Powder coat dilemma
12-10-13, 05:41 PM
#26
Mr. Anachronism
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A tubular structure with possibly ornate reinforcements and their sharp edges and the possible multitude of braze ons that have often plenty of sharp edges and small cavities, all surfaces not easy to apply a nice uniform thickness of powder to be melted into a film. Also, consider what this fluid does in its semi molten state, it pulls away from sharp edges reducing the final film thickness there. Physics cannot be avoided. Experienced applicators of powder coat materials can make up for some of this deficit by adding material at problematic regions, a second layer will help even more.
Note I stated my experience was with single stage applications.
What I have found is that upon chemical stripping of all the single stage powder coat jobs on bikes I have had done or purchased over the years there is plenty of corrosion propagating from this thin film areas that was NOT visible from the outside looking in.
On a lugless bike with carefully radiuses edges and few if any braze ons one will have a better outcome.
A two stage application will by definition have a better chance of corrosion protection due to the additional film thickness.
With either approach, powder coat will obscure detail such as serial numbers and engraving, lug windows more, and more often than a wet paint job.
Note I stated my experience was with single stage applications.
What I have found is that upon chemical stripping of all the single stage powder coat jobs on bikes I have had done or purchased over the years there is plenty of corrosion propagating from this thin film areas that was NOT visible from the outside looking in.
On a lugless bike with carefully radiuses edges and few if any braze ons one will have a better outcome.
A two stage application will by definition have a better chance of corrosion protection due to the additional film thickness.
With either approach, powder coat will obscure detail such as serial numbers and engraving, lug windows more, and more often than a wet paint job.
Guilty as charged.
Might have been corrupted some by a favorite author... a dude named Rob Bell.
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12-10-13, 06:00 PM
#27
Senior Member
Here is a Wikipedia quote
[h=2]Types of powder coatings[edit][/h]There are two main categories of powder coatings: thermosets and thermoplastics. The thermosetting variety incorporates a cross-linker into the formulation. When the powder is baked, it reacts with other chemical groups in the powder to polymerize, improving the performance properties. The thermoplastic variety does not undergo any additional actions during the baking process, but rather only flows out into the final coating.
The most common polymers used are polyester, polyurethane, polyester-epoxy (known as hybrid), straight epoxy (fusion bonded epoxy) and acrylics.
[h=2]Types of powder coatings[edit][/h]There are two main categories of powder coatings: thermosets and thermoplastics. The thermosetting variety incorporates a cross-linker into the formulation. When the powder is baked, it reacts with other chemical groups in the powder to polymerize, improving the performance properties. The thermoplastic variety does not undergo any additional actions during the baking process, but rather only flows out into the final coating.
The most common polymers used are polyester, polyurethane, polyester-epoxy (known as hybrid), straight epoxy (fusion bonded epoxy) and acrylics.
12-11-13, 12:04 AM
#30
Senior Member
12-11-13, 06:58 AM
#31
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Back in the day I was doing desing work, we powder coated our front and rear castings of aluminum because the instrumentation was a mobil design. Testing of impact, abrasion etc of powder coat showed a 40x resistance to damage comparted to the best wet paint application like Imron. PC was fairly new back then and was only avalialbe with a process of 400 degree ovens. Today you can do it in 250 degree ovens and in your own oven. That was over 30 years ago and I have not kept up with the developments of PC since. I assume it is still used for the same reasons, plus the ease of application and compliance to environmental regulations along with cost effectiveness. Back then there were issues of masking too which don't apply today.
12-11-13, 12:22 PM
#32
Senior Member
What the OP can do is try to find somebody doing Electrostatic Painting, that paint is not baked. My old miyata pro had that finish, the nice about it is that is not baked, second the finish gets almost as hard as appliances finishes and pretty much you can paint over chrome plating, sure you guys have seen several japanese frames that are chromed under it, that this has to be Electrostatic Painting.
