Operation Draw Down Bar Coater and paint draw down

1.1       To lay down the procedure for DRAW-DOWN BAR COATER operation.

2.0       SCOPE
4.0       PROCEDURE


2.1       This procedure applies to Quality Control Department.

3.1       QC chemists to prepare and follow the SOP.

3.2       Head – QA & QC for implementation of SOP.

Casting Paint or pigment-into Films

A paint or pigment film is cast as follows.

4.1       Place an A-4 sheet of paper on the machine’s flat glass surface and over it place draw-down paper and secure it with a paper clip, taking care that the paper's as flat as possible.

4.2       Lock the draw-down bar into place on the appropriate mechanism on the draw-down machine and leave it in the “open” position.

4.3       Using a syringe, draw up about 12 mL of both Control and Batch samples of paint or pigment parallel to each other from the glass jar. Spread this paint or pigment across the draw-down paper, approximately 1 in (2.5 cm) from the top. Paint or pigment will begin to spread slightly on its own.

4.4       Put the draw-down bar into the lowered position so that it touches the top of the paint or pigment and steadily draws it down towards the bottom of the machine, spreading the paint or pigment evenly down the draw-down paper, as shown in Figure. The draw-down should take about 3 s. Do not be concerned if a bit of the paint spills over onto the glass surface of the machine.

4.5      When reaching the bottom of the paper, pick up a draw-down bar remove it from the machine, and place it in a 2-L graduated cylinder filled with mineral spirits for washing. (Discharge the washing water inappropriate manner i.e in a regulatory or legal   manner.) 

4.6       Do not move the machine or paper at all, as this will create an uneven paint or pigment-distribution

4.7       Label the paint or pigment film by writing with a permanent marker on the unused part of the draw-down paper or by placing a separate A-4 sheet of paper beside the draw-down machine, clearly indicating-the batch and film number. Do not attempt to write on the paint or pigment.

4.8       Remove the draw-down paper from the draw-down machine and Allow paint or pigment to dry for 10-15 minutes in the oven

Retrieval of Paint or pigment Film from draw-down Paper

4.9       Carefully peel the paint or pigment film on the draw-down paper and place it on a clean sheet of A-4 paper, labeled with the batch and film number. If desired, this is an appropriate time to label the paint or pigment film itself using a permanent marker.

4.10     Now take the dE and Strength reading in UV Visible Spectrophotometer Premier ColorScan Model No.-SS 5100A and compare the strength with each other.

4.11     Place the film on the draw-down paper in a folder, label the folder, and store it in a clean, dry place.

            SOP:           Standard Operating Procedure

            QA:           Quality Assurance

            QC:           Quality Control                   

6.0       REFERENCE: NIL

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