National dial discoloration..

[wb1ead]

Hi all..in the midst of restoring two different National rcvrs..sumptin has always puzzled me..anyone familiar will know that it's quite common to find a sort of hazy yellowish-brown discoloration to the "circular" dials in many of the earlier National models..it's not as common if at all on the "slide rule" type..is this some sort of a chemical reaction to air/sunlite?..is it the type of paint/coating applied there?..can it be safely removed/restored?..and lastly is there someone out there who specializes in restoration of these dials?..I know it's been discussed in a kinda offhand comment but to my knowledge not in depth..true not just Nationals suffer this fate as I've seen this on other manufacturers rigs too..call me Mr Curious but inquiring minds wanna know..thanks!

PS: if there is a "solution" to this..it would be nice if this was moved to the "restoration" forum for others to learn as well..restoration for myself and I'm sure for others is more than electronic..the exterior/cabinet part is very important too..
                                             tnx!..73 de DAVE

[k4kyv]

Some of those old dials were made of a composition material like celluloid. It naturally yellows with age and UV, much like old newspapers.  Eventually it may well disintegrate into a powder, just like the plastic spacers on old air-core plug-in coils.  If the markings are still legible, I wouldn't worry about it. You probably can't clean it off, or if you do, it requires eroding away the "skin" of the plastic and it won't ever look right.  That's just part of the patina of an old piece of equipment. Sometimes collectors will pay more for a trophy unit when it is left as-is than if it has been even successfully cleaned up to look like new.

I once bought a circa 1935 HRO that had the original German Silver dial, not the black enamel one.  The seller sent a note saying he had "cleaned up the dial for me" before shipping it.  He used a fine-grade emery cloth or sandpaper, and managed to remove the tarnish - along with most of the plating on the dial down to spots of bare brass, as well as to partially erode away the dial calibration markings. Speaking of the urge to kill... I guess there is no cure for stupid.

[Todd, KA1KAQ]

Don has covered the plastic/celluloid issues pretty well, Dave. Since you didn't reference a specific model and referred to paint or coating being applied, it's tough to know for sure what you're referring to. I've got a nice NC-2-40D with metal painted logging dial that has a slight greenish-yellow hue to it. Looks to be original from the factory, perhaps an early shellac-type clear coat. National also MFPed a lot of stuff for WWII use, some of which showed up in post-war sets. Otherwise it could be good ol' nicotine.

Most of the National plastic dials appear to have been of later/better materials without the typical dark yellow/amber coloring seen on something like an old SX-28 or pre-war console dial. That doesn't mean the newer materials were any less prone to aging, more that the signs will just be different. I see a lot of newer dials that wrinkle and warp due to thinner materials used.

BTW, how are those dipoles for the low bands coming? 

[w1vtp]

I had a similar problem with a SP-100.  The solution for me (although the purist will not like this) was to have the PC boad guys at work make a photo copy of the dial and transfer to a Epoxy G-10 copper clad board of proper thickness.

Actually, I liked the green appearence but, again, the purist will not like it,  Bet it lasts forever

Al

[W1UJR]

Hi Dave,

A few comments, the other fellows hit it pretty, esp Don's comments on plastics.

Some discoloration I think is due from the heat of the backlight bulb, not all the dials seem to sufferer from the malady, so not convinced it's just aging, may be environmental as well, have cleaned much yellow residue from more than one set.

You mention circular dials, NC-173/183 perhaps?

I may be able to help you with the repo dials. Some years back I had a fellow make up new dials for some National FB-7 receivers I was restoring. Some, but not all, had very yellowed and brittle dial scales. The company was Rock Sea Enterprises, think they have since sold to Radio Daze. The fellow, think his name was Mike, was very!!! helpful, just scanned in a copy of the dual and he dressed it up, finihed product quite authentic and very reasonable. if Radio Daze can't help, perhaps you can track down Mike. If you are working on a FB-7 , then you are in luck, I should have at least one spare.

Rock-Sea Enterprises
PMB 241
323-110 E. Matilija St.
Ojai, CA 93023

(805) 646-7362 dials@juno.com


What I wonder, speaking of yellowing, is if all Johnson Ranger and National HRO scales were yellow, or is that an age thing as well...

