Zincate causing acid copper blistering

[quentinv]

Hi

Got a couple of questions concerning the dreaded zincate process.

I am attempting to triple chrome plate aluminum alloy parts from a 1980's Japanese motorcycle. Using all Caswell products my process is as follows:
1. Degrease highly polished part in ultrasonic bath for about 15 mins. Scrub with nail brush.Rinse.
2. Dip in zincate for 2 mins, rinse, flash nickel - part comes out fairly shiny, rinse then acid copper for 20 - 30 mins.

At this point my problem occurs. Blistering. The copper comes out quite shiny and sometimes with no blisters until a few hours later however, blisters are usually present straight away. On carefully scraping the blistered copper away the bare alloy is exposed.

I think the problem must be the zincate. Question is - after 2 mins in the zincate solution (75 degrees) the part appears still shiny but with a grey tint (sometimes very faint tint, sometimes dark). Is this right or should it be dull not shiny? Also, the manual states no more than 2 mins, why is 2 mins the limit?
Have also tried dipping part in sulphuric acid for 1 min prior to zincate which gives a darker tint but still blisters.

I also left the part for a couple of days after nickel flash and there is no blistering until I do acid copper.

Any help on this problem would be much appreciated. Thanks in advance.

QuentinV

[KCV6]

If the zincate solution is very new, I would leave the item no longer than 15 seconds. Is the item fizzing at all? If there is no fizzing and the item is still very polished after zincating I would suspect the item is not fully de-greased. What de-greaser are you using in the ultrasonic tank? Hydrocarbon or general alkaline degreaser? Zincate normally dulls the polished finish.

The 2 minutes normally applies to weaker solution that has been used without re-charge.

From my experience, too much zincate will cause blistering as a thin layer is left between the aluminium and the nickel or flash copper. The best result is when all the zincate is disolved as the plating layer first goes on.

I subscribe to the double zincate method with an intermediate 1% nitric etch between. Seems to work best for me. so after degreasing and rinsing I zincate for 10 seconds, etch off for 10 seconds or so in 0.5 to 1% nitric, then zincate for a further 10 to 15 seconds depending on the level of reaction (how violently it fizes) thorough warm water rinse then live into the flash copper.

Cheers... Mark

[quentinv]

Thanks for the reply Mark

The zincate solution is quite new and the item starts fizzing almost immediately BUT only the non-polished side which isnt going to be plated. The polished side dosn't seem to fizz even after 2-4 mins. Dipping an item for less than 30 secs does absolutely nothing.

I am using both Caswells SD416 and SD175 which I believe are the equivalent UK degreasers to SP.

Over here in the good old (cold) UK, nitric acid is not readily available. However, I have tried the double zincate method using battery acid and it does make a difference to how quick it turns grey but there is still blistering (sometimes).

Do you scrub your items at all because I think it makes a difference for me?
Do you dry your items before zincating them because that seems to also make a difference?

Anyway, meanwhile I will attempt to degrease the items more thougherly and let you know how I get on.

Cheers for the advice, much appreciated.

Quentin

[woodjames]

I've done a few parts from an '80 Kaw and this is what I've found. Purchase the de-smut/de-oxidizer from caswell. Also, it sounds like the part isn't clean enough. I have finally gotten to the point where I can solder on aluminum without blistering, but only from proper cleaning. Anything less and it's blister city. Instead of using the hot SP degreaser for Aluminum use hot dawn detergent. It takes forever! to clean, use brushes and sponges on it until it truly passes the water break test. Rinse off with warm running water, de-smut for 5 to 10 minutes (older alloys), rinse, then zincate. The benefit of the Dawn instead of the SP is that the part comes out shiny still after cleaning, and it's immediately evident when the grey color of the zincate is deposited. The SP degreaser etches a little too much, notice all the bubbling when aluminum is in the degreaser? And since it's coming out such a dark grey color even after polishing, it's hard to discern the zincate. I'm not bashing the SP at all, it works amazing on ferrous and copper/brass, especially because there is barely any scrubbing necessary. The dawn works, but really takes a while, and you want to use it just as hot 180 F or so. You may also want to try a low pressure glass bead blast after polishing, I've had this help also. After a quick bead blast you will notice the zincate fizzes and bubbles much much more. I know you are using an ultrasonic cleaner, but you didn't mention about the water break test nor did you say how long you have it in the nickel for. If properly cleaned without etching the aluminum too much, such as the Dawn method, it should come out of the nickel shiny. Also, with as easy as it is to remove the defective spots from aluminum, why are you dropping it in the acid copper? Because it's dull from the flash nickel coat? Clean and rinse well between all steps, zincate's not too bad, even on the zinc'd up aluminum from the old bikes. It helps to scrub the piece after the nickel to assist with the copper sticking to it. Also, if you think it's blistering bad from the copper, wait till you see what the chrome will do to it with the higher amps!!! Has anyone tried the new room temp degreaser on aluminum yet

Hi

Got a couple of questions concerning the dreaded zincate process.

I am attempting to triple chrome plate aluminum alloy parts from a 1980's Japanese motorcycle. Using all Caswell products my process is as follows:
1. Degrease highly polished part in ultrasonic bath for about 15 mins. Scrub with nail brush.Rinse.
2. Dip in zincate for 2 mins, rinse, flash nickel - part comes out fairly shiny, rinse then acid copper for 20 - 30 mins.

At this point my problem occurs. Blistering. The copper comes out quite shiny and sometimes with no blisters until a few hours later however, blisters are usually present straight away. On carefully scraping the blistered copper away the bare alloy is exposed.

I think the problem must be the zincate. Question is - after 2 mins in the zincate solution (75 degrees) the part appears still shiny but with a grey tint (sometimes very faint tint, sometimes dark). Is this right or should it be dull not shiny? Also, the manual states no more than 2 mins, why is 2 mins the limit?
Have also tried dipping part in sulphuric acid for 1 min prior to zincate which gives a darker tint but still blisters.

I also left the part for a couple of days after nickel flash and there is no blistering until I do acid copper.

Any help on this problem would be much appreciated. Thanks in advance.

QuentinV

[quentinv]

Thanks for the reply woodjames.

I have been thinking about the de-smut/de-oxidizer but hoped to avoid it especially as I'm skint at the moment! I will phone Caswell tomorrow and ask
about it.

I've never heard of hot dawn detergent, not sure if it's available in the UK but will look into it.

The items always pass the water break test, it doesnt seem to take much cleaning to get to that point.
I flash nickel the item for 10 or 15 mins and it comes out quite shiny but no way as shiny as with a polished acid copper base, hence having to add the copper. When I plate steel the nickel is very shiny just after a few minutes.

Thanks for the help.

Quentin

[woodjames]

Sorry, forgot about you being in the UK, hot dawn detergent...Dawn is a dish washing detergent brand, especially good at cutting grease. Hot as in temperature, but sure to protect your hands when scrubbing 'cause it's easy to get burned. Sorry 'bout that.

-Jimmy