Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
-----
Want dip process for brightening bare aluminum
Q. Dear Sir/Madam,
We are a group manufacturing aluminium cookware in Kenya. We have a requirement for a brightening chemical for our finishing process.
Our products have a milky white finish and we want to achieve a glossy/shiny silver finish but not like Stainless steel.
Please advise if anyone can advice on suitable chemicals.
We do not do or intend to do anodizing, hence the brightening will be the last and finishing process.
Thank you.
- Mombasa, Kenya
April 14, 2021
A. Hi cousin. I see two potential issues involved with your question. First, bare aluminum can resist corrosion in favorable environments but is unlikely to have much corrosion resistance and to stay bright for long in a corrosive environment. Be sure to pick an aluminum alloy well suited to your requirements; pure aluminum is perfect for this, but its other properties may not suit you.
The second issue is that aluminum usually requires mechanical polishing to achieve brightness, not just a dip.
I think readers could offer you much better guidance if you explained more fully what your product is. If it's general pots and pans for home kitchens, I think you'll find the need to mechanically polish and buff them; plus I don't think you can use an aggressive and poisonous aluminum bright dip as your final process, simply rinsing the poison off of a food surface.
I've never been involved in aluminum cookware though, and hopefully a more knowledgable reader will chime in.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 2021
Brightening of Aluminium Cookware without fumes
May 11, 2021Q. Dear All,
We are manufacturers of non-coated aluminium cookware for the African Market. Our products consist of cooking pots, frying pans, milk cans, kettles etc.
We use a mix of aluminum ingots and local scrap in our casting process.
For our cooking pots, we have a alkaline spray tunnel system to degrease them and clean them. However the alkaline etches the surface and leaves us with a dull milky white surface finish. Sometimes with black patches that indicate alloy inconsistencies or defects.
We want to achieve a more bright silvery semi-gloss finish. Chemical brightening processes may work for us; however, I need more guidance on the process and what chemicals to use. However, we want a non-electrolytic process ... most importantly chemicals that do not foam or give out fumes, or have suppressants.
What kind of elements affect the surface and how do we avoid them?
We have been consulting mainly firms in India as they have a similar market as ours in Africa.
I would be pleased if someone could guide us on how we can achieve the finish required.
Much appreciated. Thank you.
- Mombasa, Kenya
A. Hi Milind. I'm not aware of any chemical brightening process for aluminum that is both non-electrolytic and doesn't fume. Further, chemical processes react with the metal and will emphasize rather than minimize any inconsistencies or defects in the material. Why not mechanical polishing and buffing?
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2021
May 18, 2021
A. I really feel you are going to have problems solving this problem.
1- Using a caustic solution for cleaning is really a problem since it will dissolve and etch aluminum leaving a dull surface. So find a mild non etch cleaner to clean the parts.
2- Then use an acid de-smut to prepare the aluminum for anodizing.
3- the only way to get a bright finish is to hand polish the aluminum then mild clean and de smut the parts.
adv.
If you contact me I will email our anodizing the basics info. That is the best I can do
Drew Nosti, CEF
Anodize USA
Ladson, South Carolina
Q, A, or Comment on THIS thread -or- Start a NEW Thread