Sanding and Solvent Polishing WECo Hard Plastic

[old_stuff_hound]

There is some ingredient in plastic that feeds mold (which will eat most anything, of course). Most of us have seen mold on a poorly-stored plastic phone. As Dennis observed, you can sand off the surface mold, but it will come back if you don't dig it all out, or kill it with bleach. Even after you kill it, though, the discoloration will probably remain, so bleach alone will not be the answer..

Thoughts? Chuck? Dennis?

That's interesting -- I hadn't seen that post. Maybe mold it the culprit.

By the way, don't lose track of the fact that in this thread, at least, Chuck isn't using retrobright, so thoughts regarding UV don't mean anything.

Bill

Here I have to disagree with you. He's not using UV light to remove discoloration, but years of UV light may have caused the discoloration. Also, my comment above about seeing how the mottling would be changed by retrobrite would serve as a diagnostic for determining what's causing it. If it's mottling because of UV discoloration (i.e. there's still some oxidized bromine), retrobrite would probably remove it. If it doesn't, then something else is probably causing it.

[cihensley@aol.com]

An update.

Dipping with pure acetone produced the same blotchy finish as pure MEK. Pure methylene chloride does not result in a blotchy finish, but the finish is not as shiny as with MEK. However, I was testing the solvents for their propensity to produce blotches and had not sanded with micro-mesh (regular sanding to 400 grit). I will further test with methylene chloride after mico-mesh sanding and some tests of MEK mixed with other solvents.

Chuck

[cihensley@aol.com]

After multiple mixtures, the best so far is MEK with 30% lacquer thinner. I used Ace Hardware lacquer thinner. I mention this because the proportions of solvents differ in various brand - so if someone wants to do their own test. I dipped the white handset (I will post pictures later). No blotches appeared. This is a picture of a piece of a blue 500. I sanded it with 320 and 400 grit regular paper - no micro-mesh. Further information to follow.

Chuck

[JorgeAmely]

Nice reverse-engineering work, Chuck.

[cihensley@aol.com]

Here is a tool I made, out of clothes hanger wire, to dip handset caps. Also, if even a minute quantity of solvent remains on a cap or handset threads, it can change the shape of a thread making it difficult to screw the cap onto the handset. I have found that spreading Vaseline on the female threads (with a Q-tip) and wrapping (about 3 wraps) the male threads with Teflon plumbing tape eliminates the problem. Both the Vaseline and Teflon tape will succumb to MEK/lacquer thinner solvent, but not during the short period of a dip.

Chuck

[cihensley@aol.com]

Here is the often dipped white handset. For the white, the best mix seems to be 1:1 MEK and lacquer thinner. Why the colored plastic can take a richer mixture of MEK is a mystery to me. Again, I only sanded this to 400-grit with regular sandpaper. You can see the effect of repeated experimental dipping on the threads. I made no effort to protect the threads in this experiment.

I now want to experiment with soft plastic. Anyone have an old, cracked plastic H mount that you don't want. I will pay the shipping.

Chuck

[Bill]

Chuck -

Back to an earlier question. When you dip a piece, does any of the color leech into the solvent? In other words, if I make up a batch of MEK/lacquer thinner, and dip a red handset or body, does any of the red color come off in the solvent, and if so, does it preclude me from then dipping a white handset? (Hmm.  Might be a way to make one of those rare pink phones ...).

Bill

[cihensley@aol.com]

Bill:

I have not found color transfer to the solvent to be a problem. The dip is so short there is probably not time enough for the plastic to transfer color. Also, I have found that I can dip one-half a piece; then after it is dry, dip the other end. No line from the meeting of the two dips is evident. This saves a lot of solvent. The ability to do a shell (longwise) in two dips instead of submerging the entire shell in a single dip is a 5 factor improvement in the amount of solvent required.

Chuck

[GG]

MEK safety/health data:

http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/mek/health_mek.html

In short, it's an irritant, it's poisonous to ingest but not a "strong" poison.  Use eye protection, wash hands after working with the stuff, work in a ventilated area, and don't get any in your eyes, nose, mouth, or on sensitive skin.  It's not a known carcinogen and doesn't appear to have other insidious risks.

If you intend to mix it with anything else, it is worthwhile to study the risks of each component chemical and find out if the mixture forms any new compounds that are known hazardous. 

[TelePlay]

. . . doesn't appear to have other insidious risks.

If you intend to mix it with anything else, it is worthwhile to study the risks of each component chemical and find out if the mixture forms any new compounds that are known hazardous. 

Both are flamable so ventilation is well advised.

While I will never say never, mixing similar, stable organic solvents should not cause a reaction. Paint thinner and strippers and other commercially available liquids (gasoline) are a mixture of more than a few solvents. Organic reactions require reactive organic compounds and a different type of organic reagent, and at times a catalyst,  to split or combine parts of the organic compounds that could create a dangerous new organic compound.

Working with water based acids and bases and metals are more highly reactive than organic solvents and can produce noxious, toxic and hazardous byproducts - for example, sodium hydroxide and aluminum create hydrogen gas.

Overall, good advice. Caution is always advised when working with anything.

[GG]

Flammable means: no smoking, no fire or open flames, nothing that can produce a spark, and ideally work outdoors with the breeze blowing across the work area perpendicular to your line of sight (e.g. from left to right or right to left, thereby not producing eddy currents that bring the stuff back in your face).  I have read accounts of people working with gasoline as a solvent, and then doing something to cause a spark, and ending up dead or in the hospital.  If you can smell it, it's in the air and it's a fire/explosion risk. 

If you can't work outdoors, then work directly in front of a window with a fan in the window sucking the fumes out.  If a fan in the window in front of you isn't possible (and beware sparks from switching it on!), then set up another fan in another window blowing fresh air into the room so the solvent-laden air goes out the window in front of you.

Now while we're on the subject of safety with solvents and gasoline: 

Whenever you put gas in your vehicle, ALWAYS touch the metal side of the gas pump BEFORE you start, to discharge any static electricity that may be in your body.  Many are the stories of people who didn't, and had a static spark cause the gasoline to erupt in a fire and seriously hurt them and damage their vehicle.  If you want to be most thorough about this, make up a tool consisting of a length of wire with a metal object at each end.  Briefly touch one end to the side of the gas pump, and the other end to the vehicle, at the same time, before you start.  This bleeds off any static that the vehicle is carrying, which can be a considerable charge.   These instructions are particularly important in dry climates, and unnecessary in fog and rain.   

And this isn't silly rumor, I've seen signs posted at gasoline stations about this, that were issued by the oil company that produced the gasoline.