Category Archives: What Cause Pinholes In Welds

What Cause Pinholes In Welds

Hello there! Today we are going to be discussing about pinholes and what causes them to appear in welds. Every welder has probably encounter what we call commonly call as a “pinhole” or sometimes it is referred to as type of porosity. Of course, it would only be right to begin this article by defining all the terms that we will be using here so that you won’t be confused as you go and read until the end. So here’s a short definition of terms:

  • WELDING – (v.) “to join pieces of metal together by heating the edges until they begin to melt and then pressing them together.
    – “to join or bring (people or things) close together
  • WELDER – (n.) “a person whose job is to weld materials together.”
  • PINHOLE – (n.) “a very small hole made by a pin or in some other way.”

Thanks to Merriam-Websters dictionary for these meanings, but I’ll further explain what a pinhole is – just in case you are still confused. If you are a welder, you have most probably seen these in your finished products. Here’s a photo of it:



Can you see the small holes that look like acne scars on some person’s face? There by the glare of the light. Yep, those are what we call as pinholes. These are considered to be a bad thing… In fact, these are a welding defect. Often times, pinholes can be cause by too high welding temperatures. This is because there is a trapped gas inside and when it tries to push out of the surface, it forms into these little holes which aren’t really nice to look at. Seeing pinholes during welding is a common occurrence and problem that every welder has to face. Pinholes are sometimes called as “spherical porosity”. But wait, before we continue – what is posority? We’ve been using the term but we forgot to define it.

  • POROSITY – (n.) “is the quality or state of being porous.”
    – “pore”; “the ratio of the volume of interstices of a material to the volume of its mass.”

Even if a pinholes is considered as a “welding defect”, it isn’t taken seriously because it can be easily prevented. Of course, to be able to know how to prevent something from happening, we must first learn what causes something to happen in the first place. We have gathered the reasons far and wide to find out.

  1. AIR or a draft is getting in the way of the shielding gas during the welding. This could come from fans or overhead fans or air conditioner. It would be an important task for welders to be aware of their environment and not just work work work their asses off.
  2. Sometimes it’s because of the distance between the weld nozzle from the weld puddle. You will have to bring it a little bit closer because if it’s too far away, the amount or volume of the shielding gas may be diminished before it has even reached the weld and because of this, there’s a possibility that the shielding gas will mix with the atmosphere gas which in turn may affect the weld
  3. Moisture is a no no. Just like in wounds, moisture is a no no because it can promote the growth of bacteria.. It is also like this in welding. You can preheat the metal, which is actually a great choice, or you could wipe it thoroughly and make sure that everything is already dry and ready to be used. Oh, and by the way, it would also be a great move if before welding you will be able to take some time to clean the two side of the metal you are going to be welding today.  Be sure that the wire you are going to us is free from rust and any dirt.

    Pinholes can really by caused by this. It’s a simple instruction to remember right? By doing so, you are preventing any new pinholes when you’ve just finished using it.

  4. Double check the welding joint if it is open at the root. If it is open, it could suck the air out from the backside and the unprotected liquid metal can be easily absorbed.
  5. The gas hose could also be a contributing factor. Please make sure that it isn’t kinked or smashed because then it’s ability to think properly leaves on with you. It would be best of your hose is only just right… not too short or not too tight,
  6. It could also mean that the gas flow of your far is high. I coudln’t really find any significant information.
  7. Make sure that the wire you are using has been cleaned. Please avoid contamination especially with paint, oil, grease, glue, and oil. These substances all have the ability to let out poisonous fumes.


Of course if you want a much easier route, you can always go for just using a epoxy, like this one:



With this product, you will be able to do more because you won’t have to be too worried about the knees. You can use this product for you china needs, ceramic, automotive, or metal. You can also use this underwater without any problems. You now have a buddy whenever you feel like fixing the bathroom or the tub to be more specific. This product will be able to help you plug holes and keep them plugged. You will just have to wait for at least 20 up to 30 minutes before it’s all ready. You can buy this product at 7.59 US DOLLARS! It was 22.60 US Dollars before so yes, it really a huge discount on the price.  Here’s a great review about it:


“Excellent product, I had a leak in my car and tried to get it fixed at an auto repair facility. The asking price for the leak was around $600 bucks and that was for diagnostics and repair. I located the leak, purchased this item and fixed it myself. A $600 job fixed with an item that costs less than $10. Talk about highway robbery when it comes to getting your car repaired in a shop!” – Nino Marcelin


So these were the things that caused pinholes in welds, what can you say about them? And also, leave us a comment if you have any questions or inquires. We read our e-mails every day. We’d really love to hear from you and serve you.  If you want to read more articles like this one, why don’t you subscribe to us so you can get alerts whenever we post something new.