Methods of Mop Construction: Polishing Aluminum, Stainless Brass and More

There are many methods of mop construction, but for the purposes of this article, we will concern ourselves with the two main methods:

Open - these are made from whole discs of fabric with a centre assembly of leather washers stapled together or for the smaller types, a stitched centre. These mops present a flexible surface to the work being polished and are generally used for semi-finishing and final colouring depending on the type of fabric used.Stitched - these are used for general purpose and heavy duty polishing where stiffness of mop is required. They may also be dressed with glue or cement and abrasive as described in the previous article. Any type of mop can be stitched but the term usually applies to the type of mop made from assorted pieces of colored or white cotton cloth in various grades. It also applies to the Sisal stapol mops as they are invariably stitched. The mop sections usually have a thickness of approximately ¹/₂" and are concentrically machine stitched and the complete mop is made up of one or more sections.

The method of stitching varies depending on the amount of stiffness required and are generally in three categories: Open stitched - General purpose, close-stitched roughing and scurfing and Very close stitched for heavy duty work.

In addition to the names which describe the fabric or method of construction, mops may also be described as: Brown unbleached: White cutting: Finishing, swansdown, coloring.

The brown, unbleached cloth (calico) mops are in the main used for general purpose polishing and are made from specially woven, long, staple cotton to ensure maximum life.

White cutting mops are made from stiff, white fabric which incorporates a special dressing which reinforces the fabric, keeping the mop stiff and reducing fraying to a minimum. These mops are usually used for initial polishing where a rapid cut is required.

Finishing, swansdown and coloring mops are made from special, soft, unbleached cotton cloth and are used chiefly for the final finishing or coloring operations, using a lime finish or rouge composition. Swansdown is the softest type for the polishing of jewelery.

To prepare a new mop prior to use on a polishing spindle and before applying any composition, the mop should be placed on the spindle and a mop dresser or wire brush held against the periphery as the mop revolves. This ensures true running and levels the face and also causes the threads to be knitted together, giving a smooth, velvet-like surface.

Final coloring and finishing - polishing applications.

Where a mirror finish is required a further polishing stage is necessary. This is usually known as the 'coloring' or 'finishing' stage. For this operation an unbleached calico mop, e.g. B or G quality, is generally used with a calcined alumina based composition such as Cannings Hyfin, Chrome Gloss or Cetem Blue or White, or even a rouge composition. The term coloring as previously stated in the first part is applied purely to the final finishing operation and is not a cutting operation as in the previous two stages. Hence the use of very soft mops.Polishing Steel.

With steel pressings or bright drawn bar or tube it may only be necessary to use a single polishing operation before electroplating, i.e. no abrasive finishing or final coloring stages. For this polishing operation a sisal mop used with an aluminum oxide composition such as Cetem Brown is ideal. A good, bright reflective finishing is generally achieved with this in one operation. If, however it is felt a much brighter finish is required then a further coloring stage, using a calico B mop with a fused alumina compound such as Cetem White or Blue, will achieve a bright, mirror finish. If an abrasive finishing operation is required - start with 90 or 100 grit through 150/180 grit and finish with 220 or 250 grit aluminum oxide.Cast Iron.

Iron castings are generally treated using abrasive belts or scurfs. The grade of abrasive necessary for the initial stage will depend upon the surface condition and may be as coarse as 60 or 90 grit, aluminum oxide being the best abrasive due to its superior cutting abilities. The abrasive operation is carried out as previously' described and for the final abrasive operation a 220-240 or 320 grit abrasive should be used depending on the finish required, the abrasive being lubricated with a good bobbing grease. Where a brighter finish is required the casting may then be polished with a sisal mop in conjunction with an aluminum oxide polish such at Cetem Brown, as for steel. There may be, however, a tendency for the casting structure to be opened up.Stainless Steel.

