THE RIGHT TREATMENT METHOD FOR CLEANING STAINLESS STEEL

When manufacturing stainless steel machines, it is possible that corrosion occurs on the surface. This can happen if the weld discoloration is not removed properly, after grinding, flash rust and damage. When you regularly use stainless steel as a company, you want to treat it as quickly as possible in order to be able to deliver quality to the customer. In addition to external advantages, treating stainless steel also has a physical advantage. As a result, the stainless steel surface is passivated and is therefore protected and prevents corrosion. Stainless steel can be treated by pickling and passivation, which can be done in four different ways.
 

Pickling with a weld seam cleaner

A trusted and safe option within the pickling of weld seam discolorations is with a weld seam cleaner. A weld seam cleaner removes discoloration on stainless steel weld seams easily and quickly without aggressive agents. The device interacts between an electric current and a conductive liquid, so that heat traces and discolorations are easily removed at a high temperature.

A weld seam cleaner is suitable for the simple and quick removal of discoloration and heat traces on stainless steel weld seams without the use of aggressive agents.

Within the weld seam cleaners there are two top brands, namely the WELD Brush and the TIG Brush. The TIG Brush is seen as a brand used worldwide by companies within the food and pharmaceutical industry. In addition, there is the WELDBrush, a very innovative and reliable brand that has built their weld cleaner around the carbon fiber brush. The carbon fiber brush is very unique because of its long lifespan and flexible shape, so that all small corners can be reached. This means that discolorations and heat traces on the welds are easily and quickly removed.

When to pickle with a weld seam cleaner?

A weld seam cleaner is useful for weld seam discoloration and heat traces on small surfaces. The process is very fast because no pre- or post-treatment is required. Because the weld seam cleaner does not use aggressive products, the device can be used on any stainless steel surface and in any room.
 

Treatment process of a weld seam cleaner

Working with a weld seam cleaner can be done anywhere, so the stainless steel machines or products do not have to be moved to a special room, as should be done when pickling with traditional pickling products.

The full length of the fibers of the carbon fiber brush should be dipped in the cleaning fluid ( SCL-255 or SCL-212 ) until fully saturated. The excess liquid is dripped out before the brush is removed from the liquid container.

With the other hand, hold the damp cleaning cloth and lightly and evenly brush the weld or heat trace with the end of the carbon fiber brush in a circular motion.

Use the damp cleaning cloth to carefully remove the liquid residue from the just treated surface so that the liquid is not spread over a wide area of ​​the surface. Repeat the brushing motion, if necessary.

Remove the liquid residue again with the damp cleaning cloth. When the desired result is achieved, spray the neutralizing liquid ( SCL-500 ) on the surface to clean and neutralize this surface.

Clean and dry the surface with the clean and dry neutralizing cloth or with a soft paper towel.
 

Pickling with pickling paste

Pickling with pickling paste is a traditional way to quickly and efficiently remove oxides from welds. During pickling, toxic acids are used that very effectively remove weld discolouration and heat traces.

The advantage of pickling with pickling paste is that it is a cheaper option compared to pickling with a weld seam cleaner. This process creates stains and color differences on the material

Pickling paste is suitable for the simple and quick removal of discolorations and heat traces on stainless steel welds due to the toxic acids.
 

Difference between pickling with pickling paste and a weld seam cleaner

There are a number of differences between pickling with pickling paste and a weld seam cleaner, namely:

• Safety

Firstly, working with a weld seam cleaner is a lot safer, because no toxic substances are used. Pickling paste consists of a number of highly corrosive substances that are bad for health and the environment. 

• Working time

The results of a weld seam cleaner are immediately visible. In contrast to pickling with pickling paste where the processing times are between 10 - 60 minutes. 

• Stains and color differences

When working with a weld seam cleaner, no stains and color differences arise, this does occur when pickling with pickling paste.

• Actions

Cleaning weld seams with a weld seam cleaner is one operation, while pickling with pickling paste consists of several steps.

• Usage residue

After the weld seams have been cleaned with pickling paste, residues are left behind. The residue left behind will cause corrosion. Compared to any residue from a weld seam cleaner that does not affect the surface.

