Anodising engine parts at home.

[Engine Doctor]

Some of yoh have expressed an interest in anodising aluminium parts you have made or re-anodise old parts. This thread is by no means a definitive "how to" but jut a run through of how I do it and some of the pit falls that can happen. 

You may also want to look on YouTube as there are quite a few  vids onthere re anodising at home. Some are good solid advice giving vids others are .....well sort of pie in the sky rubbish. Have a look through and you will spot the wheat from the chaff.

 

Some alloys won't anodised very well as they will contain various other metals that prevent the process from working .

Anodising is a way of creating a layer of oxidation on the aluminium  or aluminum for our US friends ;by the way both names are correct as it has been changed a couple of times by the maker/dicoverer.

Most of the 6000 grades of alloy will anodised but some better than others. Really cheap alloys and die cast / pot metals won't anodised.

 

To start anodising you will need the following hardware:

A plastic or non metalic tank big enough to hold items to be anodised .

Four glass or plastic rinse tubs.

Some aluminium wire or titanium wire to suspend parts to be anodised.

A power source battery charger or similar

Some lead or ali strip

 Electrolyte  caustic soda solution

A good supply of distilled or de-mineralised water

If you want consistent results some de-smut acid dip.

 

There is some discussion re what electrolyte is best. Some folk suggest using sodium metabi-sulphate or pool Ph adjuster. Phosphoric acid or sulphuric acid H2So4 I've found that sulphuric acid works best and battery strenght diluted 50/50 with distilled water gives reas9nably consistent results. I've bought some phosphoric acid to try as Sulphuric acid is now very hard to come by . 

Warning : when diluting any acid always add acid to water NEVER add water to acid 

 

So once your parts are made and polished they need to be cleaned . By cleaned I mean REALLY clean and have the oxide , that forms almost instantly has t be removed before going into the bath. More soon. 

 

[Engine Doctor]

Before I forget add some dye of choice to the list above ., and a jar of Bicarbonate of Soda just in case of accidents .

Make sure the room or area is well ventilated as it gets quite fumy.

 

A couple of decent site to get the idea of the process are 

ebd Guide to Anodising: Anodizing Explained How To Anodise aluminium part at home (engineeredbydesign.co.uk) 

How to Anodize Aluminum (with Pictures) - wikiHow

Anodizing for the DIY crowd (bryanpryor.com)

 

These site will show how to set up  your tank . Now you need a rinse container of distilled water, a container of caustic soda solution and a container of Desmut solution I also have a container of tap water handy and the jar of Bi-carbonate of Soda .

 

So you have your part polished, see pic below . This has been polished on a buffing wheel to a near chrome like finish but will still have a layer of oxide that needs to be removed before anodising, Now put on a pair of rubber gloves as your finger prints will stop anodising from working. Don't forget anodising doesn't cover any blemishes . If there is a scratch it will end up as a an anodised scratch. Give the part a really good scrub in a de-greaser with a tooth brush and rinse in some HOT water . Repeat a couple of times until water doesn't bead on the item.  Now fit it to a piece of the aluminium or titanium wire and hang it in the caustic soda for a couple of minutes . Remove and rinse in distilled water. Now dip into the desmut solution for a minute or so . This dissolves any metals other than aluminium on the cleaned surface. Rinse and then hang in the anodising bath making sure it doesn't touch the Lead or Aluminium anodes . Remember Nothing but Aluminium , Lead or Titanium in the bath. 

Connect the negative - to the anodes and The positive to the item or cathode and switch on the charger or power supply. For a couple of cylinder heads etc I set it at 12 -15 volts at between 0.5 and 0.75 amps . The anodess should start to bubble quite freely and a few bubbles will be seen coming from the cathode or item . Now leave it for an hour. While its cooking prepare your dye . This is best used warm as it helps it to soak into the pours created by the anodising process . Remember  just warm but not hot,

If Item has previously been anodised this  can be removed by a soak in the caustic soda bath but beware it will reduce or eat away any bearing surfaces .

some more a bit later 

Edited February 10, 2023 by Engine Doctor

[Engine Doctor]

OK so your part has been anodising for an hour in the acid bath. The items if anodised sucessfully should have a  slightly milky appearance when removed from the bath . Now rinse in distilled water and dip into your chosen dye. This should be slightly warm . Too warm and it will start to close the pores in the oxide and prevent the uptake of the dye

While it's soaking get an old saucepan with some distilled water on the boil.

