Author Topic: Bakelite Repair Advice  (Read 25243 times)

Offline TelePlay

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Re: Bakelite Repair Advice
« Reply #30 on: July 21, 2013, 11:24:07 PM »
I went looking for where the jumpy screen was discussed and was surprised to find the discussion right here in THIS TOPIC! Go back to reply #4 and then Bill nailed it in reply #6.

Small world, eh, Terry?

Thanks for finding it, right under our cursors, so to speak. This will help me, and hopefully others, on my older, limited memory running versions of Windows where I have that problem. Seem to recall those are the machines where I've had that problem.
            John . . .

              

Offline rherber1

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Re: Bakelite Repair Advice
« Reply #31 on: October 12, 2015, 09:44:47 AM »
My two cents worth on this subject...

For those who may live in Australia, or the UK  or indeed anywhere the products so far mentioned may not be common...I have experimented with repairing bakelite phones over many years and have  come up with a very simple method which does not involve tinting the filler material.

For simple cracks I use a good cyanoacrylate (superglue) such as Loctite 495 which is a universal instant adhesive. As has been mentioned any exposed glue will polish up quite shiny but depending on the visibility this may not be a problem. This glue is also a great filler for cracks in plastic (ABS) phones.

For chips and major repairs I use a product called Milliput http://www.hobbytools.com.au/putties-fillers-or-epoxy-for-modelling/

This is a UK product but should be available elsewhere.  It is a 2 part epoxy which can be obtained in different colours. Obviously bakelite is black so go for this item. Small chips don't require support formwork but larger areas will do - this has been covered in  previous answer. One major advantage of Milliput is that it is water soluble when mixed so it can be easily smoothed and shaped over with a dampened knife blade or other sculpting tool and when cured it is rock hard and can be filed and sanded. One thing any filler can't do no matter what you use is to correctly match the original colour of the item being repaired so painting is a necessary part of the final process.

The best paint for finishing bakelite is Anchor brand gloss black spray lacquer http://clampline.com.au/product/read/anchor-lacquer-gloss-black-300g/3796/

I haven't a clue whether it is available in the US or UK but I assume that it is - or at least a similar product will be. The beauty of this paint is that it is so easy to use without any of the problems I have experienced with other paints - such as orange-peeling due to some tiny speck of contaminant on the surface. Provided that you use clean water containing a good household cleaner such as Domestos http://www.domestos.com.au/product/detail/997053/domestos-disinfectant-original-125l when you carry out your final wet or dry sanding operation with 1200 grit (800 grit makes for a faster cut) https://www.carbatec.com.au/sanding-and-finishing/sand-papers-and-rolls/sand-paper-sheets/standard-sheets/wet-and-dry-sandpaper-1200-grit before a final rinse off with the hose, the painting process will go like a breeze. You must avoid hand contact on the surface to be painted. Suspend the item on a stiff wire through a convenient hole or other method so that you can move around it (or rotate it) while painting. Use a hot air gun to blow dry blow the item - around 270 deg C - and then give it a good brush over with a clean nylon bristle paint brush to remove any specks of dust.

Note: Domestos may not be available in some countries but is is essentially a cleaner/disinfectant based on Sodium Hypochlorite https://en.wikipedia.org/wiki/Domestos so I'm sure similar products are easily obtained no matter where you are. Id not then simply use an alternative and making sure that you avoid handling after the final rinse. Spray paint does not like any contaminant.

The hot air gun treatment warms the item and helps the lacquer to set quickly with less chance of runs occurring. Now If all goes well there should be no orange peeling or beading due to surface contamination when you apply the paint.  After spraying a liberal coating, again apply the hot air gun treatment, moving over the entire surface without concentrating too long in one spot. After 10 - 15 minutes of hot air the lacquer will be fairly well baked. Now allow the item to cool for a while so  you can then carry out further wet sanding if required. Give it another coat of paint if required until a perfect finish is achieved.

I have used other paints such as White Knight Rustguard epoxy and while it cures to an excellent hard surface it takes a long time to cure before you can continue work on it again - even after the hot air treatment. It is also less tolerant of any contaminants than the Anchor spray lacquer and will run more easily if over-applied in one area. It is not uncommon for me to be so dissatisfied with the end results using epoxy that I have resorted to using paint stripper to remove all applied paint and sanding down to the original bakelite surface before starting over again.

Before polishing the finished paintwork I give the surface a final wet rub-down with 1200 grit paper to remove any minor blemishes which will take a lot longer to polish out otherwise. I use a good metal polish which has a small amount of silicone in it and after buffing the finish is better than when the item first came off the production line.

On the subject of polish:
Some will be horrified and say, "never use a silicone based polish", but I find it difficult to imagine how the infinitesimally small amount of silicone remaining after buffing the outer surface of a bakelite telephone casing, can travel all the way inside and then make its way into the internal electrical contacts where it may be subjected to arcing, and thus cause a problem. Sure, I know it did happen when silicone based lubricants were used way back in the late 60's in exchange switching equipment, but the amount of silicone in those products was huge by comparison and it was fairly liberally applied by careless techs. It is no wonder it migrated everywhere and caused contact insulation problems. Indeed, there was a very good reason for banning its use as a lubricant around electrical contacts, especially when it was being applied in this manner. But in a small concentration in an external polish which is finally buffed away I think it is stretching a long bow to suggest it can cause a problem in a telephone - I know it is possible but I doubt it would happen. Anyway, if the phone is purely a collector item then it hardly matters.

Offline RotoTech99

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Re: Bakelite Repair Advice
« Reply #32 on: October 18, 2015, 06:54:30 PM »
JB Quick Weld is also good for repairing Bakelite and early thermoplastics, particularly
if they are black in finish...

It dries to a black color and sets in a hour, curing after 24 hours and may also be sanded, painted.

Only particular word of advice is it begins bonding quickly, so be sure you get it where you want it to be fairly quickly.

Offline cloyd

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Re: Bakelite Repair Advice
« Reply #33 on: May 07, 2016, 04:32:04 PM »
Phone-sweep,

I read with interest your post on CRPF regarding repairing bakelite with dyed Bondo resin.  First of all, well done!  I want my repairs to look like that!  I am going to start practicing this afternoon.  I am going to try India Ink as my dye and see if the Bondo resin will solidify.

My question is about the finish on the spit cup.  It started out chipped and brownish and ended up smooth and glossy black.  I understand the principle behind repairing the chip but how did you get rid of the brownish color and make it glossy?  If you are willing to share your trade secrets, I will do my best to replicate the effect on the phones in my tiny collection.

Thank you,

Tina Loyd
-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- 1885