Whatever your material is, nobody likes their finished product to have little holes in them when they aren’t supposed to be there. These little holes are commonly referred to as “Pin Holes”. A pin hole is basically just a small hole that can be cause by a pin through an easily penetrated material such as a fabric or a thin layer of metal. There are some cases wherein a pin hole is intentionally created there. An example for this would be optics pin holes, which are used as apertures to select certain rays of light. This is used in pin hole cameras to form an images without the use of a lens. Sometimes, pin holes can also be found on produce packaging. The purpose behind this is to control the atmosphere and relieve the humidity within the packing.
However, if a pin hole is in a place where it isn’t wanted, then it could be causing you more harm than good, especially when it comes to manufacturing processes. An example of this would be in the assembly of microcircuits. Pin holes in the dielectric insulator layer coating the circuit can cause the circuit to fall. When it comes to textile, sometimes you have no choice but to use pin holes, but you must always remember to somehow cover them up because nobody wants a blemish on their masterpiece. And I’m sure the wearer would appreciate having no tiny holes in her dress.
Depending on the fabric, there are lots of easy ways you could try in order to get rid of those pin holes.
- If you want to remove pin holes from a cotton fabric material, the first thing you should do would be to dampen the fabric by spraying water on the spot where there are pin holes seen. Get a cup of coffee or toast some muffins for you will need to leave the fabric along for a bit. The rationale behind this is to allow the fibers to rest, relax, so they can spring back into position. There are times wherein a steam iron would do, but the spraying method seems to work on larger looking pin holes. You could try though, cause it won’t really hurt.
- If you want to remove pin holes from silk and polyester fabrics, then the first thing you should do would be spray a little water on the area then steam press from the back of the piece. Not on the front. And please, always use a pressing cloth and do not forget to set the iron between low to moderate temperature. Find a hidden area where you could test it first, especially when it comes to silk. I greatly discourage putting pins in areas were they could be visible later. Wiggle the threats with your finger nail to encourage them to go back to their pre-pin position. If it’s washable, go and wash it then let it dry naturally; then gently steam press.
- If you are into welding, you should understand that seeing pinholes in your finished products is a big no no. Sometimes, pin holes can appear in your material, and they are common when you are doing MIG welding. Some long time welders say that these pin holes are caused by the gas you use, whether it’s too low or too high. Poor gas coverage or contamination are mostly the ones who are cause an increase in porosity of your material. Oil, paint, and rust are some of the common causes of the issues. However, there are also those times wherein it comes from the base material that you are using. Make sure that the material you are using isn’t some cheap casting with a lot of impurities.
Since most of the causes is from the gas, you should always make sure that you double check the hose if it’s pinched, a kinked MIG gun or a blocked nozzle to be easier to understand, if you are doing a bad angle for the gun… and it could also be a sign that you are already running out of gas and should reload.
What can you do about this? Well, since the cause is sometimes poor gas coverage or usage, then the rational thing to do cope with this would be to increase gas flow in order to displace all air from the weld zone. Make sure to decrease excessive gas flow to avoid turbulence and entrapment of air in the weld zone. You should also be sure to remove any spatter build up in the nozzle, and eliminate any leaks in the gas line. Hold the gun at the end of weld until the molten metal solidifies.
You may also use welding grade shield gas. Keep in mind to only use clean and dry electrode. Be sure to also remove all grease, oil, moisture, rust, paint, and dirt from the work surface before you begin welding. It would be good if you are able to use highly deoxidizing electrode.
Reduce voltage, and then reduce electrode extension.
- SOME OTHER TIPS:
– Maintain the proper arc length
– Use proper welding current
– Increase gas flow rate and don’t forget to check gas purity
– Reduce travel speed
– Properly clean the base metal prior to welding
– Properly maintain and store electrode
As you can see, there are ways to prevent pin holes from happening in the first place. In any case, that you notice the holes after you finished welding, no worries there’s still one more thing that you can do. You can buy a epoxy. I highly recommend J-B Weld 8262-S SteelStik Steek Reinforced Epoxy Putty Stick. You can get it for as low as 5 USD. It is able to repair anything made of metal, and it works on both wet and dry surfaces. It doesn’t matter if it is submerged in gasoline or water. If you are worried about aesthetics, you won’t have to be since this epoxy can be drilled, filled, tapped, machined, and painted. You can put it in place for 5 minutes, and in one hour the metal with defect is cured.