The other advantage is that the layer of paint is quite thin as regular wet paint, so any frame embedded in the frame or fork will be nicely kept.
For the record never seen anybody doing this for bikes so could be a challenge to find a guy doing it.
The other advantage is that the layer of paint is quite thin as regular wet paint, so any frame embedded in the frame or fork will be nicely kept.
For the record never seen anybody doing this for bikes so could be a challenge to find a guy doing it.
12-12-13, 10:33 AM
#33
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Imron is indeed great stuff, when properly catalyzed and when the surface is prepared properly beforehand. Such was not the case with my Trek 600, which had to be stripped and powder-coated thanks to an extensively chipped and scraped Imron paint job.
The prices for Imron paint jobs have everything to do with the labor-intensive nature of the preparation and paint process, and with the toxicity of the isocyanate cross-linkers used (requiring PPE for the paint shop workers). Preparation for powder coating is a lot less of an involved process - you need racks, an applicator gun, the powder itself and a suitable large oven & that's it. No solvent handling/recovery, no problems with overspray, few toxic effects (unless you breathe it in directly). The powder itself doesn't require clean-room conditions in order to adhere properly.
Steel didn't melt at WTC 1, WTC 2 or WTC7 for that matter. It didn't have to melt. Because it softened instead, losing over fifty per cent of its original strength in the process. Thermal expansion was also a factor, resulting in the sagging of the affected floors (ex. WTC 1&2) and the loss of the anchorage for the horizontal column support members (particularly in the case of WTC7). Fire protection coatings weren't up to modern standards, which did not help - nor did the presence of copious amounts of papers, files, furniture, rugs, and other combustibles (particularly in WTC7, which burned viciously for hours). It also must be remembered that the jet liners punched through a number of support members in slicing through towers 1 and 2, thereby placing the towers in jeopardy even without the fires.
The prices for Imron paint jobs have everything to do with the labor-intensive nature of the preparation and paint process, and with the toxicity of the isocyanate cross-linkers used (requiring PPE for the paint shop workers). Preparation for powder coating is a lot less of an involved process - you need racks, an applicator gun, the powder itself and a suitable large oven & that's it. No solvent handling/recovery, no problems with overspray, few toxic effects (unless you breathe it in directly). The powder itself doesn't require clean-room conditions in order to adhere properly.
Steel didn't melt at WTC 1, WTC 2 or WTC7 for that matter. It didn't have to melt. Because it softened instead, losing over fifty per cent of its original strength in the process. Thermal expansion was also a factor, resulting in the sagging of the affected floors (ex. WTC 1&2) and the loss of the anchorage for the horizontal column support members (particularly in the case of WTC7). Fire protection coatings weren't up to modern standards, which did not help - nor did the presence of copious amounts of papers, files, furniture, rugs, and other combustibles (particularly in WTC7, which burned viciously for hours). It also must be remembered that the jet liners punched through a number of support members in slicing through towers 1 and 2, thereby placing the towers in jeopardy even without the fires.
Last edited by kunsunoke; 12-12-13 at 10:38 AM.
12-12-13, 10:55 PM
#34
Senior Member
The suggested processes for 531 at least does not require post joining heat treatment. It was used elsewhere and did have some other processing notes for the specific use/application. Penton used 531 for some motorcycle frames, and it was also used in some airframe sub assemblies such as engine brackets. You can even stick weld the stuff.
Not all powdercoat requires 400° F to transform.
12-12-13, 11:23 PM
#35
The Brutally Handsome
I've only had one frame powder coated but I was not pleased with the results. It came out with a wavy texture that looked terrible in the light. And as other have mentioned, it seemed really thick, covering some of the frame's finer details. I was more happy with the rusty scratches it had before!
12-13-13, 12:49 AM
#36
Other Worldly Member
Yum, more zombie frames. I'd walk back to that LBS with a D cell and a couple of leads and restart that frame "Clear!".
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