It is possible to give a different degree of gloss to the surface of metal, plastic, stone, wood or composite at home without the use of professional equipment. A novice master is required to choose the right tool, attachments, pastes and polishing technology.
Materials for grinding attachments
Sandpaper is used for surface pretreatment. With its help, bumps and scratches are removed. It is better to use other materials to add gloss. Finishing polishing is carried out in stages using attachments of different materials:
felt / felt – they are hard, suitable for processing wood and metal at low speeds, removes minor scratches, is suitable for applying protective compounds to polished surfaces;
foam rubber – it can be hard, medium, soft, removes dirt, allows you to process hard-to-reach areas, is suitable for applying abrasive pastes;
sesal – allows you to apply and evenly distribute abrasive compounds;
wool – saves polishes, does not overheat the material, depending on the type of pile (twisted, classic, delicate), it is used for processing and removing scratches, giving gloss;
artificial fur – universal for finishing polishing, long working life;
artificial felt – more durable than natural material, for pre-polishing, removing micro-scratches.
Polishing type: dry, wet, with surface heating
A combined technique is used to make the treated surface shine. During the initial cleaning and removal of large defects, they work dry, and finishing is performed with irrigation. In addition to water, the following are used as moisturizing and lubricating materials:
natural and synthetic oils;
Coolant (cutting fluids);
Dry primary treatment is accompanied by a large amount of dust, but it speeds up the surface preparation process. The disadvantage of this method is surface overheating.
Wet polishing slows down the wear of the grinding attachments, ensures an even structure over the entire surface, as well as uniformity and color saturation. It should be borne in mind that to control the quality of the work performed after each stage, complete drying of the material is necessary.
Heat polishing is commonly used to repair plastics. For this procedure, you will additionally need an industrial (technical) hairdryer. Here it is important to choose the optimal temperature regime in order to soften the surface to the required state and at the same time not spoil the material.
Surface heating also occurs during processing with rotating nozzles. This is one of the reasons why it is so important to monitor the clamping force and rotational speed. With proper control over this process, the material itself does not melt, and its surface is much better processed with a polishing compound.
Where to apply the paste
It is recommended to apply surface polishing compounds to the surface of the attachments. Liquid polishes are transferred with wooden spatulas. The solid pastes are gently applied to the rotating inserts.
When working with liquid pastes, after applying to the nozzle, it is recommended to then gently spread the composition over the entire surface of the polished material. This will ensure an even finish and reduce the risk of polish splashing.
There is also an alternative opinion that it is better to apply solid, liquid and cream polishing compounds immediately to the surface to be treated, and not to the attachment. This is supposedly to reduce material consumption. In fact, this approach does not guarantee the saving of the paste – it will still be absorbed into the nozzle in the process, but the polishing may take a long time.
The general principles for polishing surfaces of different materials are almost always the same. During processing it is necessary:
Clean the surface from dirt: rust, old paint, organic matter.
Remove large scratches, bumps, dents.
Sand the network of micro-scratches left after the initial treatment with the help of pastes.
Add a mirror-like shine using polishes.
Apply a top coat.
Polishing technologies for different types of surfaces
To give shine to different materials, different technologies are used to one degree or another. The reason is the different physicochemical properties of the coatings.
A distinction should be made between the polishing of ferrous and non-ferrous metals. Although the general principles of polishing their surfaces are the same. The process consists of the following steps:
Removal of rust, paint, dirt with disc or cup brushes and sandpaper with grit P22–36.
Elimination of defects using rough grinding.
Removing small scratches from the surface – perform using sandpaper with a grain size of less than P80 and soft wheels.
Mirror polish – use soft leather washers and cotton circles.
Cleaning the metal surface from the remnants of polishing agents, as well as removing oily stains, if any.
The polishing technology is influenced by the shape of the processed surface. Curly objects are processed mainly with abrasive belts, and felt circles are used to polish flat objects .
Polishing flat surfaces is required to start from the center. After conditionally dividing the product into quarters, each of them must be processed up and down. Products with a convex spherical shape are polished at an angle, alternately making movements to the right and left. When choosing the optimal speed and clamping force, you should focus on the following parameters:
steel – peripheral speed is 30–35 m / s, and pressure varies within 1–2 MPa;
aluminum and its alloys – the peripheral speed should not exceed 18-22 m / s, and the pressure should not exceed 0.1-0.4 MPa.
Primary processing of materials can be performed at a rotation speed of about 2800 rpm. During further processing, it is important not only to reduce the speed, but also to adhere to the recommended pressure force. If these parameters are exceeded, at the initial stage, the result can be improved, but the final quality of work may deteriorate. The reason is the increase in temperature during polishing, which provokes some tarnishing of the surface.
