Head Covers- Black Anodized?

[SoullesS]

Here's the low down, I've got an opportunity to get some parts black anodized and I have a few in mind but I'm not entirely sure they are all possible. (by the way, my bike is an 01 V11 Sport)

 

I'd love to do something with my head covers, I've searched the forum and there were several topics describing powder coating which from what I understand can be done with any material. Black anodizing, however, is specific to aluminum I believe so I guess my question is whether the head covers are pure aluminum or something mixed or if anyone has done this before and can comment on the results. I know they are coated with that greyish paint which I will need to strip off (I suppose I would use a sand blaster) before the process can be done but I don't want to proceed if it won't work.

 

My second idea involved the exhaust cans which from what I can recall have an aluminum sheath that covers the actual can. Same thing, I wonder if anyone has had any experience with this.

 

I was told by the contractor that the process takes place at 72 degrees so there should be no risk of warping and that the finish shouldn't dull in any way due to the heat.

 

I realize there are benefits to the powder coating and that it is tried and true, however, free is free and I'm interested in the result.

 

Thanks for any help!

[Skeeve]

I believe the Guzzi valve covers are aluminum castings.

 

Typically, anodizing only works on wrought aluminum [particular Al alloys] & cast aluminum has too much magnesium or copper or zinc in it to allow for anodizing.

 

In short, you may be out of luck, but don't quote me on that. You'll need to do some further investigation.

 

Keep the rest of us informed w/ whatever you find out...

[Tom M]

I'm no expert but I have a (very) little experience with this so here's my take:

The rocker covers are definitely die castings, they look to me like an aluminum alloy (I think so but not 100% sure), so I believe they are OK to anodize. There's a slight chance that they're a zinc alloy though, so you may want to ask your vendor if he can test one. Some aluminum alloys have zinc in them but it's not a high enough percentage to preclude anodizing. OTOH alloys that are primarily zinc cannot be anodized and may be damaged in the anodizing bath.

 

Skeeve, I could be wrong here but certain aluminum alloys may not be good candidates for hard coat anodizing but are OK for standard anodizing.

 

I just looked at the stock black cans that came with my bike and they appear to be anodized. The guzzi black cans are known to turn purple-ish after a while so maybe anodizing is not the best option for them? Could be the supplier just did a poor job but your vendor could do better

 

I know there's a metallurgist on this board (Mattress?), maybe he will weigh in with something more definitive...

[slowkitty]

Had mine powdercoated black ... not bad, no flaking. Just make sure that the covers are completely stripped and cleaned before powdercoating.

 

Cheers

 

Cat

[stobie]

I've been in the anodizing biz for 18 years, and can anodize any of my stuff for free. I would pay somebody to powder coat my valve covers.

 

All castings anodize poorly; die castings are awful.

 

 

Edit-in: Never bead- or sand-blast anything you want to have anodized. The blasting media tend to embed into the aluminum, and some of the stuff you are trying to clean off gets hammered into the surface as well.

[Ryland3210]

I've been in the anodizing biz for 18 years, and can anodize any of my stuff for free. I would pay somebody to powder coat my valve covers.

 

All castings anodize poorly; die castings are awful.

Edit-in: Never bead- or sand-blast anything you want to have anodized. The blasting media tend to embed into the aluminum, and some of the stuff you are trying to clean off gets hammered into the surface as well.

 

Very interesting.

 

I have had 6061-T6 sheet metal "clear" anodized and machined aluminum bar stock anodized blue and gold successfully. But, can 6061-T6 and heat treated 356 alloy be anodized to a matching appearance? What about clear? Which colors can be used to make both metal alloys match in appearance. What if the metal had been glass beaded before anodizing?

 

Thanks in advance!

[stobie]

Very interesting.

 

I have had 6061-T6 sheet metal "clear" anodized and machined aluminum bar stock anodized blue and gold successfully. But, can 6061-T6 and heat treated 356 alloy be anodized to a matching appearance? What about clear? Which colors can be used to make both metal alloys match in appearance. What if the metal had been glass beaded before anodizing?

 

Thanks in advance!

 

We have found that 6061 and 356 behave very similarly in the process, and can actually be processed together. As far as making them match, I haven't tried; but black would be the best bet for matching any alloys. If you were trying to match a casting to a wrought alloy, 6061 and 356 give you the best chance.

 

I would avoid glass bead blasting in any case. If you are bent on having a bead-blasted finish, try to find someone doing ceramic bead blasting. Ceramic beads tend to delaminate like an onion instead of shattering, and therefore don't embed.

