Vacuum Metallization???

[drfjr1976]

I was looking through my "powder Coating" magazine and saw that they had a short ad on how appliying a bright metallic layer by vacuum metallization, than applying a clear powder is being used to replace chrome plating in some selected markets. Does anyone know what is vacuum metallization? Just curious, because it looks pretty close to the real thing, Chrome.

[non-stick]

Vaccum matalization has been around for years. It's not really a new process,truth be known. Back in the days when computers were first made, this process was incorporated to "shield" electronic componantry.

Basically what happens is this.....
A protective "cup" if you will is formed around a plastic mold to make a case for printed circuit boards and save them from electromagnetic interferance (EMI) from surrounding structures. Think of it this way... you have a REALLY old car and you hear this constant "buzz" from the ignition coil and wires controlling spark through your AM radio all the time when you accelerate. What you do is get a noise supression wire to help cut down on that effect therefore, creating your own EMI resistor. Vacuum metalization enclosures are no different. You take a sensative piece of electronic equipment and enclose it so that it doesn't have any interferance from a surrounding electronic structure. Say maybe such as a vacuum tube (like in the olden days) or a microprocessor (like those used in your very own television set). No doubt you have seen these such vacuum formed metals before but just didn't know what they are.

Now... with that said, the reason that you see them being clear powder coated is for insulation properties,no doubt. If the metal form has not been completed yet by means of installing the printed circuit board (PCB) yet.... it will withstand the heat of the application. Of course... if the PCB is in need of the EMI resistance... there are many companies out there that make a wet-spray application for this function as well. I've used a humiseal product with great success over the years as well as parylene deposition with the same if not better effect. All in all.... it's just a coating that insulates, comprised of a polymer structure. Liquid, monomer deposition, electrostatic powder coating... it all reaches the same result in the end. A metal box that houses electronic equipment coated with a non-conductive coating. Another good example is a turn signal relay found in pre-mid 80's automobiles. Nowadays they make them out of plastic.... but if you go to the junkyard, you'll see them. Funny little metal squares that plug into a block or cluster of some sort. THOSE are also vacuum formed metals or a derivative of it (stamped castings).

The process is this : A mold or "negative" is made of the part you want to surround. Resin capable of withstanding heat and pressure is made from that mold creating a "positive" of the original structure. It is then placed in a chamber and thin metal is sucked over the top of it. The vacuumed metal now leaves another negative of the cast and is removed and trimmed of any excess. THIS is your vacuum formed metal. You have a choice of either coating it now ( the ad in which sparked this post) or putting your PCB in the metal and leaving it be or coating it later if you wish. Hope that explains the process and what it is exactly..... Russ

[non-stick]

oops... I almost forgot about another process in which this takes place. A molded piece of thermoset plastic is laid in the same type of chamber and a very thin (and I mean extremely) sheet of aluminum is then vacuum formed around the piece to either replicate "chrome" or provide a conductive surface. (this is probably what you were originally looking for answer wise). It's most commonly found on older cars also. The reflective surface of the inside of your headlight (the newer ones where you replace the bulb, not the whole headlight like an older automobile) is a good example. It doesn't hold up to weather all that well. Just look at any old car that's been around and check out the trim or shiny work on the front and you'll notice all the flaking of the material. The ad that sparked your query is more than likely dealing with that. It can be powder coated because :

1) it is now a conductive surface
2) it's a metal overlay on top of a thermoset plastic capable of withstanding heat (it's already cured and therefore will not melt again)

I'd also be willing to take a wild guess that you can anodize,gold plate or do most anything to these vacuum formed metals much like you would any other piece of aluminum making it a popular choice for being a cost effective way to have a "fake chrome" surface. The clear coat is no doubt a protector in this example against the harsh elements making it last longer. Hope that helps..... Russ

[non-stick]

here, this link should help explain what I just said a little better.

http://www.ce-mag.com/archive/02/09/arnold.html

Make note of the bottom graph where they did a test comparison against vacuum formaed metalization and a "silver paint" and basically had the same effect. The keen eye will notice that "silver paint" is VERY much like the Silvaspray we have here on the Caswell site. Things that make ya go hmmmmm, eh? Maybe that will spark a few ideas for some of you. Vacuum formed metalization ( very costly machines and processes) or Silvaspray ( extremely cost effective and available to the hobbyist at this very site). Kinda makes you wanna investigate where they use this process and go after a little of this business now,huh? lol. The charts don't lie, folks..... tests have shown that for quite a few purposes, they are one in the same in a few cases. Think of the possibilities you can offer yourself as a hobbyist, if not your customers (if you are at that level). Hey... I have this plastic trim.... can you refinish it? Can you refinish it and powder coat a clear on it? Can you not only powder coat a clear on it, but put one on with a candy tint or metallic flake?? The answer is yes. Of course... my question for you all now is..... did I spark any new business ideas for any of you,hummmm? lol. As always, I hope this helped somebody out there..... Russ

[drfjr1976]

The ad was about where they are useing as a replacment for chrome plating rims and such. So could this Silvaspray be used on rims to replicate chrome. Say apply a powder primer, than the Silvaspray and than finally applying a powder clear over that for protection?

[non-stick]

I've personally never used Silvaspray myself. I'm thinking that might be a question for Caswell to answer. Be kinda neat if we found a new use for the stuff though,huh? I'm thinking it may be a possibility. Don't see why not. The chemical make-up of it looks to be about right. Kinda neat hashing this out like this... seeing this is what the boards are meant for. Educate each other and come up with new ideas to utilize Caswell products ina more purposefull manner. Lemme know if you decide to get some Silvaspray, I have a car grille that needs doing ...... Russ

Hey Caswell..... any input on this subject?

[drfjr1976]

I haven't been able to find any pictures of items done in the silvaspray. I have found a dash done in the silvachrome, but none of the spray. The silvachrome might even be an option but it looks to be much more complicated than the silvaspray and more expensive.

[mcaswell]

Silvaspray is a thin layer of silver, topcoated with lacquer. It's not really durable, and it's not suitable for high heat applications. It's one of several options to make non-metallic parts look like chrome.

Silvaspray isn't meant to be a final coat. It strictly makes non-metallic parts conductive, so they can be plated. We haven't tried powder coating over Silvaspray.

[non-stick]

grrrrrr..... looks like it's back to the drawing board for us then, guys. Here I thought we had sumthin to corner the "chrome" market with and take the world by storm,lol. I still stand by my original statement as it being good for computerized electronics and being a good conductive coating though. Give it time, folks..... all's it takes is us putting our heads together collectively and finding the right path to go on.... Russ

[drfjr1976]

Can silvachrome be coated with a clear powder or does it have to be topcoated with lacquer? could it handle say 330 for 20 minutes? I know you said it is not sutible for high heat, but could it handle it for the short period?