'67 horn relay finish

[Barbara S.]

I'm in the process of preparing to install my new engine compartment wiring harness and I've gotten to my horn relay. I have the original Delco Remy horn relay. I'm wondering about the correct finish on the upper metal lid. I can best describe the finish of the lid as a dull zinc finish. The JG states that the lid is cad or zinc plated, but it doesn't say anthing about the level of shine or lack of shine. Is the correct finish on a '67 horn relay lid a dull zinc or a bright shiny zinc?

Any help would be appreciated.

Thanks in advance.
Tony

[Joe L.]

Re: '67 horn relay finish

Tony-----

I believe that the original relay covers were a "dullish" zinc finish. Of course, one has to consider the fact that the "dullish" nature of the finish might be due to oxidation over the years rather than them being that way from the get-go. However, I have several of these relays in the original Delco pull-string boxes. Some were unopened when I obtained them. Every one has a dullish zinc finish. It is possible that even those in the boxes changed with oxidation over the years (after all, air does contain oxygen). However, I really believe that they were always just about how they appear now.

[Mike M.]

Re: '67 horn relay finish

i agree with joe. mike

[Barbara S.]

Re: '67 horn relay finish

Thanks guys. It's great having two "answer men" to help. I lightly rubbed some xxxx steel wool on the cover to remove some of the dirt and it just stayed that dull zinc finish even after I removed the years of whatever it is that built a thin film on it.

Best regards,
Tony

[Mike M.]

Re: '67 horn relay finish

the dull cad covers were used on other GM cars of the 60's. seems like late 60's and early 70's caddys and corvairs blew enought oil on them, based on their location, that examples from these cars serve as donors for the horn relay cover. check out the salvage yards guys. mike

[Peter L.]

Re: '67 horn relay finish

Tony - Probably a combination of dirt and zinc oxide. Pete

[Gerard F.]

Here's one freshly zinc plated

Tony,

I think they started out as bright zinc just like most other electrical parts.
But it doesn't take long for zinc to oxidize and go dull. Uncoated in a moist environment it will dull out in a couple of days. I usually give then a shot of WD40 or Triflow to save the luster, but they seem to dull out over time anyway.

Jerry Fuccillo
#42179

[Barbara S.]

Re: Here's one freshly zinc plated

Hi Jerry. Thanks for taking the time to post your photograph. Right now, I'm leaning toward Joe and Mike's version: the horn relay started out a dull gun metal zinc. Obviously the oxidation process over time is a difficult variable to judge since all of the original horn relays are the same age and subject to oxidation. However, Joe indicated that his original, unused relay lids have the same dull look as ones actually used in cars. Also, other (non-horn relay) zinc or cad parts on original cars that started off with a bright finish seem to retain some brightness. Wouldn't bright zinc parts be subject to the same oxidation process as these horn relay lids? I've never seen a bright zinc horn relay lid on an original car, but I have seen bright zinc (non-horn relay) parts on original cars. Why would there be a difference in finish if the horn relay lid started off bright as known bright zinc parts did as well?

From its birth until May of 2005, my car was an East Texas car. It was parked in 1981 and there it remained until I purchased it. The original parts were in good condition. Even the original body stencil was clearly visible. My horn relay has that dull zinc look like Joe described. I realize that time could have changed all that, but my gut feeling is that it probably has always been a dull zinc finish. You have a bright lid. How long has it been on your car? Has it dulled over time? How does it compare in brightness now to when it was first replated? Maybe you can help answer the oxidation question by comparing how your lid looked when it was freshly replated and compare it to how it looks now. Even though your lid started off bright after the plating process, is it a dull zinc now? If so, how long did it take to change to a dull zinc finish?

Thanks again for your input. There is not always an easy answer to the questions we raise in here. I just want to make the best decision I can to make my restoration as correct as possible.

Best regards,
Tony

[Peter L.]

Re: Not all Zn Plating is created equal!!!!!!

Tony - Interesting questions and while most plating process produce a similar outcome, there are enough variables that like building car engines with all those parts, it's "amazing" to a non-engineer that they run and that they keep running for hundreds of thousands of miles at relatively high RPMs, of course there are a few that don't. Not a perfect process. Gerry has a great system and he can change and adjust parameters to produce the outcome he wants; but if you are Delco-Remy and the horn relay covers come in a little brighter or duller you don't stop production for lack of a cover that folks are going to judge 40 years down the road. Another experiment to try is to take some covers to different platers and have them all do the same process and what you'll find is some platers do a great job and there will be some you won't want to use again. So, if it looks like Joe's or Jerry's and you find it meets your "standard," go with it. Bottomline is everything has to deal with getting old, even zinc plated horn relay covers. Have fun and toot your horn when you drive by. Pete

[Gerard F.]

Re: Here's one freshly zinc plated

Tony,

If you have it off the car, take a look at the finish of the inside of the cover. That's probably close to what it was originally, as the inside is more or less sealed.

I have only the replated one on about a month or two and it is still a little bright as I coated it with WD40. It has dulled some. However considering the position it is in, it will over time get that dull zinc oxide look. I could advance this look by dunking it in a baking soda solution or light base and let it dry.

Here's what it looked like before:

Jerry Fuccillo
#42179

[Barbara S.]

Re: Here's one freshly zinc plated

Jerry, et al:

Thanks for taking the time to share!

Toot Toot Tony.

[Jack H.]

Another opinion...

When I find relatively well cared for Corvairs in the scrap yards (good fitting hood and intact weatherstips), the horn relays are relatively bright in terms of their zinc plating. Bright to the point I'd call the original plating 'as taken from plating bath' meaning no post plate polish operation.

Oddly enough, I've also seen NOS originals (in pull string box) that were badly oxidized, however I've yet to see an original in its pull string box where the string hadn't been pulled (a 'virgin')...

Platers refer to brite and dull finish with the difference being how fresh and uncontaminated the electrolyte bath is, how slowly or quickly the zinc/cad plating is applied and whether or not the part is polished after plating. If you SLAM plating onto the target surface, the molecular layers construct unevenly giving that dull surface finish. But, if you plate slowly with just right control of temperature, drive voltage and tank current, parts will come out of the bath bright and shinny appearing to have been polished.