[mcrado]

Okay friends, I have a four part question.

I have a number, in the thousands, of aluminum cans. I am cutting a portion of out of each can, and then eventually hoping to take to a local anodizing plant to have anodized. Here's what I need in order to do that:

One, how do I take the lacquer coating off the outside of the can. From what I've read online, each can is printed and then coated with a clear protective varnish, which must be removed entirely before the anodizing process. My contact at the plant told me that the sulfuric bath during the anodizing is not strong enough to take this off. Through my research, the possibilities I could come up with are aircraft paint remover, Behr's the Stripper, or a homemade solution made of baking soda and water. All of these options were for other types of applications, hence why I am reaching out in hopes somebody has any idea.

Two, I need to remove the four-color printed image that is rolled onto the cans before the outer varnish is applied. The most obvious solution I could come up with is sandpaper, but the problem with this is, as with cleaning aluminum pots and pans, any sandpaper or steelwool will scratch the surface and a fine finish will not be attained. The ultimate goal would be to have these aluminum pieces shine like colored chrome. So is sandpaper out? Any other possibilities? Will the varnish remover do this process as well?

Three, I need to remove the inside coating. I have a feeling that this will be the most difficult. The coating, from what I have picked up online, is vinylite. I have read that vinylite is dissolvable in acetone or toluene, but I think this is more in a science-class from powder form. I also have read that you can use the previously mentioned aircraft remover, which I heard was not-good stuff. What are some safety precautions? I know that the coating is pretty light, so I can't imagine this would be a labor intensive process for each individual can, but obviously doing thousands of them is time-consuming.

Four, I need to prep and clean the aluminum sheet for anodizing. File down the sharp edges with a metal file? Emory powder and a wash? Alcohol? Any suggestions?

Like I said, I need these things to be pristine in the end result, like little mirrors hopefully.

Thank you in advance for any help you all can give.

Michael

[RomanLini]

This might not be the solution you wanted; but maybe you could contact the can manufacturer, and order "thousands" of unpainted unvarnished cans?

Since they can drinks for small drink companies they may be willing to deal with smallish quanities like yours, and selling unfinished cans might be an easy sale for them. Just guessing of course, but worth a couple of phone calls.

[mcrado]

I very much appreciate the input, and you are clearly trying to be helpful. Unfortunately the project is centered around the fact that I am using recycled cans. And if I were going to buy aluminum, I would buy sheet aluminum and avoid having to cut up a 400# of cans. This input could help me in the future though, and I will keep it in mind.

That being said, they need to be recycled, I want them to be used soda/beer cans, and I must truly find a way to fulfill the original goal.

Thanks again,
Michael

[RICHARD ZASTROW]

How about heating the cans high enough to burn the paint/varnish and leave the can in usable condition? I don't know what that temp. would be, but I know some recycling companies burn the paint off prior to melting the scrap aluminum cans.

Dick Z

[fizzissist]

Your answer lies in post #2.

You're thinking your "free" cans are a financial plus for the basis of your project, and from your outline, you're going to spend more time and money screwing with these "free" cans than if you bought pre-fab blanks, or the raw material and started from there.

The bulk production of aluminum cans is a stunning sight. Quite literally, the number of cans you want represents the output of a few minutes from one of the major suppliers.

If what you want to end up with doesn't require the can configuration, then it may be cheaper to simply have the parts made from scratch. What you're doing isn't hobby level. To approach it like that means you're willing to spend ungodly hours...and who knows what in chemicals and haz mat issues. I'm familiar with trying to remove those coatings. Itza *****.

On the bright side (pun intended), the mirror finish is easy with electropolishing.

[Cux350z]

400 cans is about 10 seconds worth of production on a fast line. The can suppliers do not provide them with top caps.

[Delw]

I very much appreciate the input, and you are clearly trying to be helpful. Unfortunately the project is centered around the fact that I am using recycled cans. And if I were going to buy aluminum, I would buy sheet aluminum and avoid having to cut up a 400# of cans. This input could help me in the future though, and I will keep it in mind.

That being said, they need to be recycled, I want them to be used soda/beer cans, and I must truly find a way to fulfill the original goal.

