Cleanliness is next to godliness and clean metal is the first step in making god-like welds on steel. There are a lot of ways to clean steel before welding but the method you pick may vary by the steel or job you’re working on. Below we put together our top methods for cleaning steel before welding. These methods will pertain to ARC, MIG, TIG, and even Gas Welding.
- Solvent or Chemical Cleaning- Even if you’re working with fresh, bare steel you still should wipe it down before welding. We suggest using a paint prep or cleaner like our Low-VOC PRE or even straight Acetone. These chemicals will clean the metal, flash off quickly, and won’t leave a residue that could be harmful if welded. A pro tip is to use a lint-free rag to wipe the panel off to avoid anything being left on the surface from the rag.
- Scuff Pads– Woven Abrasive Pads are about the most gentle abrasive you can use when preparing steel to be welded. These pads come in a few different grits and are mainly for cleaning metal that is new/fresh or has already been clean and sat before welding. We like to use these with Low-VOC PRE to assure the metal pores and weld seam are clean and free of any contaminants. If your substrate has heavy paint, rust, or grease you may want to start with a more aggressive method first.
- DA Sander– A DA or Dual Action Sander uses sandpaper of different grits and is really effective for light to moderate cleaning of welding before welding. If you’re prepping a more delicate weld seam like a sheet metal panel you might not want to use an aggressive grinder. We often use 80-220 Grit paper on our DA as a final step before wiping the weld area down with Low-VOC PRE before welding. A pro-tip here is to sand well beyond your weld seam to avoid any contaminants from heating and falling into the weld puddle.
- Belt Sander- A portable belt sander will allow you to get into tight areas; especially the valley of a weld seam and clean the metal without damaging or effecting the metal surround it. In some situations you need to minimize the sanding or access is limited so a mini belt sander will allow you to still clean the weld seam effectively.
- Wire Brush- A wire brush is a good way to clean in tight areas and also to get steel clean before welding without removing material. We often start with a wire brush and Low VOC PRE to clean grease or dirt out of the area we’ll be welding. You can also do a quick pass over the weld seam before welding to get fresh steel if the metal has been sitting in between cleaning and welding.
- Angle Grinder– An angle grinder with a flap disc or grinding stone will remove rust, paint, and other contaminants quickly, but they will remove metal and thin the weld seam. We like to use a flap disc on an angle grinder to bevel weld joints that need multiple passes or for structural welds. You may want to use an angle grinder first to knock of major rust or paint and follow up with a less aggressive method like a DA sander before welding.
- Media Blasting- blasting your project before welding is a great way to get every single square inch clean and fresh virgin steel. This does remove some metal and requires the equipment to blast, but it is the best way to get a part fully clean that is rusty or has paint on it. After blasting be sure to clean the entire part as there can be residue left from the media that may contaminate a weld seam.
While there are many more methods to clean steel before welding these are some of the most common and effective in our experiences. We suggest investing in the supplies to clean steel with these top methods if you’re going to be welding a lot of steel in the future.