GOI PASTE Nr.2 FOR FINE POLISHING OF GLASS, PLASTIC AND METAL NEW 25G 

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GOI pastes - general information.

GOI paste (from GOI - State Optical Institute) - grinding and polishing pastes based on chromium oxide (III), used for grinding and polishing steel alloys (including thermally strengthened), non-ferrous metals, hard plastics and polymers, glass (including optical), ceramic materials and products made from them.

GOI paste is a light green or dark green bar consisting of abrasive chromium oxide powder, organic (fatty) binders and auxiliary substances (activating and intensifying additives). GOI pastes are produced both in the form of bars and in the form of soft (felt) polishing wheels already impregnated with paste.  They are a mixture of chromium oxide (gives a green color, the shade of which depends on the percentage content - 65-80%), as well as solvents and chemical reagents - kerosene, stearin, silica gel and others. There are 3 main grades of GOI paste: coarse, medium (in the pictures) and fine (No. 1 and No. 2). Coarse has a light green color, is the most effective in terms of the volume of material removed, gives a matte surface. Medium is green, gives a clean surface. Fine pastes are dark green and black with a greenish tint, respectively, are used for fine lapping (finishing), give a mirror shine.

Pastes are divided into four categories according to the following classification:

 

 

No. 1 (black paste with a green tint; abrasive capacity 0.3-0.1 μm) for fine polishing, gives the treated surface a mirror shine. Composition: 65-70 parts of trivalent chromium oxide, 1.8 - silica gel, 10 - stearin, 10 - split fat, 2 - kerosene, 0.2 - bicarbonate (baking) soda;

 

 

No. 2 (dark green paste; abrasive capacity 7-1 μm) for fine polishing, gives the treated surface a mirror shine.  Composition: 65-74 parts of trivalent chromium oxide, 1 - silica gel, 10 - stearin, 10 - split fat, 2 - kerosene, 2 - oleic acid, 0.2 - sodium bicarbonate;

No. 3 (green paste; abrasive capacity 17-8 μm) for medium grinding, gives a clean surface without strokes and is used to achieve an even shine of the polished surface. Composition: 70-80 parts of trivalent chromium oxide, 2 - silica gel, 10 - stearin, 10 - split fat, 2 - kerosene;

 

 

 No. 4 (light green paste; abrasive capacity 40-18 microns) for rough grinding, gives a matte surface and is used to remove the smallest scratches left on the surface after grinding with abrasives. Composition: 75-85 parts of trivalent chromium oxide, 2 - silica gel, 10 - stearin, 5 - split fat, 2 - kerosene.

The abrasive capacity of GOI paste is determined by the thickness of the metal removed from a steel plate of 9x35 mm when it passes a path of 40 m on a cast iron plate of 400x400 mm.

Paste typePaste colorAbrasive capacity

 micronscoarselight green  40-18

mediumgreen                       17-8

fineblack-green                    7-1

 

GOI pastes - application.

A small amount of the product is applied to a polishing cloth (soft cloth, flannel is ideal) or to a polishing wheel. Do not apply the paste directly to the surface you are going to polish.

Next, the paste that was applied to the cloth is rubbed against any piece of metal. This is done to remove large pieces of paste that can scratch the surface. Before applying the product, you can rinse the cloth in kerosene or lighter fluid. This will significantly improve the dissolution of this paste.

Then drop a couple of drops of "spindle oil" (industrial liquid oil) onto the polished surface and begin polishing the desired surface.  Periodically, you need to drip oil onto the product, and when polishing, do not make sudden movements with your hands, do not press the surface too hard, because this may not only not remove the existing scratches, but also add new ones. Polish until you get the desired shine.

After finishing work, rinse the product well, preferably in kerosene. If you do not have it, remove the remains of the "GOI" paste with water.