Thanks again,
Michael

Find a can company that makes cans out of recycled alum and your golden

[fizzissist]

400 cans is about 10 seconds worth of production on a fast line. The can suppliers do not provide them with top caps.

Haven't seen this one, just read about it years and years ago..output was 3600 cans/minute. I know one major brewery in So. Cal had it's own can plant around the corner from the bottling plant. They shuttled the cans by truck.

...back to the instant issue.... At what point does putting more resources into a "recycled" product make it better than simply using a new product?

[S3MIH3MI]

Try Caswell they have both the knowledge and the product you will need. The guys in the forum are very knowledgeable and will be able to point you in the right direction. They have a stripper for powder coating that may work very well. I use poly stripper but it is a gel and you may find it easier with a dunk tank type of stripper.
Good luck

Plating Kits Electroplating Kits Aluminum Anodizing Kits Powder Coating Systems Metal Polishing And Buffing Supplies - Caswell Inc.

[bwprice100]

.
Hi Michael

Could I suggest vibratory or tumble cleaning, which also do the de-burring for you. Perhaps you could use a recycled media

With a bit of research and experimentation you may come up with something.

I know of people who have used those small electric cement mixers with good affect.

Brian

[mcrado]

Okay, I will try to answer everyone in this post, so please be patient.

400 cans is about 10 seconds worth of production on a fast line. The can suppliers do not provide them with top caps.

I actually said 400# of cans, as in pounds, which is roughly 10500 cans, which to your point, is still only 5 minutes on a production line, or as fizzissist claims at 3600/min, only ~3 minutes. At any rate, how fast a production line can produce cans is absolutely meaningless to me; what is meaningful is the collection and transformation of 10,000 cans that have been trashed, for my purposes, and not the use of post-recycled aluminum cans. I appreciate the input though.

As for your point, fizzissist:

At what point does putting more resources into a "recycled" product make it better than simply using a new product?

There are two primary assumptions that your are mistakenly making: 1. That the fundamentals of this project I am undertaking has anything to do with 'better' or 'worse,' though God knows who you are to define those without knowing the purposes of the project and 2. That putting resources into this project is a down-side, and not the point.

The intention to use recycled cans is directly related to the purpose of the project; there is no better or worse. Your confusion is rooted in the fact that you think I am producing some sort of a product out of recycled goods, and that I am doing so out of some moralistic, or money-saving desire; these are poor, but valid and common assumptions. The use of recycled cans, directly from the consumer/user, is inextricable from the purpose of the project; it is the only solution. Again, there is no 'better' or 'worse'. I hope this makes my intentions, although I am admittedly being cryptic, a little clearer.

Furthermore, the fact that I am not using a new product and putting 'more resources' into a recycled product is again, interrelated to the project itself; the work is a self-imposed requirement, and the work to end-product relationship is the pivotal part of the project. The foundation, if you will.

To continue to respond to you fizzissist, you are for some reason emphasizing "free" and a "financial plus," as if I said either of these things. You also said, "You're thinking," which I have no idea where you got this from, unless you can read my mind? I never mentioned either of these things. In fact, like you have pointed out, I will spend more money and time to do use recycled cans. EXACTLY. I am purchasing these cans, 10,000 of them, from a local recycling plant. And I will, at the end of a year+ with the help of collaborators, have put an immense amount of work into the project. Which brings me to your third assumption, that this project is centered around financial and production-based efficiency, when in fact, it is entirely the opposite. This specific project is within a budget, and within that budget is allowance for the allotted money for the cans, and also the immense amount of work that will be put into it, once again, the foundation of the project. The work to end-product relationship.

Please, in the future avoid assuming what the end-result of the project will be, and like a couple other more helpful posters, if you are willing, please help me find a solution for the exact problem at hand: my original request, not what you think my request is.

Hi Michael

Could I suggest vibratory or tumble cleaning, which also do the de-burring for you. Perhaps you could use a recycled media

With a bit of research and experimentation you may come up with something.

I know of people who have used those small electric cement mixers with good affect.