[Guest Mattress]

356 is probably the only alloy I can think of that you might find on an engine that could be a candidate for annodizing. It is basically Aluminium, Silicon, and a pinch of Magnesium low enough to be ok for process.

 

Beware, that does not address anything about casting quality. If its a chinese swiss cheese job (surfaces are not good indication of internal quality) I would be afraid of poor results.

 

Previous poster is very wise. Die castings are almost always made from secondary alloys (remelted scrap) and contain a lot of junk, especially Iron and zinc has a high allowance too. That combined with typically high copper content means a fantastic experiment in galvanic cell corrosion.

 

Annodizing is a corrosion process essentially. Wrought alloys (not all types) typically do not have such high levels of sensitize elements and they are made much purer and the microstructure is nice and refined. They are good candidates.

 

Well thats a short Metallurgy lesson.

 

Honestly, I think you're on a wrong and expensive path. If you want colour matching cans and covers I'd go with something else, like Jet coating. They have a coating that is pretty damn close to looking like polished stainless. Was a plan of mine to make all exhaust look like my staintunes.

 

Also, if you just want colored covers call MPH. Guzzi has a range of color codes to choose from. I just chose to replace my crash damaged valve cover instead of repair and repaint. Less than a hundo bones I recall.

 

P.S. zinc die castings aren't used as much as they used to be. The aluminium die casting process got refined enough to be more competitive through the 80s. And the Al castings are stronger and lighter. Still zinc die castings are used a lot for small parts like the inside of Schlage locks because it flows great and meets the strength needs if not made in china. Anyone here recently build a house and have a rash of breaking locks?

[Ryland3210]

356 is probably the only alloy I can think of that you might find on an engine that could be a candidate for annodizing. It is basically Aluminium, Silicon, and a pinch of Magnesium low enough to be ok for process.

 

Beware, that does not address anything about casting quality. If its a chinese swiss cheese job (surfaces are not good indication of internal quality) I would be afraid of poor results.

 

Previous poster is very wise. Die castings are almost always made from secondary alloys (remelted scrap) and contain a lot of junk, especially Iron and zinc has a high allowance too. That combined with typically high copper content means a fantastic experiment in galvanic cell corrosion.

 

Annodizing is a corrosion process essentially. Wrought alloys (not all types) typically do not have such high levels of sensitize elements and they are made much purer and the microstructure is nice and refined. They are good candidates.

 

Well thats a short Metallurgy lesson.

 

Honestly, I think you're on a wrong and expensive path. If you want colour matching cans and covers I'd go with something else, like Jet coating. They have a coating that is pretty damn close to looking like polished stainless. Was a plan of mine to make all exhaust look like my staintunes.

 

Also, if you just want colored covers call MPH. Guzzi has a range of color codes to choose from. I just chose to replace my crash damaged valve cover instead of repair and repaint. Less than a hundo bones I recall.

 

P.S. zinc die castings aren't used as much as they used to be. The aluminium die casting process got refined enough to be more competitive through the 80s. And the Al castings are stronger and lighter. Still zinc die castings are used a lot for small parts like the inside of Schlage locks because it flows great and meets the strength needs if not made in china. Anyone here recently build a house and have a rash of breaking locks?

 

ZA27 is a high strength die cast alloy, but cannot be used in the hot chamber process. Zinc is deliberately alloyed with aluminum in die cast alloys. It is not considered a contaminent. In many applications, such as side view mirror brackets, conventional zinc alloy was preferred over aluminum for the combination of strength and thinner walls to keep the weight down. For thinner walls, fine detail, high volumes, and where strength is required, zinc die casting often is chosen. My guess is you know all this. I haven't had any locks break lately except due to flimsy steel stampings. I frequently see plastic parts break which I wish were zinc instead.

[SoullesS]

Thanks for all the helpful advice. I've decided to proceed with black anodizing the aluminum sheath from the exhaust cans while abstaining from the valve covers for the very clear reasons discussed. When they are returned to me I will be glad to post some pictures for anyone interested.

 

At this point I may be stretching for possibilities, but since this topic seems to have the attention of some very knowledgeable persons I would like to inquire about plating, in particular copper plating. I've done some very rudimentary google/wiki researching and have some idea as to the process involved however I'm having trouble finding info about some of the specifics. It seems that any metal that can conduct a current can be plated and as a result there is an increase in the thickness of the material. What I'm most concerned about however is the temperature and whether there is any precedence of this process being used under similar conditions. I've seem Triumph valve covers with what appears to be copper plating but I haven't had the opportunity to ask if it was the real deal or some sort of powdercoating sham. I plan to call around to some local places in the next day or two but I thought I would throw the idea out to you guys since you've already helped me out so much already.