Pickling with spray pickling

Pickling with spray pickling is an effective way to pickle large stainless steel surfaces with weld discolouration and heat traces. The spray stain is quickly and evenly atomized over the surface from a chemical pressure sprayer.

The advantage of pickling with spray pickling, compared to pickling with pickling paste, can pickle faster and larger surfaces.

Spray pickling treatment process

When pickling with spray pickling, you must take the environment into account. It is advisable to do this in a room with a liquid-tight floor. In addition, the released vapor can affect materials in the environment.

We are aware that TIG welding requires working times of approx. 15 – 45 minutes, while MIG welding requires working times of approx. 30 - 120 minutes. To be sure of the treatment times, we recommend that you perform tests with samples to determine the correct treatment time for your stainless steel.

Before you start pickling with spray pickling, you can degrease the stainless steel surface with stainless steel degreaser for a better end result. Make sure that the surface is rinsed with water.

The spray paste is slightly thixotropic, meaning it should be shaken well before use, especially after long storage periods. After you have finished spreading the pickling paste with a pickling brush, the surface should be thoroughly rinsed with a water jet or sponge.
For the best results it is interesting to use a pressure washer . You can also use surface stain , this gives the stainless steel surface a shiny appearance.
 

Pickling with a pickling bath

Pickling with a pickling bath is an economical way of pickling several stainless steel products or large products in one large bath. This method is extremely suitable for companies that want to pickle their stainless steel products on a regular basis. A number of products are added to a pickling bath, such as bath stain, surface stain and demineralized water . This process requires you to consider the different types of content of each pickling product. Wrong proportions can affect the stainless steel more than necessary. Do you have questions about this? Contact us! Core Industrial is happy to advise you on the right proportions.

It is possible to have a pickling bath made to measure, so that your desired stainless steel products can be pickled easily. You can contact us to get advice on the right size.

Bath stain is suitable for pickling several stainless steel products or one large product in one large bath!
 

Treatment process of a pickling bath

Before you start pickling by means of a pickling bath, we recommend that you ask for advice on the correct proportions. Wrong proportions can lead to very negative consequences.

You should also take into account the environment in which the pickling bath process is done. It is advisable to do this in a room with a liquid-tight floor. In addition, the released vapor can affect materials in the environment.

We know that TIG welding requires working times of approx. 15 – 120 minutes, while MIG welding requires working times of approx. 30 - 240 minutes. To be sure of the treatment times, we recommend that you perform tests with samples to determine the correct treatment time for your stainless steel. Treatment times at 35℃ are about half of the times above.

After you have finished pickling the stainless steel products by means of a pickling bath, the surface should be thoroughly rinsed with a water jet or sponge. For the best results it is interesting to use a pressure washer .

For the best aesthetic result you can use surface stain , this gives the stainless steel surface a shiny appearance.

The passivation layer of the stainless steel is very affected afterwards and must be repaired. This takes about three days. To speed up this process, we recommend using passivation agent .
 

Storage times of a pickling bath

The chemicals used in a pickling bath can always be used, but dirt is created after each treatment. This is due to the release of iron particles and contaminants. You can solve this by strengthening the pickling bath with bath pickling concentrate . If you have any doubts, you can always contact us. We are experts in the field of bath stain concentrate and are happy to advise you on the right proportions and quantities.
 

Difference between pickling with a pickling bath and spray pickling

Pickling with a pickling bath is only possible if you have stainless steel products that can be pickled in their entirety. If that is not possible, it is recommended to pickle with spray pickling. With spray stain you can protect certain places by taping it off. On the other hand, the pickling process with a pickling bath is faster because several products can be pickled at the same time.

It is important that the waste water never ends up in the sewer during spray pickling or pickling with a bath stain. We recommend that you contact the local authority.
 

Harmfulness of pickling and passivation

The chemical pickling and passivation of stainless steel is very harmful to humans. This is because highly acidic products are used during pickling with pickling paste, spray pickling and a bath pickling. For this reason, we recommend wearing rubber gloves, a full face mask and protective clothing at all times during use. Follow the safety instructions as stated on the packaging. And always ensure sufficient ventilation when using the product in closed rooms!

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