Brian

Thank you Brian; do you think that this process will remove the inner and outer coatings? The printed image as well? If so, what sort of companies would I inquire to about the process?


S3MIH3MI, I will contact them and see what I can come up with. Thank you!

Delw, I will keep your comment in mind. Thank you!

[mcrado]

Also, I apologize in advance if any of my last post comes off as rude or disrespectful, I simply want to make it clear that the 'Why' is very much concrete, and now I need the 'How.' I fully understand the implications of the project, and emphasize that this is not a 'Hobby,' though I am obviously not necessarily familiar with stripping in particular thousands of aluminum cans. At any rate, it will be done, the question is how. Arguing the why when it is uncompromising is cumbersome and useless.

Thanks,
Michael

[bwprice100]

Thank you Brian; do you think that this process will remove the inner and outer coatings? The printed image as well? If so, what sort of companies would I inquire to about the process?


S3MIH3MI, I will contact them and see what I can come up with. Thank you!

Delw, I will keep your comment in mind. Thank you!

Not an expert on this, I was an expert in making cans though the only reason I am aware of this subject is that I am researching it my self for polishing stainless parts.
If you Google tumble deburring you should find plenty of stuff with regard to machines and the media available.
With regard to it working, I am not sure but it would be worth talking to an expert and I am sure an easy experiment could be set up.

My main hobby is classic motorcycles and a regular thing that comes up in my circles is how to clean the insinde of a petrol tank. If you Google tumble cleaning a petrol tank you will see some very ingenious set-ups

I hope this is of some help Brian

[stinkpie]

I think fiz raised a valid question. Whether one likes to believe it or not, economic efficiency is really at the heart of whether or not a business or idea is feasible. Economically unsustainable industries or ideas should only be supported if they have some important or global/national interests where the government(s) will give subsidies to those naturally uneconomical industries in order to keep it afloat artificially, e.g. important defence industries, space programs, or something.

Otherwise, economically unsustainable industries/businesses or concepts are often doomed to fail, if not at the microeconomic level of the firm, then certainly at the macroeconomic level for the national economy in terms of efficient use of resources.

For example, a toothbrush manufacturer in the commodities market of toothbrushes will not necessarily want to invest into raw material production (e.g. polymer processing) but instead may opt to purchase thermoplastic polymer pellets from major polymer suppliers and focus on the mass production of the goods itself. The same idea for why that same toothbrush manufacturer should not be worried about producing their own energy, building their own factory buildings, the raw building blocks used in said building, manufacturing equipment, computers, electronics, software, operating systems, word processor, light bulbs, pencils, etc - in order to keep the company operating. They will simply buy those items because other companies make them better, more efficiently, more effectively and more economical to make them cheaper. It is more efficient as a whole.

This goes back to this topic for the use of recycled aluminium cans and to Fiz's point. Often times the national or global infrastructure operating at a larger scale with the right technologies and equipment and logistical infrastructure is often more efficient at the recycling as well as even eventually to the re-production of new blank cans, than for any manufacturer will be to create new uses for old cans via some kind of processing. I guess his question is basically asking, whatever it is that you are trying to do, how does that fit into the bigger picture of the world?

Another analogy is that, it is perhaps arguably more efficient and 'green' for a powerplant to be producing all the electricity and then providing the energy via the grid then used to power the future electric vehicles, than it is to have each individual car produce the energy itself and have it retrofitted or engineered to the energy efficient and 'green' state that it needs to be. Simply put, focusing all the energy production at major providers such as a power plant, is more efficient and also often more green than it is having every new electric vehicle designed to have energy production capabilities on every vehicle and then pumping in the energy source in for processing at the car level like what we are kind of doing now (e.g. pumping gas into every car, as opposed to having gas converted to energy at a power plant where it is more efficient and often more environmentally friendly).

