ageing a pedal with hydrochloric acid. thoughts? deep thoughts...

[darron]

i'd like to make a pedal that looks authentically 50's.

well, first thought is "i just can't make it look authentic". you open up old gear, and it's just not the same. everything's made of bakelite, and everything has dulled and corroded. i've got the 50's parts like resistors, wire, semiconductors, caps pots switches etc. but my enclosures and jacks etc. all look new. i'd have to destroy something to build something - no good. (well, i suppose i could find some vintage jacks on something dead...)



then i remembered that i rusted the crap out of all my gear by accidentally leaving a vat of hydrochloric acid open. everything in a 5 meter or so range turned brown and dull. my cheap behringer PA was nearby and all the component wires inside it now are crunchy. still works though! no damage to the pot carbon tapers or anything....



i've looked it up in google and people are indeed using this method of leaving metals over the fumes of hydro acid to rust iron. not much info on electronics use.



i'd like to give it a shot. i'd like to know what best plan of attack you guys might use.



the resistors + caps and pots all look aged, so its best i leave them out.

i'll use some waxy cloth wire. no need to oxidise the inside of that i don't think. so i think it's safe to add the circuit board with wiring very last in-tact.

what about the solder joints such as on the jacks etc. will they benefit from some oxidisation? i should probably use a nice dull leaded solder to make it more authentic too... some of the joints that have survived from then are very dull.



here's the biggest one: i'll use a new carling DPDT. i'd like to age that, especially the visible top but i REALLY don't think i'd like the fumes getting inside the contacts!! would it seal itself well enough to hold up in the long term with use? would i be able to seal it well enough perhaps with some detergent goop or something? i'd really like to have a massive 60's car headlight dipswitch or something but can't find a nice dpdt. i'm thinking just go for it.... if its a brand new switch I'm hoping the oils might protect it?



also, if the jacks get aged, would it be good enough to use the switchcrafts that i intend and then just brush back the contact points and clean them up? i'm thinking of putting a blob of solder on the hookup areas and sucking it off after "ageing" them and doing the wiring later. that way i wouldn't have to brush back the hookup area and have it look unnatural.



i'll probably use a folded steel enclosure that's been powder coated that a friend gave me. it should age a lot better and look more authentic than aluminium.





does anyone have any tricks to make plastics look aged? for example it would wreck it a bit if i added a 2.1mm socket and a new rubbery battery clip. i hope maybe i could make plastics look old by first making them dull with steel wool and then kicking them in the mud in the back far for a while... or something... or rubbing some incense ash into them.... or... or...?



this is a similar enclosure:










should i ding the edges a bit too before rusting the pedal?

[alparent]

When I was into scale modeling. (NO I wasn't a midget super model!)

We would use Future/Pledge floor polish (just wet with it but don't polish it) to dull down the rubber tires.
Also talk powder to simulate dust.

Look at scale modeling sites for great tips on aging things.

[boogietone]

I would be careful letting corrosive agents near electronic parts, switches and jacks included, unless you are looking for that scratchy vintage vibe, of course .

[Tpetty5]

Research aging guitar parts.  A lot of those techniques would apply to stompboxes.

[darron]

I would be careful letting corrosive agents near electronic parts, switches and jacks included, unless you are looking for that scratchy vintage vibe, of course .

but not ageing the hardware defeats the purpose.... i wish there was a way to protect the critical contact points. hopping a post-cleanup might do it? lots of work i know (:

Research aging guitar parts.  A lot of those techniques would apply to stompboxes.

i found that afterwards. i wasn't searching well. "relic" "relicing" were the words i needed. those guys can get pretty aggressive with their way though, covering parts with etchant sometimes! i don't think it always gives them the most authentic results. I did read one about a guy suspending his nickel hardware in a large bucket over a smaller container of hydrochloric before posting which is what i had in mind - pretty much.



i guess nobody listening has tried this to the extent that i'm thinking.... maybe i should make a tech doco on it if it works (:

[jafo]

should i ding the edges a bit too before rusting the pedal?

