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Restoring a WECo pink 500 Set - Sanding and Solvent

Started by, July 01, 2011, 02:45:30 PM

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I placed some plastic chips in a small bottle with methylene chloride for overnight dissolving. It may be my imagination, but the plastic seemed to start dissolving faster than with acetone. TelePlay: I tried some methylene on a piece of Blu-tack and it started dissolving it. I am sanding to remove the bleaching around the embossing on the shell and the handset (see earlier posting in this thread). It sands easily on the soft plastic handset. It is difficult to remove completely on the shell. If you use V30 hydrogen peroxide on any plastic parts check frequently that it is producing desired results. This may mean having to re-coat with V30 several times but you may avoid unintended consequences.



Since Blu-Tack held the acetone, that would indicate Blu-Tack is made with non-polar materials and therefore would be very susceptible to being dissolved by the non polar methylene chloride. Just as acetone would dissolve latex spackling paste.

I did a quick test using a piece of 1/8 inch black pebble finish ABS I picked up at Midland Plastic for a dollar. Using DAP latex Spackling Paste (the drywall fixing stuff), I built a circular dam on a corner of the black ABS. I put a little water in the paste so it was somewhat soupy but would hold its form when placed on the plastic. That let the paste fill in the pebble finish beneath it. I then used a hair dryer for a minute or so to dry the surface of the spackling paste dam. I then used a glass eye dropped to fill the dam with DCM. I did it outside. A gust of wind came up and some of the DCM blew onto the dam wall and ran down to the ABS surrounding the dam.

I let it stand until the DCM was fully evaporated, about 2 to 3 minutes at 75 degrees F.

I used a hair dryer again to make sure all of the DCM was evaporated. I then easily removed the still soft spackling paste and washed off the paste in the pebble finish with water.

The DCM did not dissolve the latex based polar spackling paste. The spackling paste seemed to have no affect on the ABS. The center of the dam was now smooth. The ABS outside the dam where the spilled DCM flowed showed signs of reflowing the ABS pebbles.

Seems DCM is a very good chemical to reflow surface plastic and a water based latex paste will do the same thing that Blu-Tack did when using acetone.

Pictures in order of the test are below. The last picture shows the reflowed plastic in the shape of the center of the dam. The area under the paste dam is untouched.


Thank you for the drywall joint filler idea. It will be easier to mold into a dam than Blu-tack. Your test showed that methylene will smooth out a rougher finish than I contemplated.



Here is a cropped close up of the last picture after I used a soft bristled brush and water to remove the few bits of spackling paste from within the pebble finish. This closeup shows the reflowed area within the dam and the damage, if you will, to the surface area outside the dam where the DCM was spilled but in lower concentration - just flowed off instead of slowly evaporating about 5 or 6 drops from within the dam. The ABS was tilted slightly with the corner point down so the spilled DCM on top or above the dam remained on the surface longer than that spilled on the lower left which ran off quickly.



The other side of that black ABS is smooth but with scratches and small nicks similar to what one would find on an abused shell. Being a quick and dirty test to see what affect DCM would have on the latex paste, I decided to go with the pebble finish side as an extreme test. I can imagine what misting DCM on a heated shell will do to reflow the surface as described in that patent paper. I'm still not set up to do time and temperature testing right now but this showed me it won't take much to change a finish. I'm using your air brush application when I get to that stage. What I want to check is not only reflowing the surface to get rid of scratched and dings but also to see what it will take to get rid of fading or darkening with age. I work days so it will be some time before I get to that. I wish they would have included time and temperature in the patent paper. ABS softens around or above 200 degrees F but with the  power of DCM, I'm sure the effective temperature is well below that. Also, if they used a different temperature for hard and soft ABS. Would cut down on the number of experiments to figure that out.

Let us know how using DCM worked with the dissolution of rib material and if any bubbles formed on its application. And, how much faster one must work because of the rapid softening from DCM once applied to the shell.


Quote from: jsowers on July 08, 2011, 08:19:00 AM
I have a question or two. Is soft plastic, sometimes called Tenite,  also derived from crude oil products? Isn't it cellulose acetate? More of a "green" product, to use today's vernacular? I wasn't sure, so I thought I'd ask. It would probably behave totally differently under those chemicals if that's the case. So in your tests, be sure to try some of the chemicals on soft plastic if you can. It would be interesting to see a crack repair on soft plastic.

Being relatively new to phones and just getting started on resurfacing, I find this forum extremely helpful in providing help and a head start on any project phone related. I've heard hard and soft plastic used quite a lot and found the post by Dennis Markham to be the gold standard of definitions. I also found the 3 links put up by cihensley ( ) excellent. Pages 15-16 of the 3rd document ( ) lists the chemical mixture for chemical polishing of tenite, soft plastic and the methods used to chemically polish surfaces. They are all polar and less toxic than the methylene chloride (DCM) that works so well on hard plastic (ABS). The question I have is what form of tenite did they use, the acetate or butyrate/proprionate types. What I do see is there is both a chemical difference in tenite vs ABS and the "chemical" of choice for surface refinishing depends on the shell material. We can test soft plastic with DCM and the acetone based mixtures. I'm still waiting for cihensley to post the results of his using DCM to dissolve rib material to fill that crack in his pink phone. To see if bubbles were eliminated and if any other problems developed.