My first guess is that maybe this is for some kind of 'green' initiative. Say for proof-of-concept for some proposed 'green' processing technology that you may want for patent applications. It is also possible it is an 'artistic' project, say you are building an art piece that wants to maintain true to its artistic message of using 'used' but 'reprocessed' cans. Then ok, you may get a pass on the economics argument. Otherwise, if this is for any kind of 'green' initiative, you should have a good answer to Fiz about why you think recycling used cans by yourself and using your process can eventually beat out national or global infrastructure for aluminum recollection, recycling and reprocessing in terms of bigger picture economics. It all comes down to the bottom line. Right now, it is simply cheaper to do it the way it is currently done, which is collect a bunch of cans, crush them, melt and process them, then re-fabricate new cans. All with economies of scale and the necessary logistical infrastructure to make it happen cheap. Keeping in mind of course that quality controls often require cans to be in pristine physical conditions for use. It will still likely beat out any kind of 'home brew' recycling 'green' initiative you may have in mind in terms of say proposing that people reuse old cans instead of go through the normal cycle of remelt/reprocess and re-fab of new cans for use in the food/beverage industry again. If that is what you are doing, there are more problems you will introduce or have to find a solution to, e.g. fixing dents or deformations of used cans etc, which requires more resources, hence why large scale recycling and refabbing of new cans seem more feasible given the economies of scale.

If this is for an art project, or an attempt at proof-of-concept for say a patent application where ineffective use of resources is acceptable, then skip this. But the question is, what is your ultimate goal? After you have defined this, what is the cheapest and best painless way to get there? You want aluminium of a certain shape (perhaps not too different than that which can be derived from commercial aluminum cans) to be anodized. Now you got yourself a bunch of cans. The comment is that perhaps there should be proper planning before the execution. But the bigger question is what to do with existing cans? Well you can either throw heavier resources to do what needs to be done to the purchased used cans, and then to get to where you ultimately need it to be. Or, is it cheaper to cut your losses now, and go the other route and buy new can blanks, and then say resell the used cans back taking a hit on the loss. Which is cheaper ultimately? Again, if this is art or some kind of proof-of-concept, you are allowed a degree of economic inefficiency. Otherwise, it doesnt make sense to most logical thinkers to go the more expensive and painful route.

[dsage]

Perhaps I can make you aware of another gotch-ya. You stated early on that you wanted the finished aluminum to be mirror-like. I have considerable experience with anodizing and I can tell you that the aluminum will need to be "mirror-like" BEFORE you anodize it. Anodizing won't cover anything. Garbage finish in - Garbage finish out!
So you will therefore need to polish the aluminum before you submit it for anodizing.
Having said that, this may be the way you remove the coating. Cut the shapes from the aluminum can, (probably flatten them out) and then polish the coating off of them with a buffing wheel and abrasive. Carefully holding the razor sharp aluminum pieces of course.
Also be aware that anything left on the aluminum will inhibit the anodized finish therefore you will probably need to de-grease them (more chemicals).
I'm also surprised any anodizing shop would offer to anodize a bunch of (sc)crap aluminum for fear of messing up their anodizing line chemistry. Anything for a buck I guess.

Good luck !! Let us know how you make out.

Sage

[Fastest1]

Will the cans have either end still attached? Or will there be just a cylinder you need clean inside and out?

[mcrado]

Hey, so we're actually really getting somewhere, and thanks for that.

Uh, stinkpie:

I can't believe you made me read all of that after everything I wrote! But I guess you get what you give! This is not a business, in the traditional sense of the word, I am not making a product (as I said), and this has next-to-nothing to do with recycling or going 'green,' and of course I fully understand that the current recycling industry would be more efficient than some 'small time' recycle plant (though I don't think your overall argument is very strong, and this shared philosophy is possibly contributing to the 'someone else will do it' and 'well I can't do anything about it' kind of apathetic mentality that is rampant). At any rate, you hit the nail on the head in your last paragraph, so this discussion has nothing to do with my 'ultimate goals' which trust me, I fully comprehend. So per your instruction, I'll skip it. Thanks for the input though, some great reading, seriously.

dsage:

I didn't assume the anodizing would cover any blemishes, and I'm sorry for my vague choice of words. When I said mirror-like, I meant reflective, not necessarily without scratches or imperfections. I will do some minimal sanding of the edges to remove burrs, and perhaps some light polishing. Regardless, I don't think light scratches will detract from the finished piece and may even contribute to the intended feel. To sand off the paint would change the exterior into a matte finish, and would also take off some material of the already-thin sheet.