Yep. That way you'd get old-looking rust as well as old-looking paint. Also, you prolly don't want new-looking dings. Well, maybe a few.

I was also thinking that maybe you could cover certain critical parts with tape or something to keep them protected while the rest of the build gets exposed, then maybe uncover them for a little bit of exposure at the end. That way, they'd look older but won't be as damaged.

[joegagan]

i went to my battery in my van for acid in this etch. i dipped a paintbrush right into my battery to apply in certain areas on this wah. you can tell, it has a greenish cast in those areas.

only left it on for a few minutes, then washed with detergent. about 4 coats of nitro lacquer over top locks it in.

[joegagan]

^^ i didn't use the acid to remove paint, that was all done by previous owners or me with knives and polishing. i only used the acid to dull out the polished areas.

[John Lyons]

Don't "fume" anything. Just brush on dilute amount and make tests on parts you
won't use. Used H2o2 and Muratic acid will semi copper plate steel so if you don't want that use
weak new etchant. Ferric Chloride will etch off chrome/nickle.
Steel wool will buff things out nicely. I believe vinegar will dull solder joints (maybe be in combination
with something else though so...)
Carefully brushing on to the foot switch will help no affect the critical areas.
Hard to see the details but this was done as mentioned above. I didn't take it too far...

[markeebee]

I believe vinegar will dull solder joints (maybe be in combination
with something else though so...)

Vinegar mixed with salt is good for relicing plated parts (and good with fish and chips).  Although if my pretty non-existant knowledge of chemistry is correct, vinegar+salt makes weak hydrochloric so maybe it's not worth the hassle of mixing them if you already have the real thing.  And by 'the real thing' I don't mean Coke, that doesn't work half as well.

An old relicer's trick is to put metal parts in a cardboard box with a load of small screws and then shake it about.  Takes a lot of shine off, and adds a few small random dings. 

My guitar-tech mate says that a good way to relic metal parts is to wee on them and bury them underground.  I think that either he was winding me up or he was confusing 'metal parts' with 'dead bodies'.

Oops.

[joegagan]

john, i gotta say it again, that is an amazing looking box.

[darron]

thanks guys!

i've got twice as many good thoughts now!



i didn't even think of good old salt. it's funny, because the gear i've seen with the roughest life i always think looks like its spent 20 years bumping around the bottom of the ocean. i wonder if i could even get a bucket of water from the ocean and leave the enclosure in there (not the switches etc.). it would make a nice story.


sounds like you're right on not using fumes John. it's VERY hard to control where fumes will not get into - near impossible for the work i'd like to put in. all the painted etch work i saw was MUCH too aggressive buy having seen your work it looks like it's entirely possible to do it in a nice controlled way.



i think i'll try the bucked of screws trick. i was wondering what might be the best way, and the screws might be small enough to not look to intentionally forced.

i'd take the backyard trick seriously. like i said, i might kick it around the mud a bit. maybe i could burry it in a full moon

can't wait!

I might try to make a video or photo tutorial if it works.

[Earthscum]

+1 to Mark's trick, EXCEPT... you don't even need the salt.

There are actually paints that have iron embedded in it. After you spray it, yo use a vinegar mix to "rust" it, and then use the sealer coat. It IS an old hot rodder's trick, for sure.

Vinegar works fast, btw. it isn't like working with hc acid, but you still have to watch it. If you don't rinse it all off, it can continue to eat away under the paint, etc.

You want to mimic a crusty inside? Use a gray primer and "dust" the inside (components and everything).

Of course, don't forget your vintage cloth covered wires (I'm sure you're way ahead of me on that).   

