Brodhead Pietenpol Association

Original Posted By: gus notti
Subject: Pietenpol-List: Power Coating (was Center Section progress)I'm usually a lurker but wanted to come out on this one. The statement about powdercoating hiding cracks is a myth that has been floating around for years.I've lots of powder coated parts on many applications including modified motorcycles.I recently had a powder coated bracket re-welded that cracked under the powdercoating. If anything the powder coating makes it EASIER to see the cracks. Itis very unforgiving of relative motion of the part under it. It's soft enoughthat the edges of the powder coat quickly wear against each other and makethe crack look BIGGER than on the actual part. If the powder coat is anythingother than black, it gathers debris from the motion of the crack and show a darkline too.Andrew>One thing to keep in mind about powdercoating is that, while it is very >durable, it is also flexible, and can sometimes hide cracks in the metal >underneath the paint.________________________________________________________________________________Date: Thu, 10 Nov 2011 13:59:27 -0800 (PST)

Original Posted By: "K5YAC"
Hi Andrew,Lurk no more. You're out of the closet now.In response to your comments, I don't think that it is fair to simply say that"powder coating hiding cracks is a myth". It is very possible for powder coating(and some other finishes) to hide cracks in the underlying metal. There aremany different types of powder coating (polyester, epoxy, hybrid, etc.), allwith different characteristics, including flexibility. Some powder coatings maycrack where others would not.In general, powder coating is applied in greater thicknesses than traditional paintfinishes, and one of the selling features of powder coating is that it willhide many flaws. When the powder cures, it will flow, and has the ability toclose small gaps. For example, it is possible to do a less than sufficient weldingjob on a motor mount, and then have the motor mount powder coated, andthe substandard workmanship can be hidden by the powder coating.In general, powder coating is a fantastic product. In addition to being environmentallyfriendly, it also produces a finish that is almost "bulletproof", andit has the ability to make some objects look better than they actually are. Iplan to use powder coating for some of the metal parts of my Pietenpol. But whenit comes to a critical structural element like the motor mount for my homebuiltaircraft, I will choose to use a different coating system.Bill C.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Power Coating (was Center Section progress)

Original Posted By: Matt Dralle
Andrew, how could you know for certain that powder coating doesn't hide cracks?I mean, how far does a fracture need to propagate before evidence shows throughany type of coating? I'm not saying that powder coating is good or bad one way or another, just wonderinghow anyone could be certain that your theory holds true in all cases. Imean, when you say it is a myth, you suggest that the idea is completely false.In other words, you are absolutely certain that fractures or cracks are readilyevident through a powder coated finish... always? Hard to believe. Not trying to sound abrasive, just curious at how anyone can be certain about thisone in all instances. Oh, it is definitely not a certainty that powder coatingwould absolutely hide an underlying flaw, but the fact that it is more ableto do so than thinner, hardened acrylic urethane or enamel is likely true,which was Bill's suggestion. My guess is that this "myth" will continue to floataround for a while longer. I can certainly see where a thicker, more durableand semi-flexible finish could hide underlying flaws or failures. Some comments from a company named E-Tech Powder Coating...Powder coatings are very flexible, and can flex with the metal as the spring, coilsand recoils to its stationary position. Also epoxy, acrylic and hybrid powdersprovide excellent adhesion and hard-ness for improved resistance to chipping,abrasion, corrosion, and chemicals; and its flexible enough to be formablewithout cracking.Powder coating offers the consumer a superior finish while adding many performanceproperties such as excellent resistance to corrosion, chemicals, heat, impact,abrasion, UV rays and extreme weather conditions. Not only is powder coatingexceptionally tough and impact resistant it can easily withstand flexing action.There are several more comments about durability and flexibility, and while thisis much preferred in many finishes, I wonder if it might not hinder proper inspectionor early detection of damage on the critical parts that Bill speaksof. Not an expert on the subject, just considering the possibility that it may notbe a total myth.--------Mark ChouinardWings, Center Section and Empannage framed up - Working on FuselageRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Fri, 11 Nov 2011 00:13:01 -0800