Forum etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.

Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.

Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.

Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.

"PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.

Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.

Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.

New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.

Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Five o'clock shadow

  • Filter
  • Time
  • Show
Clear All
new posts

    Five o'clock shadow

    So, here's an odd one. The unpainted metal casing for my Tandy 1000 RSX has always had a more distinct, "duller" finish than say, the comparable RL or RLXs. While looking over the system this evening, I noticed what appeared to be metallic dust on the inside of said casing. On (much) closer inspection, the metal has apparently sprouted a short shag of zinc whiskers. Awesome.

    Heretofore, my only experience with zinc whiskers has been in raised floor data-centers. I've never seen such a thing outside of work. Is this pretty common in the vintage-computer world, where everyone just wipes things down and goes on with life, or should other protective/preventative measures be taken?

    Are you sure that you're dealing with zinc whiskers? Perhaps you're looking at "white rust" ? But yeah, zinc whiskers do show up on zinc electroplate sheet metal. And they're hell on wheels for modern circuitry with small geometries. Probably not so much with your Tandy HX.

    I've read a few articles that formation can be retarded somewhat by heating the metal in question to relieve stresses, but that sounds a bit extreme in your case. I'd probably go over the surfaces with a good one-step auto paste wax. It's not going to stop those whiskers from growing, but it might contain them a bit.

    Short of stripping the galvanizing from your sheet metal and refinishing in, say, nickel, there's probably not much you can do as the cause appears to be physical and not chemical.

    It's sure lined some pockets of remediation services and sold a lot of replacement data center floors.


      Originally posted by Chuck(G) View Post
      they're hell on wheels for modern circuitry with small geometries. .
      Whiskers are a big issue for high reliability electronics. Typically no pure tin coatings are allowed.

      Here's a website dedicated to whiskers:

      Lots of nice hairy pictures.


        Tin whiskers are one thing and unrelated to the zinc whisker issue.

        Zinc whiskers seem to arise from electroplating steel where stresses haven't been adequately relieved. It can take many years for zinc whiskers to appear, if they appear at all. Currently, the only advice given is replacement of the offending elements. Evidently, painting doesn't do much--the micron-thick whiskers will apparently poke their way up through most coatings. They do not occur on hot-dip galvanized steel; only on electroplated steel. It seems that adding a bit of lead to the plating mix prevents them.

        There's been a bit of work done on ameliorating the situation. There's some evidence that heating the offending part slows the growth but doesn't prevent it. But currently, replacement is the only sure-fire solution.


          Originally posted by Chuck(G) View Post
          Are you sure that you're dealing with zinc whiskers?
          Mostly sure. When blown across, the whiskers shimmer like Christmas tinsel (without breaking). Pretty cool effect, despite the gravity of the situation.

          I noticed one other property that I hadn't quite expected, and must have missed in my own readings - the whiskers seem to be completely water soluble. My plan at this point is to remove the system mainboard and other components, wipe down the chassis, and give it a light, once-over with some steel wool. Heating it in the oven would be do-able as well, if I had any idea at what temperature or duration to leave it in there.


            Originally posted by Chuck(G) View Post
            Tin whiskers are one thing and unrelated to the zinc whisker issue.

            Zinc whiskers seem to arise from electroplating steel where stresses haven't been adequately relieved. ... They do not occur on hot-dip galvanized steel; only on electroplated steel. It seems that adding a bit of lead to the plating mix prevents them.
            Hmm. There's a video on the first page (about 3MB .mwv) in the link called "Zinc Whiskers on Hot Dip Galvanized (HDG) Steel and Whisker Bending Due to Electrostatic Attraction, J. Brusse, A. Purves"

            Most of the papers on zinc whiskers imply that tin and zinc whiskers have a similar mechanism. Anyway no one seems to understand the root cause.

            The tin whisker problem became more well known (to me at least) when everyone tried to go "lead-free". Some people tried to replace solder coating with pure tin plating. I recall seeing a PC board drawing with a revision history that started out solder coat, then changed to tin plate, then finally changed to gold flash.
            Last edited by xprt; November 26, 2012, 03:40 PM. Reason: typo


              Originally posted by Chuck(G) View Post
              There's been a bit of work done on ameliorating the situation.
              Having dismantled/cleaned/buffed the chassis, my work is done... for now. I did a pretty swell job, so I'm going rate this effort as a "10" on the Gil Amelio scale.

              We'll see how long it goes before needing another shave. I'll report back in a year or so...


                Originally posted by Cloudschatze View Post
                We'll see how long it goes before needing another shave. I'll report back in a year or so...
                They're baaack...


                  Yikes--did you try coating the stuff with some paste wax or maybe covering it with with some rattle-can acrylic lacquer?


                    Hi Chuck. I've not tried anything beyond the initial "wash" thus far. NASA suggests applying a conformal coating (at least 2 mils) of Arathane 5750. What a bother.


                      I'm hoping to have wrapped-up this little annoyance for the remainder of my lifetime - the chassis is now stripped of its zinc, and has been re-plated with nickel.