 

Thanks again,

~Kyle

[GuzziMoto]

I'm not the expert on this that the others are, but copper plating it the base coat for chrome plating. The problem would be corrosion without some sort of protective coating. You can also copper leaf parts as long as they don't get to hot and again you protect them from corrosion with a top coat.

[Ryland3210]

I'm not the expert on this that the others are, but copper plating it the base coat for chrome plating. The problem would be corrosion without some sort of protective coating. You can also copper leaf parts as long as they don't get to hot and again you protect them from corrosion with a top coat.

 

Aluminum is chrome plated by first plating it with copper, then nickel, then chrome. The aluminum is not polished to a mirror finish. It is deliberately left with a matte finish which gives the copper a bettter bond. The copper is then mirror polished prior to the nickel and chrome platiing sequence.

 

Heat is no problem as long when the plating is done well. The aluminum has the lowest melting point. Corrosion resistance is good.

[Ryland3210]

Thanks for all the helpful advice. I've decided to proceed with black anodizing the aluminum sheath from the exhaust cans while abstaining from the valve covers for the very clear reasons discussed. When they are returned to me I will be glad to post some pictures for anyone interested.

 

At this point I may be stretching for possibilities, but since this topic seems to have the attention of some very knowledgeable persons I would like to inquire about plating, in particular copper plating. I've done some very rudimentary google/wiki researching and have some idea as to the process involved however I'm having trouble finding info about some of the specifics. It seems that any metal that can conduct a current can be plated and as a result there is an increase in the thickness of the material. What I'm most concerned about however is the temperature and whether there is any precedence of this process being used under similar conditions. I've seem Triumph valve covers with what appears to be copper plating but I haven't had the opportunity to ask if it was the real deal or some sort of powdercoating sham. I plan to call around to some local places in the next day or two but I thought I would throw the idea out to you guys since you've already helped me out so much already.

 

Thanks again,

~Kyle

 

The die cast valve covers can be anodized black or other colors. Hi quality die castings have a porosity-free skin on the surface. If quality is not very good, there may be "flow lines" where two leading edges of the molten aluminum come together without welding together or other surface defects. These are usually impossible to buff or polish out completely. I would classify the valve covers on my bike as high quality. They are very easy castings to make, whereas the Centauro shift lever castings I have seen are more difficult to make and were of poor quality. They had been sand-blasted, a remedial method commonly used in an attempt to make such defects less obvious.

 

Anodizing is a process whereby the aluminum is the anode, the opposite of plating when it is the cathode. In the process the aluminum on the surface is oxidized in a solution that includes a die to generate the desired color. Black is the most consistent and easiest (except for clear). There is no negative effect on the temperature limit of the original aluminum. Die cast aluminum alloy generally melts at around 1150 F depending on the alloy.

 

Powder coating I am familiar with on diecast parts for automotive sideview mirrors, for example, is baked at 350 degrees F to fuse the coating onto the surface near the coating's melting temperature. Therefore, temperatures approaching that level could cause the coating to melt.

 

If you decide to go with copper plating, they will quickly lose their shine, unless they are clear-coated. For room temperature applications, it is common practice to clear coat brass bathroom fixtures, for example, which can get up to 160 or 180 F on the hot water side. I am not aware of a clear coating that can withstand 350 degrees, and I do not have expertise in this area.

[GuzziMoto]

There are hi temp powder coatings available. And while copper plating will withstand hi heat, it will discolor. And copper leaf cannot withstand hi heat at all due to the sizings inability to take the heat. As for anodizings ability to take the heat, that depends on the chemical(s) used to dye the layer of corrosion. Most take heat well, some do not.

[Ryland3210]

There are hi temp powder coatings available. And while copper plating will withstand hi heat, it will discolor. And copper leaf cannot withstand hi heat at all due to the sizings inability to take the heat. As for anodizings ability to take the heat, that depends on the chemical(s) used to dye the layer of corrosion. Most take heat well, some do not.

 

Interesting. I'm not familiar with the term "sizings" in this application, and would also like to know how more about high temperature powder coatings. How high, and what color limitations, if any?

 

Also, I would like to know which dyes used in anodizing are sensitive to heat.