How To Polish A Knife Blade (A Step By Step Guide)

The ability to polish a knife blade properly and effectively is a useful tool to have. Not only does it prolong the life of your knife blade but it is also an effective way of saving money. However, polishing a knife is not straightforward and can go wrong if not done properly, both from a safety aspect and maintaining a sharp edge for longer.

Polishing a knife properly and effectively can require the use of high powered machinery, which can be quite dangerous if not used properly. Here, we give you a step by step guide in how to polish a knife blade.

Step 1. Clean the blade

To start with you will need to properly clean the knife to ensure that any materials are removed and the surface is perfectly clean. You can use a polishing cloth to remove the basic grime. You might want to use a damp cloth for this first process, but ensure that you dry the knife thoroughly before working on it.

To remove any residue marks or scratches on the blade of the knife, you can use an abrasive scrubbing pad or light fine grit sandpaper. You need to rinse thoroughly after each stage of cleaning to remove any cleaning products or dust from the blade of the knife and also to ensure that the blade is dried in readiness for polishing.

Step 2. Remove rust

Removing any rust is an important stage of the process in order for you to achieve a smooth and sharp finish. You can do this using a store-bought rust remover or you can make your own.

If you are using a store-bought rust remover, you should follow the following steps:

• Follow the directions for the rust remover according to the label
• Place a generous amount of the rust remover on the surface of the blade
• Cover the knife with a cloth whilst the rust remover is working
• You can then use oil to remove the rust remover and to prepare a proper surface

Step 3. Rough Grinding

If you still have a scratch that won't shift or rust that is stubbornly remaining then you can use rough grinding. Here you can use your belt grinder or disk grinder with a light paper in order to remove rough and irregular surfaces from the blade. If the knife is particularly old or rusty, you may want to use a higher density paper with a little more pressure applied.

Step 4. Fine Grinding

Rough grinding can leave deep scratches on the surface of the blade, so in order to polish a knife blade effectively, the next stage is to use fine grinding to smooth the surface further. This is in preparation for mirror polishing your knife. You might want to use a soft disk grinder at this point to create more of a buffing action.

The more that you achieve at this stage, the less you will need to do in terms of polishing your blade later. You can also wipe grease-based chemical compounds such as Emery and Tripoli to help remove the fine scratches that may be left.

Controlling the speed of your belt grinder or belt disk is important for this job. Too fast and you can ruin your blade - we suggest 1800 rpm as a go to speed for the buffing wheel. It's important that the speed is not too high in order that not too much material is removed.

Any faster and the machine becomes hard to control and does not only remove scratches but also removes the blade material, compromising the integrity of your blade. Only if there is significant damage should you consider a faster speed.

It's easy to take material off a blade but impossible to place it back on! Time should be taken and it's better to go slower at first in order that you don't remove too much material .

Step 5. How to polish a knife blade - the final stages

The final stage in order to make your knife look its best is to polish. Considering how to polish a knife blade is dependent on the finish that you want to achieve. Most knife makers want to undertake a mirror polish, which essentially means that you will have a shiny mirror finish on your blade.

In order to get the ultimate mirror polish finish, a stainless steel polishing fluid is often used. It's a relatively inexpensive method but produces a wonderful mirror finish.

You should use a mix ratio of approximately 1:20, using hot water with a metal cleaning solution. Then add the polishing fluid to the mixture and let the two mixes settle for at least 5 minutes.

Place the blade in the solution, ensuring a good coating and then wipe the blade clean and ensure that it is completely dry.

Step 6. How to mirror polish a knife

When considering how to mirror polish a knife, the first process is to wipe down the blade completely to ensure that all residue is removed and the surface is fully polished. A black residue often accumulates at this point after all the polishing, so this needs to be thoroughly removed. At this point, you can either use a clean cloth or run the blade under some warm water.

You'll find more residue if your disk or belt is dirty, so remember to clean it down well after each use - it will save you time at this stage.

Once you've thoroughly wiped and given your blade a final buff , take it outside to check whether you have achieved the desired mirror polish finish. The blade should reflect in the sun and look like a shining piece of jewellery.

Summary

When considering how to polish a knife blade , you should be aware that polishing is actually quite an involved process with several stages - it's more complex than you might think. The most important aspect is to take your time over the process. If you go too hard at it, you will remove too much material.

If you're a beginner to this then the first time that you undertake a knife polishing can be quite daunting but once you have trialled a few times, learning how much friction can be applied and how much steel is removed at different stages, you will soon perfect it. The key to good polishing is to have a good machine to hand, ideally a belt grinder or disk grinder whereby the speed can be controlled and different levels of abrasive material can be used.

If you’re wondering how to mirror polish a knife to get that perfect effect, Soul Ceramics has a range of different belt grinders and disk grinders suited to this job and we can also advise you on the best machines for your desired finish. The best thing to do is to practice using something old that you are not afraid to ruin - in this way you can get a feel of the machine and the process in order to achieve a wonderful mirror polish finish when it comes to the real thing.