Stainless steels are usually more difficult to polish than ordinary plain or mild steel but the use of a good quality aluminum oxide polish such as Cetem Brown and a sisal mop will ease the process. Depending on the condition of the metal prior to polishing, an abrasive finishing operation may be required - use only aluminum oxide belts, flap wheels or abrasive dressed scurfs as emery is not hard or sharp enough for this material. Step down through the grit sizes as for steel or cast iron. For final finishing use only calcined alumina such QS Cetem Blue or White with a white stitched mop. Where Cetem Brown has previously been used only a light polishing should be required. If an extremely high reflective finish is required, a final coloring operation may be carried out using Chrome-Gloss with an unbleached calico mop such as B or G quality.Non-Ferrous Metals.

Brass Castings generally require an abrasive finishing operation, using felt bobs or scurf mops dressed with emery or aluminum oxide (when using aluminum oxide it is recommended to use two grades finer). Generally it is necessary to start with 100 or 120 emery and finish with 180 grit. Many components may be finished with abrasive belts or flap wheels. Alternatively Cetem Brown may be used with a sisal mop if the surface is not too rough. After bobbing or abrasive finishing the castings are greased mopped with a Tripoli composition such as Lustre with a hard coloured or white stitched mop. To clear the surface and bring up a high reflectivity the brass can then be finished with a calcined alumina composition, e.g. Cetem Blue or White, on an unbleached calico B mop. As an alternative a rouge composition can be used. On brass with a good initial surface it may be possible to obtain the required finish using Cetem White on an unbleached calico mop without the need for a previous greased mopping operation. Aluminum- and Zinc-Based Alloys.

Aluminum sand castings are initially abrasive finished using belts, flap wheels, felt bobs or stitched mops dressed with abrasive. Use only aluminum oxide grits with a good binder or adhesive as emery tends to embed itself in this material and can cause dragging or tearing of the metal. This is due to the fact the aluminum is an abrasive and clinging material and requires very sharp cutting edges to machine it. After the abrasive finishing operation a bright finishing stage is required using an aluminum oxide composition such as Cetem Brown on a sisal or white stitched mop followed by a final coloring operation using Cetem Blue or White with a soft, unbleached calico G mop. If a satin or matt finish is required, Cetem Brown used with a sisal mop gives a finish suitable for satin anodising. On aluminium castings, where the cast dimpled finish is to be retained but is required to be brightened up, a Fibral satinising mop can be used dry, without any polish. These come in coarse, medium, fine and very fine grades aluminum oxide impregnated grit.Polishing Plated Deposits.

Nickel plated articles from an ordinary dull plating solution require finishing if a reflective surface is desired. For this purpose Peerless polish is used on an unbleached calico mop. Small articles and where deposits are thin a soft Climax or Swansdown mop may be used. Most dull nickel deposits are soft and easily finished to a high reflectivity. Where hard deposits are encountered then a fast cutting white stitched mop may be used, care being taken when polishing corners and projections to avoid cutting the deposit. Alternatively Cetem White, Blue, or Chrome Gloss may be used with a soft calico G mop but not on thin deposits.Chrome Plate.

Chrome deposits should be bright from the bath but can be colored if necessary with a Basil leather mop and Peerless composition. Where chrome deposit is dull or has dull patches Cetem While or Blue should be used on an unbleached calico B or G mop to produce a brilliant surface. This composition may also be used to remove any burnt portions of the chrome deposit and bring up the required finish. For final coloring Chrome Gloss may be used on an unbleached calico B or G mop.Remember, polishing is a skill and the best results can only be achieved with experience and practice.If you have any polishing problems you can rely on Cetem to help you and to give good, sound, practical advice. Cetem use only the best industrial quality materials which cannot be obtained through retail outlets. We also supply to the trade and can set you up if you intend to start your own polishing business. We can supply large industrial size mops, polishing machines, abrasive belt machines, coated abrasives, grinding wheels, loose abrasives - in fact anything used in the polishing industry. Come to Cetem for all your polishing and abrasive materials. We try to supply your every need.