To obtain a surface with a roughness of Ra = 0.05–0.12 microns after finishing polishing, it is necessary to use GOI polishing pastes. Their number is determined from the calculation – 100 grams per 1 m². Professionals use combined compositions for polishing. With a lack of practical skills, it is better to use ready-made pasty products.
Polishing painted and varnished surfaces
Most often, this technique is used to remove microscratches from the car body or to give an even shine after painting its individual parts. However, it is also suitable for any other situations – polishing furniture (including MDF-enamel facades), household appliances, freshly painted surfaces. In the process of processing, not only scratches are removed, but also other minor defects – grooves, bumps.
Distinguish between basic, restorative and protective polishing. Work must be carried out in a well-ventilated and well-lit room. The surface to be treated must be thoroughly washed. To add shine, you need three types of polishing compounds:
Usually, when performing work, you can do with medium and non-abrasive compositions. Protective polishing is performed only with the use of non-abrasive pastes.
When sanding surfaces coated with LKSM, it is important not to remove the paint layer, so the pressure should be minimal. The range of rotation speeds is 1000–2000 rpm. Particular attention is required when passing edges and raised edges on the surface. At the final stage, the rotation speed is increased to 3000 rpm. Sequence of work:
primary treatment – remove possible inclusions in the paintwork with the help of cleaners or synthetic clay;
removal of rough scratches – it is advisable to perform sandpaper soaked in soapy water with a gradation of 1500–3000 grit (movements with abrasive sheets must be performed in one direction);
polishing and polishing – the procedure allows you to remove the effects of grinding, these works are performed with foam rubber or woolen circles;
removal of residues of working products from surfaces – using microfiber and a universal cleaner, you need to remove the paste (polish).
To give additional shine and protect against damage, it is advisable to carry out a finishing polish, which is also called protective. It can be done either manually or with a planetary machine. Compositions based on synthetic polymers or special wax are suitable as polishes. The properties and durability of the resulting film depend on the choice of the product.
Natural stone polishing
To improve the quality of processing and reduce wear of grinding materials, work is best done with irrigation. If the constant water supply is difficult, you can use a spray bottle. Usually, manual stone polishing is used to remove scratches from the surfaces of window sills, railings, countertops, steps. Also, using this procedure, you can restore or give shine. Such stone processing is performed in several stages:
grinding – smooth the surface with a large abrasive and remove visible defects from its surface, work is performed in two or three stages with circles with a grain size of 350 to 10 microns (the grain size is gradually decreasing);
polishing – work is performed using polishing powder and liquid, which are combined with abrasives with different grain sizes, varying from higher to lower values;
surface finishing – products are protected and brought to varying degrees of gloss with the help of special means, which are selected depending on the type of stone and the required gloss.
When working with polishing powder, it is important to observe the dosage. If it is exceeded, the amount of abrasive chips will increase. A large amount of powder does not help to increase the speed of stone processing and improve its quality.
A practical application of this method is to remove scratches and scuffs on car headlights. Also, the method is suitable for restoring interior items, household appliances. This procedure also consists of three stages:
rough surface treatment, large scratches must be removed with P400–600 sands;
restoration of the surface and removal of the microcarpine network with abrasives with a grain size of P1000-1500;
finishing polishing and restoration of shine using P2000 + products.
For flat objects, polishers and grinders with any working surface area. To give shine to convex and concave products – nozzles with a reduced diameter. Otherwise, you can cover the surface to be treated with the disc and damage it.
It is necessary to distinguish between sanding wood and polishing it. In the second case, varnish is required. Further processing of the wooden surface consists of:
grinding – perform alternately with P46–170 sandpaper;
application of soil – with linen swabs dipped in the prepared mixture, the entire surface of the tree is covered until a uniform coating is formed (the dried layer must be cleaned with fine-grained sandpaper);
applying the main layers of varnish;
drying of the workpiece – wood with a pre-treated surface must be kept for several days, the exact time depends on the varnish);
polishing – the surface must be wiped with a swab soaked in vegetable oil, cleaned with fine sandpaper and wiped with a clean cloth (the procedure must be repeated three times);
polishing – the surface must be treated with sandpaper soaked in vegetable oil, and then continue the procedure with a linen nozzle soaked in the same oil (repeat several times).
Pre-sanding should be done in at least three stages, changing the grit size of the sanding paper from coarse to finer. After each treatment, wipe the surface with a dry cloth, moisten with water and wipe again with a cloth, and then let it dry completely. This must be repeated after each sanding. Sanding can be considered complete when a smooth, glossy surface appears.
An error at any of the polishing stages will, at least, complicate the processing, and in the most unfavorable development of events, it will lead to damage to the product. Therefore, it is better to acquire basic skills on polishing workpieces, which, in case of failure, will not be a pity to throw away. If this is not possible, you need to practice on the invisible areas of the product.