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#61
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#62
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hey wait what you trying to pull one has a hole one doesnt
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#63
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Those are two from the same set of original looms ... both looked the same before I started.
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#64
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__________________
1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#65
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For me it's been three different things that can cause that. I use a formula with a lot of the zinc sulfate powder in it, if you are using one of the formulas that depend more on the zinc electrodes then they can be pretty finicky about their composition ... if you are plating large items like pulleys it can deplete any zinc in the solution pretty quickly. Might try dumping in some more zinc sulfate if you have any.
Next cause would be part preparation .... I get kind of lazy here sometimes. I always dip in muriatic acid to clean off any old zinc and rust if it's there, then bead blast .... when I've skimped on the bead blasting it usually has bad results. Old solution .... the formulas that use more organic stuff seem to go off quicker, whereas the formulas that use more "chemicals" seems to last longer. But any solution should last a couple of weeks for sure. I'd guess you may be running your solution out of zinc. Most of these formulas are far from optimal for efficient plating, if you are using only zinc anodes and no sulfate, and doing larger parts .... that is hard for the anodes to replace fast enough to plate efficiently. I use both, lots of square inches of anode, and the zinc sulfate. I've still found it a hit and miss proposition .... when a part doesn't want to plate I usually send it back to the acid and start over again. Also I would guess any contamination floating on the surface is going to draw down with the part as you lower it into the solution. And your description of the problem .... plating well in some areas and not others .... that would make me think contamination on the part, as typically a bad solution will plate the whole part lousy. In general it's been my experience than nothing plates as well as a batch of new solution. Try a smaller part and see if that plates ok. I'd love to see a formula for solution from a real chemist, but some of the plating forums I've visited they are far too busy laughing at the home plater than willing to offer any real advice. |
#66
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It just goes to show there is elitism in every corner.
__________________
1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#67
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Yeah, I don't really get it. Most DIY'ers just go there to ask if they might be a to come up with a decent formula that a home user could put together without too many industrial chemicals. Something better than the old standards.
You would hope they would want to show off their knowledge by being helpful, but instead they'd rather berate people for not having a PHD in chemistry. Anyway ... 68bird .... might want to check the solution PH too. Something I don't do nearly enough, it can cause big problems if it's too far off. Most recipes may include instructions on how to adjust the PH if it gets too far off. |
#68
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__________________
1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#69
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I know the acid in the vinegar is absolutely critical to the plating process and my guess is it gets neutralized pretty quick reacting with the anodes ... come to think of it, that's probably the problem I have most of the time when the plating isn't working right. I bought the roll of litmus ... but I don't use it very often.
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#70
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Looks like I am back in business. I scooped out about 6 cups of the bath and replaced it with pure vinegar and added another 100 mgs of epsom salt to replace about what I probably took out. The original mix was around 10% vinegar. I think I am at somewhere around 25% vinegar now and it is looking really good, even better than the original bath since I am not getting the weak spots I was before.
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1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#71
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Good to know ... probably the same thing that makes my solutions go bad.
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#72
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Been doing a little more research. I found other articles that say to have a Ph around 5.0 to 5.3 and another that says 5.0 to 6.0. I also learned that distilled water which you would think would be neutral 7.0 could be lower (more acidic) as it absorbs carbon dioxide after it is produced. Anyway most things are looking really good except for alternator pulleys where I can't get the zinc to plate down in the belt groove. I did one before with the original formula and that came out fine, but now I am getting this issue. I tried more power, less power, agitation, and no luck. Have any of you platers experienced this before?
Picture below. This is fresh out of the plating and dried. I did not brush off the coating yet but you can see where it plated and where it didn't.
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1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#73
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Did you bead blast down into the groove prior to plating? That area can get a little polished and work hardened of course.
What did you use to pickle it? Might need something stronger like Muriatic acid. However, I wouldn't be very upset about that ... the zinc in the groove is going to wear off pretty quick in use. |
#74
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I even did a few long alternator through bolts where I polished them with a wire wheel first and they turned out really nice.
__________________
1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#75
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When all else fails I always bead blast again ... just something about the finish on some pieces of metal that seems to defy plating without some serious mechanical cleaning or texturing.
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#76
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Was doing some small screws today ... like headlight adjusting screws.
Using a typical CC/CA power supply I found I definitely had to use a resistor, I could not get the amp down to a suitable range with a suitably high voltage and kept "burning" the plating. Added a 10 Kohm potentiometer and was able to keep voltage at 3.0 and amps down in the range I needed. Only using the first 10% of the potentiometer swing. Used it on a slightly larger part and burned up the potentiometer ... so I just ordered a 500 ohm, 50 watt unit ... that should do the trick Plating was much better on the tiny parts with the amps lower and voltage correct. |
#77
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__________________
1968 Firebird 400HO convertible 1971 Trans Am 4-speed, white/blue |
#78
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I'll give that a shot. The solution I was using was pretty old ... but stored in a opaque sealed container ... I have no idea of the way it decomposes or it's shelf life. I'm sure some ingredients degrade before others leaving the solution imbalanced in some way.
Still enjoy doing it, spent the last week trying to find some correct small hardware for my hideaway lights, gave up and just decided to glass bead and plate the original hardware. The cover pivots bolts that most people get about $35 for a set, replated my originals and they turned out great. Now that all the plating gear is out I'm having problems finding more things to plate |
#79
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Dataway - which zinc sulfate do I need to use - the 99% or the 35%? Getting ready to start plating.... Coronavirus forcing me to do it myself! I think i will be fun though!
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"I know just enough to keep me here, but not enough to get me out" |
#80
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Most of the Zinc Sulfate Monohydrate you see on ebay and elsewhere will work fine .... don't pay too much ... should be able to get a couple of pounds for $30 or less.
Most of them are in the areas of 32-35% ... if you look closely you'll probably find that the ones that mention 99% are specifying purity of ingredients, rather than actual zinc content. That kind of purity is not necessary for plating. Found another good link on the DIY process https://www.nonlintec.com/tr4a/plating/ Last edited by dataway; 04-04-2020 at 02:15 AM. |
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