put in the oven at temperatures approximately between 600º and 620º in order to achieve their vitrification. When they have already been fired, they are left to cool down before they are taken out of the oven since if there is a brusque change in temperature the glass can break.

Once this process comes to an end the assembly of the stained glass window takes place, carrying out the composition of the desired shapes with the cut pieces of glass, bringing them together by means of H-shaped strips of lead. This work of assembly starts from one end and slowly reaches the other one. After this process is finished, all the joints are welded with tin on both sides of the stained glass window and, also, all the flanges of the H-shaped strip of lead are pressed tight with a wooden scraper (a process known as bajar los plomos), smoothing them down in order to obtain the perfect assembly of the entire piece. 

To obtain the perfect finish, one must apply on both sides of the stained glass window caulking made of powdered calcium carbonate, linseed oil and turpentine. After that, it is rubbed with sawdust removing this caulking. By doing this, one manages to make the product penetrate within the small gaps between the glass and the rods which when hardened give extra consistency and rigidity to the stained glass window.

To protect the stained glass windows, specially for hinged doors or when the piece is going to be placed outdoors, there are various solutions which are implemented:

Placing metal rods on the back, to which the stained glass window is secured using wires. This is the classic solution which enables lead to be preserved better in time. 

Placing in the back of the stained glass window a 3 + 3 (3mm + 3mm) or 4 + 4 protective glass. One transparent glass and another extra one placed attached to it, which has a transparent plastic protective film on it, are placed. This way when the exterior glass breaks, the pieces don’t fall to the ground but remain adhered to the plastic film between the two protective glasses. This is what is called vidriera doblada (bent stained glass)

There is also a possibility of these glass elements being non-reflective. They are much more expensive but impede reflections distorting the artistic creation of the artisan.