Here is the pink 500 with the methylene dissolved plastic covering the defective area. I did decide to roughen the area with with a diamond tip burnishing bit in the Dremel tool. I pre-wet the patch area with methylene before "painting" the liquid plastic. I also placed the patched ares under a heat lamp for 1.5 hours. I will sand tomorrow, and see if there is any problem with air bubbles.

I sanded the side of the white 500 test set (see post earlier in this thread) then used the airbrush to spray it with methylene chloride. The result was not satisfactory. It did shine the plastic somewhat. but I don't think the airbrush produces the volume of methylene needed before it starts drying. Using a regular spray gun would seem to be overkill and would lose a lot methylene in over spray. I will try a Prevel sprayer. The WECo patent calls for 30-50% trichloroethane to be added to the methylene. This missing ingredient may help, but unfortunately is very difficult to get. It manufacture was outlawed in the late '90s because the government implicated it in ozone depletion. I found a couple of sites that list it but they said they were out of stock and may not have more for several months. There were several Chinese companies that listed it as available but required ordering in "rail car" quantity. I will try to determine if there is a substitute for trichloroetane.


Quick question for our resident chemist - could (should) MEK play a part in any of this? Methyl ethyl ketone used to be common in electronics shops and production facilities because it would clean excess solder flux off joints very quickly, and then was itself easily cleaned off the joint. It is still readily available locally and inexpensively. It is water-soluble, which would aid cleanup, and is used for solvent-bonding some plastics (polystyrene? others?)



Yes, it will. I am still experimenting with filling the crack. I still got air bubbles when I used methylene. Although it is close to acetone (which also caused air bubbles) I plan to try the technique with MEK. With acetone or methylene it is possible to eliminate visible air bubble with repeated applications of the dissolved plastic. But microscopic air bubbles remain. Although they are not obvious, their effect is to lighten the crack patch so it doesn't totally blend-in with the surrounding area. A solution is to use a mold making vacuum chamber on the liquid plastic before applying it. But these cost $400-$600 so are not a practical solution.


While I continue experimenting to find a magic elixir to fix better a crack in hard plastic, I restored the handset cord. See the first picture in this post for a before. I cleaned the cord using the jsowers method and then dyed it according to the directions post by Dan/Panther about two years ago.


An update. All three solvents (methylene chloride, acetone and MEK) produce bubbles in hard plastic patches (I didn't have the same problems with the 500Us I restored). The bubbles are formed by the evaporation of the solvent in the dissolved liquid plastic. I tried a new technique that seems promising. Instead of using a solvent to dissolve plastic chip (from reinforcing ribs inside the phone) in a small bottle, I wet the area to be patched with solvent using a small brush and wet an area (with a 1 to 11/2" natural bristle brush) between two ribs on the inside of the phone. The wetting with solvent makes the plastic soft. I then used the side of a box cutter blade (I dulled the cutting part of the blade before I used it) to scrape some soft plastic from the area that I wet inside the phone. I then buttered the plastic into the crack grove. It appears that less solvent is in the plastic this way - therefore no bubble problem. In the picture of the pink shell you can see the patched area with the old and new techniques. Without the gas bubbles the fill color better matches the rest of the shell. I will now "Dremel tool-out" the old fill and patch with new fill. I used MEK for this patching because it has the lowest vapor pressure of the three solvents.

I have not had any success with solvent polishing like described in WECo's patent. I tried a Preval sprayer rather than the airbrush to get more volume. The Preval produced some gloss if I got a particular area very wet. But this would produce runs in areas I wasn't spraying. I believe the WECo method sprayed a much higher volume of solvent on all parts of the plastic at the same time. Any ideas on how to do this? Also I have been unable to find a source for 1,1,1 trichloroethane which WECo mixed with their methylene chloride.

The picture of the blue shell shows the ability of the solvent (MEK in this case) to remove discoloration. The discoloration was removed by a cheap 11/2" natural bristle brush in about three swipes. Using a good quality brush should result in fewer brush stroke marks.

The picture of the white shell shows discoloration removed by MEK then sanded to remove the brush marks.

Using solvent to remove discoloration seems to promise a quicker way to restore then just sanding alone.


Patch completed and sanded. The new technique for softening plastic for patching (see above) seems to work. A slight amount of ghosting where the patch is. I guess the solvent changes the crystalline  characteristics of the plastic.


The picture I meant to include with the last post.


Dennis Markham

Chuck.........Wow!  Fantastic repair and restoration of that Pink 500 housing!

Further experimenting. I sanded the caps with all grits of micro-mesh then sprayed them with MEK. I used a Preval sprayer and more than dusted with MEK. I got them wet but not to point that there was a danger of runs. These were not buffed. The MEK seemed to eliminate the fine scratches remaining after the 12000 grit micro-mesh, thereby imparting a gloss to the surface.