Bleedout problem from pits in anodized fishing reels

A. Hi Tom. I'm surprised that the problem is less severe with black anodizing.

I think there isn't much you can do about pre-existing pits, but you may be able to do something about the bleedout of the sulfuric acid from them. Ask your anodizer to try these three ideas:

• 1) neutralizing the anodizing solution with sodium bicarbonate;
• 2) displacing the anodizing solution by a dip in dilute nitric acid;
• 3) hot & cold rinsing after the anodizing.

The three ideas can be combined, i.e., rinse hot & cold; dip in nitric acid; rinse; dip in sodium bicarbonate; rinse.

A. 1st: you already know - "better rinsing" then rinsing with air agitation. Then a hose nozzle that mixes compressed air with water, then a 5% Nitric Acid Dip between the anodize and the dye.

Sulfuric Acid is called "Oil of Vitriol" in the High School Chemistry Book because it is "oily" and difficult to rinse. Nitric is easy to rinse and will get down into the crevices and holes and help flush out the oily sulfuric.

In the case of extreme deep holes or spot weldments it is best to avoid all alkali cleaning and alkali etching. Use the phosphoric/detergent type of product to clean and stay out of all alkalies - then at least you will not precipitate a "salt" in the deep down places.

A. We try to Solve our bleed out problems by a number of ways and all depend on configuration of part:

1. Align part accordingly
2. Extra rinsing
3. Masking
4. Plugging blind holes (sometimes removing plugs before and rinsing with clean / fresh water will help)

A. You might try either introducing some really vigorous air agitation into one of the post anodize rinses, or using some kind of mild chelating agent into one of the post rinses.

Off hand, the white sounds like precipitated aluminium hydroxide from the anodizing electrolyte. Such problems are very common in work that is received assembled.

A. You also might try a sodium bicarbonate rinse for black you might have to re-rinse in sulfuric but it seems to help us on problem parts

A. Our facility anodizes complex assemblies every day and we have reduced our bleedout by 98% with the use of a proprietary additive in the sealing and final rinse stages of our process..

A. I realize the investment would be substantial, back when I was doing job shop work, I always wondered if ultrasonic rinsing would alleviate bleed out problems. I never got the chance to test it, but it would seem to me to be a possible solution.

A. Try alternate hot and cold rinsing before the anodize step. Hopefully it will pump the trapped fluid left from the preparation steps.

A. Rich

1] It may common for the dye to come off depending on your suppliers.

2] The seal probably has nothing to do with the 'dye' coming off on your/their hands. Organic dyes are water soluble and any excess would rinse off in rinses subsequent to the dye. The term bleed-out refers to areas with inadequate dyeing as a result of acid bleed-out removing the dye from the anodize. If 'black' is rubbing off, it is probably (softer) anodize.

If your supplier can not correct the problem, I would look for another.

A. This really can be boiled down to two basic possibilities:
1- the customer has not noticed it before .
2- the supplier of the anodize is doing something different.

First YOU must check the parts BEFORE they are sent to your customer to confirm that there are no problems with the dye. If you find a problem then it is time to look into how the anodize has been done! Several different things could cause this problem from soft anodizing to lack of a good seal. First try to touch the part after is is wet ,if it feels sticky to you finger than sealing is a problem.Also make sure there is enough anodize to hold the dye by checking thickness .5 to .7 is a common thickness that should work. Others may have other thoughts.

A. Hi Zach. Unfortunately, you're probably not going to be completely successful as a middleman soliciting help from the web to tell your anodizing shop what they should do to fix these problems; your best path might be simply to reject the parts as unsatisfactory. But we do have hundreds of threads about such problems if you're seeking general education.

This thread addresses your third question of bleedout, and you can search the site with the term "anodize bleedout" for additional threads.

The purple streaks in the first picture might by caused by bleedout, but another perhaps less likely possibility is that the parts might be racked/jigged from the center holes, and the racking might be 'stealing/shading' anodizing current from the streaked areas causing too thin anodizing. This is why it's hard to be in the middle, neither of us probably knows anything about the racking. A thickness tester might yield a clue.

The pitting issue is probably the toughest one to solve as it has many potential causes even including very old alloy of compositions that segregate over time. Do you know what alloy your parts are?

Finally, the first picture seems to have some 'white spots' which are not quite the same issue as the dark pits in the second picture. For that problem, please see Robert Probert's article on White Spots in our on-line library. Good luck.

Regards,

A. Hi Zach. Get some fine pumice ⇦this on eBay or Amazon [affil links] or even Bon Ami ⇦this on eBay or Amazon [affil links] , an old style tampico scrub brush ⇦this on eBay or Amazon [affil links] , a dollop of dish detergent and warm water. Pre-scrub and thoroughly rinse a few marked parts before inspecting them for pits with a jeweler's loupe, and sending them on to anodizing; this will remove all traces of machine coolant and it's interaction with the process, and you'll know that there were no pits when the anodizing shop's process started. From there you can move on to whether the problem is material vs. process.

Luck & Regards,