Bruce...another Mainer

[Todd, KA1KAQ]

I had a similar problem with a SP-100.  The solution for me (although the purist will not like this) was to have the PC boad guys at work make a photo copy of the dial and transfer to a Epoxy G-10 copper clad board of proper thickness

You could actually get enough light through to read it, Al? That stuff is barely translucent compared to the white plastic dials used on the Super Pros. I've never had problems with those, but I recently picked up a nice RME-69 to replace the one I sold back in the early 80s, and despite looking good from the outside, the dials are wavy as hell right around the bulbs. On the RME, the needles move instead of the dials. Apparently a different type of plastic compared to similar celluloid type dials of the day as they don't discolor. They still have a nice, creamy tan color to them. And the #$%^@! numbers are microscopic!

[wb1ead]

Thanks all fer the replies!..didn't answer sooner as even though I'm retired momma ALWAYS has a "to-do" list waiting..yup the minute I read Don's comment regarding "celluloid" it all dawned on me..of course..too bad there were no "aging" tests done by National and others back when..thank you Bruce fer ur tip on Mike..I think I perused Radio Daze for that earlier and saw some dials but not mine at that time..yup right on..it's the venerable NC173..183's little brudda..and two other models with just the S mtr discolored..there is a tie-in to the dial lamps as this "oddity" is seen on various other rigs gone thru here usually on an edge area or so where the bulb is closest..it's probably a combo of celluloid compounds/UV lite/and everyones villain nicotine..Don's thought on ruined dials after cleaning or attempts to are probably very right on
        I guess Mr Curious is satisfied..thank you all agn..Al 'VTP you were strapping the other day on 3880..coulda swore you said NH as the QTH though..??..Todd when we talked at Nearfest..I DID hear ur comment under ur breath "heck we'll all be gone by then..." when ya asked the same question.."how's them OCFed dipoles coming?.......I DID chuckle about that buuuuttt yes they are now cut to size(wire)..the balun is here..4/1..even the tie-off points are set..hopefully somehow I can wean myself away from constant "wishin and hopein" the 10mtr band will come to life..2 yrs of dismal HAS taken it's toll but I do move painfully slow..
                                           73 de DAVE

[Todd, KA1KAQ]

Heh, and I thought I was being so sly. 

Dave, I'd be willing to bet that National never worried one bit about aging tests for their dials anymore than Edgar and the gang at Johnson did about their lack of paint prep for cabinets and panels. Why? Because none of them in their wildest dreams ever thought the gear would still be around now, muchless used, restored, and enjoyed by generations who, in some cases, weren't even born yet. Manufactured obsolescence hadn't become the driving force that it is today in consumer products, but the march of technology was outdating much of the stuff within a few years. Then the plastic radios showed up and it was pretty much game over for most of the big, metal boxes.

I can't give you too much guff about the aerial situation there as my 40m is down for a rebuild (it's actually up in VT waiting for me to pick it up) and the transmitters are currently on hiatus (again). But yes - 10 will come back someday, and it will be fun. 40 is at least a manageable size half wave dipole that you can fling up quickly and be on the band. And there is always something going on there. And once you get on 80, you'll be pretty well set with bands to use while 10m makes up its mind.

Good luck with the National dials, and if we don't catch up on the air, we will at NEAR-Fest. We can go raid Al's vehicle for goodies when he's not looking! 

[KM1H]

I dont believe that the old NC-173/183 National dials were ever a clear non color, never saw one anyway and others who bought them new have said the same thing.

The celluoid dial covers are entirely something else and repops are available for the NC-240D and others.

Carl

[wb1ead]

Say Carl I don't dispute that one bit..ur the one with most background on National..however having a heap of the ol' QSTs and other rags here in that era..1946-1948..it just seems the pics in the ads show them dials as fairly non-colored..maybe they DID have a very slight tint that over time gets darker..methinks I'll live with it and love them all the more..for me it's the audio out of a National that I most admire..that and the "unique" panel layouts that cry "Ol' Buzzard"..at least on the stuff up to the mid 50s..

PS: Todd.yah I like that idea of hitting on Als stuff..I found out he's only a hop-skip-and jump from me..I could case da joint for ya!

[KM1H]

I dont have the time to go thru years of QST looking for a color ad but the 1948 catalog sure shows a tint.

I cant remember for sure but I recollect a comment in a review or elsewhere about the pleasing non glare tinted dial. This will give those with a lot of time on their hands to prove me wrong The NC-33 and 57 had the same tint.

Carl