I will consider the buffing and polishing though, but again, this will probably make the pieces even thinner. And also, the pieces aren't really razor sharp, and as I said, I'm sanding the edges relatively smooth. Still, valid safety concerns for flying burrs, etc.

Thanks for the de-grease tip, will keep this in mind.

I have spoken with a local anodizing shop, and am going to test run 100 pieces. They told me that I needed to remove the lacquer and paint, which is what brings us to my first post.

Thanks for help!

Fastest1:

No, they do not have either end attached. They are ~3x6" rectangle, flatted (still working on the flattening part). Does this help?

--

Currently I am going to try the aircraft paint remover or nitromors route; though I am weary of disposing of large quantities of diluted chemicals. This seems to be like the only feasible direction for the quantity.

Related post: How can I remove the paint from a soda can? - Zoklet.net

Thanks all,
Michael

[u8w]

Michael,
I sent and email to you... I think....?
Curious what means you were able to accomplish your gaol? Thanks Kenny

[beone]

Get several 5 gallon buckets ,metal with lids. First one has paint stripper, make sure it's safe for al. That should take off most of the lacquer etc. next bucket is lacquer thinner or acetone or mek. Next bucket the same. Next the same. It may take several days in each bucket. But with enough buckets, always moving to a cleaner solution you should end up with a clean al product.
Dave

[mcrado]

Michael,
I sent and email to you... I think....?
Curious what means you were able to accomplish your gaol? Thanks Kenny

Hey Kenny,

So, I've made some progress, but I'm nowhere near where I want to be.

I tried sandblasting—worked all right, but very slow. I'm in Columbus, Ohio, and we have an organization called the Cultural Arts Center that has a metal foundry with some basic tools and a sand-blasting cabinet. The issue is that the pressure wasn't great—100 PSI at best, but after a few minutes it would drop down to maybe 20 PSI. It took me about 15 minutes to blast one piece, which for 1000 pieces, you can imagine why this wasn't a viable option. But, with the pressure dropping and the fact that the cabinet was loaded with play sand and not commercial blast medium, there could be some improvements to the process. Once I finished the one piece, which was already cut to the rectangle I wanted, I took it too a polish wheel with some abrasive and polished it down to a very nice finish in just a couple of minutes.

So after a little more research I came across the idea of soda blasting—this seemed like a better option because the commercial baking soda blast medium won't eat away at metal, only paint and lacquer. This worked beautifully—I used a portable blaster outside and blasted off the lacquer and vinyl backing from the pre-cut cans in about 3 minutes a can—much more likely. The finish ended up as a nice even matte—I decided I would finish 100 of them and anodize them and see how I liked the matte finish looked anodized before I did the full 1000.

The real issue with this is that without a dedicated blast cabinet, baking soda is just everywhere, which isn't really a problem for the environment, just needs to be hosed away. The issue is that for about 20 pieces I used an entire 50lbs bag. So again, this process is more efficient, but far higher costs for the baking soda. I decided I would do the first 100 still, without a cabinet, and if it worked I would invest in a dedicated blast cabinet—something that might be nice in my studio regardless. I say dedicated because I believe once you used a cabinet for soda or for sand, that's what you'll need to use forever—there may be a way to clean it, but I haven't looked into it enough.

One thing to note about both of these processes—because the undulating air pressure, and depending on how close the nozzle is to the aluminum, the blasting creates an uneven bumped surface that looks like it's actually stretching the aluminum in places. On the other hand, the process also flattens out the curled aluminum pieces to a certain degree, from the pressure. I'm sure there are metal presses or rollers that could flatten out the pieces completely, but again, haven't looked into this enough.

I will post when I get the first 100 finished, hopefully with pictures. I work on multiple projects at the same time, and with the hiccups (and the blasting outside during the winter last year) this one got pushed to the back burner.

I like the suggestion of beone, so I may try something like this. The issue again is how to dispose of the chemicals used for this, and have noxious chemicals in my studio (that I also do other projects in) for however long it takes to process ~1000 cans.

Let me know what you come up with, thanks for the input.

Michael