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Aluminium boat de-oxidising

Printed From: The Fishing Website
Category: Saltwater Fishing
Forum Name: Hints,Tips and How To's
Forum Description: Rigs, tackle, baits, angling techniques, tips and hints & your DIY projects here
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=126190
Printed Date: 23 Aug 2019 at 6:45pm


Topic: Aluminium boat de-oxidising
Posted By: Big_Red
Subject: Aluminium boat de-oxidising
Date Posted: 11 Nov 2017 at 7:32pm
Hi fellas,
Time to look at either an upgrade or birthday for my stabi 430. It’s in bloody good Nic but suffers from the normal oxidation most alloy boats do.

Does anyone have first hand experience (not opinion) with any of the spray on deoxidising agents such as Star Brite, CRC (Mary Kate’s I think it’s called) and the likes?

I’ve watched just about every video on YouTube and the seem quite convincing, almost too convincing.



Replies:
Posted By: pjc
Date Posted: 11 Nov 2017 at 8:40pm
I wouldn't use anything that is going to polish it but use something that remove the excess,but remember the oxidization is part of the protective process for ally

Wonder why ali boats are not anodized,sheer size I guess.


-------------
water water everywhere,how many fish does it hold?


Posted By: Big_Red
Date Posted: 11 Nov 2017 at 10:06pm
Yes it’s odd, mines oxidised but also has tiny white spots on it. Nothing drastic, just could be tidier.
I have subsequently found a massive thread on the subject in another part of the forum. Makes for interesting reading.


Posted By: Steps
Date Posted: 12 Nov 2017 at 11:52am
Alloy oxides, like galv, forming an oxide layer of very hard and tightly packed molecules...basically a seal preventing further corrosion.
 Unlike iron/ steel rust that the oxide is not hard, , rather flakey..
 If alloy is HIGHLY polished, like chrome, it will resist for very long periods oxidation. As there are no imperfections.. or at lease very little, there are very few points at which oxidisation will start.
 Which is why hot rodders alloy tappet covers/ alloy wheels remain shiney so long.
 BUT if the surface comes in contact with things like silicones, it will start to oxides.

If wish to 'polish' up theboat, the easiest and simplest is to wash down VERY well.... then use a strong soln of  citric acid or vinegar.. keeping the area wet for several hrs (depending on the depth of oxidation)
 Wash off.. you have straight alloy surface.
 Now with a cloth buff, using ( I prefer fine grade stainless steel rouge) and kero start buffing.

 When polishing aluminium, its different to other metals.
 You generate a lot of heat in the area being polished.. this 'melts' the top molecular layers of the alloys and fills in the scratches, imperfections.
 Its is a very messy dirty job, but will cover large areas quicker than expect.
 You may like to finish with a final light buff with a  orange sponge disk and very fine car cutting compound.
 To maintain the finish, Wax polish with a high grade car polish.. 3 polishes.. each 1 week apart to build up good seal meguires/ mothers.. only use their car wash products, as they need to be compatible with the polish so as not clean it off after washing ....

 Thats how to do it properly for best shine and lasting.
 Sort cut anything and nothing will last for long.
 And being a boat, not a hot rod alloy rim or tappet covers/ car trim.. will not last anywhere as long as those.

 Personally, a good wash, a vinegar or citric acid wet soak wash...and a quick buff then polish will do wonders for appearance..anything more for keeping long term results will be lot effort for disappointing long term.




Posted By: Durban
Date Posted: 24 Feb 2018 at 6:45pm
There is only one way to pasivate aluminuim and the correct way is not mentioned here or on youtube.


Posted By: The Tamure Kid
Date Posted: 24 Feb 2018 at 8:00pm
Care to enlighten us tinny owners?


Posted By: Durban
Date Posted: 24 Feb 2018 at 9:16pm
Aluminium [ from Wikipeadia ]

Pure aluminium naturally forms a thin surface layer of aluminium oxide on contact with oxygen in the atmosphere through a process called oxidation, which creates a physical barrier to corrosion or further oxidation in many environments. Some aluminium alloys, however, do not form the oxide layer well, and thus are not protected against corrosion. There are methods to enhance the formation of the oxide layer for certain alloys. For example, prior to storing hydrogen peroxide in an aluminium container, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxide alternating with deionized water. The nitric acid and peroxide oxidizes and dissolves any impurities on the inner surface of the container, and the deionized water rinses away the acid and oxidized impurities.[9]

Generally, there are two main ways to passivate aluminum alloys (not counting plating, painting, and other barrier coatings): chromate conversion coating and anodizing. Alclading, which metallurgically bonds thin layers of pure aluminium or alloy to different base aluminium alloy, is not strictly passivation of the base alloy. However, the aluminum layer clad on is designed to spontaneously develop the oxide layer and thus protect the base alloy.

Chromate conversion coating converts the surface aluminum to an aluminum chromate coating in the range of 0.00001-0.00004 inches in thickness. Aluminum chromate conversion coatings are amorphous in structure with a gel-like composition hydrated with water.[10] Chromate conversion is a common way of passivating not only aluminum, but also zinc, cadmium, copper, silver, magnesium, and tin alloys.

Anodizing is an electrolytic process that forms a thicker oxide layer. The anodic coating consists of hydrated aluminum oxide and is considered resistant to corrosion and abrasion.[11] This finish is more robust than the other processes and also provides electrical insulation, which the other two processes may not.


Posted By: The Tamure Kid
Date Posted: 24 Feb 2018 at 9:45pm
Another reminder why I barely passed chemistry and physics at school. Thanks for following up.



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