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Zinc coating is applied in steel to protect it from oxidization and corrosion. This process is known to us as galvanization.
Zinc coating must be stripped from steel before welding it. Otherwise, it will contaminate the environment by releasing toxic fumes.
In this article, we will learn how to strip zinc plating from steel in easy way.
Zinc plating can easily be stripped from steel by using acid solutions. However, we advise not to try this at home without expert’s supervision. We will show you two methods that can remove galvanization from steel.
Different Methods of Removing Galvanized Coating From Steel
Method 1: Vinegar Method
You can easily strip galvanization by soaking it in vinegar. This method is the easiest way to remove galvanization.
- A plastic brush
- A small glass bowl
Soak It in Vinegar
You need to fill the small glass bowl with vinegar. Then you need to soak the galvanized steel in the bowl.
Wait for the Steel to Shed Zinc Plating
As vinegar is a weak acetic acid, it will take a long time to shed zinc. You will see bubbles in the glass bowl. After a while, there will be lumps of zinc that are coming out from the steel.
It will take at least half an hour to shed zinc from a 4cm steel. So, if the steel is bigger in size, you need to soak it in vinegar for a long time or you may switch to stronger acid such as muriatic acid method. (method 2).
You need to check multiple times until all of the zinc plating comes out. Then you need to take out the steel piece from the bowl. Next, you need to brush it multiple times.
After brushing, soak it in fresh water and rinse it few times for better shine.
So, by applying these 4 easy steps, you can easily remove galvanization. The major drawback of this method is, it takes a lot of time. Thereby, it is a useful and simple method only for small objects.
Method 2: Muriatic Acid Method
Muriatic acid is also known as hydrochloride acid (HCl). It is prepared by dissolving about 30% HCl in water. It can be purchased from hardware store.
Muriatic acid is comparatively stronger and works faster than the vinegar. However, it is very reactive and dangerous. Thereby, do not try this method if you are not an expert. In any case, necessary precaution is mandatory.
- Muriatic Acid.
- Baking Soda.
- 5 Gallon Bucket.
- 3 Gallon Bucket.
- Corrosion Resistant Plier.
- Garden Hose Pipe.
- Paper Towel.
- Protective Eyewear (Goggle).
- Protective Shoes.
- Chemical Resistant Clothing.
- Face Mask.
Note: If your metal still is rusty then use a rust converter to clean it before start removing galvanized coating. It will help you do this process more faster.
Take Necessary Precautions
Put on latex gloves, eyewear, boot, clothes and mask before preparing the solution. Use pliers to touch the steel after galvanization process. Do not touch the steel or the solution with bare hands.
Do not spill any acid in your clothes. Use only industrial grade plastic bucket. Most importantly, use well ventilated workspace to perform the method. The acidic solution should not be near any heating source or metal.
Also keep the solution away from children and pets.
Mix the Solution
Mix water with muriatic acid in a 3 gallon bucket. You should not combine more than a gallon solution at a time. The ratio of acid and water in your solution should be 1:10.
Suppose 1 gallon of liquid equals 16 cups of water (according to your Pyrex). In that case, add 14.4 cups of water with 1.6 cups of acid.
You need to add water in the bucket first. Then you may add acid. Otherwise, it will lead to harmful reaction and may melt your bucket by producing heat.
Place the Steel in the Solution
Use plier or any corrosion resistant tool to carefully place the steel item in the solution. With the contact of the acidic solution, it will start to fizz. After placing it in the solution for few hours, carefully take it out with the plier.
If the zinc coating exists by then, you may need to submerge it in the solution again and wait for one or two hours. Different materials may produce a different result. Make sure to determine the steel and identify the differences, especially in cases of cast iron or cast steel.
Take the Steel Item Out
Take the steel item out of the solution. Wash it with water using the hose pipe. Then swab it using a towel.
Congratulations! The steel item is now free from zinc coating.
But, you are not done yet. You need one more thing to do. You need to neutralize the acidic solution and dump it safely.
Take out the other bucket (5 gallon bucket). Add 3 gallon water in it. Then add sufficient amount of baking soda (also known as ‘sodium bicarbonate’). At this point, you may carefully apply the muriatic solution into the 5 gallon bucket.
With the contact of baking soda, the solution will fizz. It will continue to fizz until the neutralization process is complete. If the fizzing process continues after a while, you need to add more baking soda.
After the vibration stops completely, the neutralized solution can be disposed safely.
Small amount of neutralized solution may be disposed in your sewer using plenty of water. If the amount is large, than contact local state agency to evaluate that the neutralization process was done perfectly. Then you may dump the solution safely.
That’s it. Hopefully, now you know how to remove galvanized coating from steel. If the process is right, you might be able to customize the steel yourself, such as hardening a mild steel. It’s time to go and try yourself. Cheerios!