Steps for Doing French/Thread sewing

Aim:-  French/thread sewing on the sections for account book binding.

Materials Required:- Thread, Needle, Sections, Scissor.

Procedure:-  In French sewing, the positions of kettle stitches are marked from 1 to 6 at the spine of the gathered sections. The last section of the book is taken first and kept on the bed of the sewing frame. The threaded needle is pierced into the section through the point 1, taken out from the point 2 and after that the needle is inserted into the section through point 3. Now it comes out of the section through the point 4 and again inserted into the section through point 5. The needle finally cones out of the section form point 6 completing the sewing of the first section.

                The next section (second last section of the account book) is kept on the sewn section precisely aligning at the head and back edge of the first section. The needle is inserted into the section through point 6 and the sewing is done from head to tail i.e. from point 6 to 1. The kettle stitches of the sewing is done from head to tail as in French sewing.

                When the needle comes out from point 1 then a knot is made with the remaining thread of first section’s point 1 to join the edges of the section. In third section, the needle is passed between the last two sewn sections at point 6 and in the fourth section, a knot is made via thread inserted between previous two sections.

                By repeating these steps, we can sew all the rest 10 sections of the account book and at the last a knot is made at the tail at point 1.

Film Assembly

          

Film Assembly

            It is the process of assembling all pieces of film containing the image that will be carried on the same printing plate and securing them on a astolon sheet that will hold them in appropriate/proper position during the platemaking process. The assembled positive films are called a flat. After the flat is prepared it is generally tested on inexpensive photosensitive material to check the image position and to ensure that undesired light reaches the plate. This process is called proofing, if the proof is approved the flat can be placed in contact with a printing plate and light can be passed through the plate to make the plate for printing.

            The pasting/stripping artist uses a variety of tools like T Square, Triangle, Cutting tools, Blades, Knifes to trim films. For greater accuracy an ordinary needle is used to make the masking sheet when laying out a window. Water colour brushes with no. 0,2,4,6 are used. A pair of scissors, a low powered magnifying glass(10x), pencils to 2hetch and 4hetch, pencil eraser, felt tip marking pens for labeling flats are used.

            For negatives the masking sheet that does not passed light to printing plate must be used. The most commonly used are golden rod paper, which blocks actinic light (any light that exposes blue light and ultra violet light sensitive emulsion) because of its colour. The job that requires greater accuracy uses orange or red colour vinyl masking sheet. To positive striping masking sheet and film must pass light in all areas except the image area. Most positive striping is done on clear acetate support sheet or astolon sheet. Opaque is a liquid material used to cover pin holes and other unwanted details on film negative. Red opaque is easier to apply. Old tools mentioned above should be centrally placed near light tables for easy usage.

Imposition: - It refers to the placement of images in the correct position on the printing plate so they will be printed on the desired location on the final printed sheet. Several types of imposition are commonly used. They depends on the following factors:-

1.      The design, folding, trimming and binding.

2.      The type and the size of the machine in press.

3.      The type of paper grain direction.

Masking Sheet: - The position of the image on the printing plate is determined by the film’s position on the masking sheet. Care must be taken in placing the film images on the masking sheet. The masking sheet is generally dark in colour which doesn’t allow light to pass through.

The cylinder line: - It identifies the area of the masking sheet that covers the part of litho palte clamped to the plate cylinder.

The gripper margin: - it is the area of the mechanical gripper hold by the mechanical fingers that holds the sheet during printing.

The plate center line: - This is the center of the plate cylinder for the guidance for plate fixing.