[boogietone]

The role of table salt (NaCl) in these weakly acidic solutions, such as vinegar, is an indirect one. The salt is there to increase the electrical conductivity which allows the actual corrosive agent (an oxidizing agent in this case) to act at faster rate than it would otherwise. The diffusivity of the ions themselves is also part of the rate limitation, but the conductivity increase due to the addition of the salt is important and can be several orders of magnitude.

Adding table salt to water or to an acidic solution will in most cases only lower the pH by a couple hundredths of a pH point and does not alter much the oxidation-reduction chemistry - the rate yes, the chemistry no. This is the chemistry of most chloride salts - with the very clear exception of ferric chloride.

In the case of FeCl₃, it is not the chloride that drives the pH down but the iron which "consumes" hydroxide (-OH) ions through the formation of multiple iron hydroxide ion complexes. The advantage of using iron chloride is that chloride salts tend to be the most soluble and are pretty cheap to manufacture.

Ultra pure water actually has a very low conductivity on the order of 5.0x10^-08 (18 MΩ-cm). Conductivity is the usual measurement of purity of water. On the other hand, a typical 5%(wt) vinegar solution has a conductivity of 1.4x10^-3 S/cm (730 Ω-cm). Adding 1%(wt) NaCl increases conductivity to 1.8x10^-2 S/cm (55 Ω-cm) and 10%(wt) to 1.2x10^-1 S/cm (8 Ω-cm). For further comparison, a 1%(wt) solution of HCl (no salt added) has a conductivity of 1.0x10^-1 S/cm and the typical full strength 40%(wt) FeCl₃ solution used for etching has a conductivity of 4.6x10^-1 S/cm.

Thus, soaking a metal part in a salt solution increases the rate of corrosion generally not because the salt itself corrodes the metal but because the salt provides an lower resistance pathway for completing the electrical circuit of the redox reaction that does the actual corrosion/etching.

[PRR]

> the conductivity increase due to the addition of the salt is important and can be several orders of magnitude.

Thank you!

I used to clean copper-bottom pots with vinegar and salt. Brings-up the copper shine (quite opposite to what this thread is supposed to do). I never knew why it worked.

[defaced]

Thus, soaking a metal part in a salt solution increases the rate of corrosion generally not because the salt itself corrodes the metal but because the salt provides an lower resistance pathway for completing the electrical circuit of the redox reaction that does the actual corrosion/etching.

Hmmm, now to try this the next time I etch a board/box.

[anchovie]

When I used to have my workshop in a garden shed a snail got in, ate most of a printed schematic and slimed all over a Hammond box.

I've never been able to scrub the tarnish off!

[markeebee]

^ Ah, that's like my worst nightmare.

I have a real pathological loathing/fear of slugs and snails.  They really have me right over, they are the devil's poos.  Sometimes they slime their way under the door and into my workshop - if I'm in there when they get in I have to ring the house on my mobile and get my kids to come and rescue me.

But....I recently had a bit of an incident with a tub of ferric, and it instantly reliced the paint on the floor (take note, Darron) and - BONUS - I've never seen a slug in the workshop since.

[frank_p]

^ Ah, that's like my worst nightmare.

I have a real pathological loathing/fear of slugs and snails.  They really have me right over, they are the devil's poos.  Sometimes they slime their way under the door and into my workshop - if I'm in there when they get in I have to ring the house on my mobile and get my kids to come and rescue me.

But....I recently had a bit of an incident with a tub of ferric, and it instantly reliced the paint on the floor (take note, Darron) and - BONUS - I've never seen a slug in the workshop since.

I have the same fear and my grandma told me this trick:
Just put a bowl of beer, they'll go drink and fall drunk and drown in it.  Just take care that you or your childrens don't do the same.
Then you can fry them in butter and garlic. (not your childrens) and eat them with your fish'n'chips.

[boogietone]

Then you can fry them in butter and garlic. (not your childrens) and eat them with your fish'n'chips.

Mon beau-père has a special grate for his grill to cook them hundreds at a time.