Many things can be used as a dye , from the expensive purpose made dyes to printer inks , clothes dyes (Rit ) to writing ink.  Dylon  used to work well but has now changed formula and doesn't appear to work very well. The primary colours apart from yellow work with most dyes but colours vary a lot so a bit of experimenting is needed. 

Red printer ink produces a very rich pink colour so if a deep proper redis wanted the I found Rit dark red is best. A short soak with Rit dark red will produc a red very similar to  Davies Charlton red. Leave it a bit longer and a beautiful deep Ruby red form.  I can't emphasise enough that if you want to repeat a specific colou/shade then you really need to experiment with A, type of ali , B time in anodising bath.C,dye used. D temp of and time left in the dye.

Also secondary colours like green can be difficult to get to take properly. For instance mixing a nice green from blue and yellow dyes or even using a premixed green dye can result in a beautiful green deposit in the item but when you set ( close the pores) the yellow tends to wash out into the hot sealing bath and leaves a light blue colour with a green tint ! Very frustrating. 

 

Dip the part for a few seconds and check to see if dye is taking ok. If it is then the longer you leave it to soak the darker colour you will get. The Frog 150 head was left in the dye for around 20 mins. Different dyes will work at different speeds .For lighter colour just keep checking and remove when happy with colour. Tip, some of the colour will wash out when it's put into the hot sealing bath so let it go slightly darker than your chosen finished shade.

When happy remove and place into the pan of hot distilled water and boil for 20 to 30 mins. This closes the pores formed in the oxide layer and seals in the dye .Once sealed allow to cool in the water then remove and polish with dry cloth . Now place in a plastic bag and squirt some wd40 or thin oil and l3ave overnight. The result is worth the wait. You can remove from sealing pan when hot but polish as quickly as possible as a whitish film dries on and  can be a so and so to remove.

 

If you get a bit more interested them other tools like a magnetic stirrer can be used to stir the anodising bath . This stops burn marks that can sometimes occur that can ruin a nice finish. 

 

It can be a minefield but it very rewarding when it turns out well

 

I'll add some pics of stuff later when the bench is clear.

Edited February 11, 2023 by Engine Doctor

[Engine Doctor]

Below are some pics of the polished parts from a Magnum 10  diesel conversion I made . They need polishing to a high degree or all machining marks will be seen and exaggerated.

 Next pic is the finished  Magnum 10 conversion . This was supposed to be emerald green . the dye was made by mixing a blue and yellow Rit dyes . You can see what I mean by all the yellow washing out while sealing the pores in the oxide . I left this as it does look quite attractive  and would be a lot of effort to change it .

The next pic is a OS 15 . This again was supposed to be a emerald green and was when it came out of the dye bath but again the yellow washed out leaving a rathe nice ultramarine blue so I left it . This used a pre made emerald green dye but obviously made the same way as i made the previous dye .

 

Th last pic is a nice dark red cylinder on a Magnum 40 conversion. The dye used was Rit Bordeaux  red . Lighter shades can be achieved with a shorter dip time .

 

I finally managed to get a nice green finish on the Boddo mills crankcase I made after the original split open and then started to melt when I was attempting to repair it ! The finished polished case is  pictured earlier in the thread. This colour was made  by use some proper anodising dye powder bought online . The stuff is almost as expensive than gold by weight ! Luckily Im only using very small amounts and it keeps .  

 

The dyes last well if kept in clean glass containers 

.Make sure to use nitrile or latex glove at all times when anodising as coloured hands get very strange looks 🙃but more importantly any finger print grease will ruin your anodising. 

 

The spinner nut on the Boddo Mills Is a good example of the way anodising  react differently to different alloys . This is an original nut supplied by CS with the engine and is obviously made from a rubbish alloy as the anodising started to fle the first tie the nut was done up. The case is made from 6024 alloy ...... I think from memory and machines and anodises nicely .

 

I will show some pics of the tanks I use but this will have to wait until the bench is clear .

 

Give it a go as its very satisfying and post any pics of finished items .

 

 

You may notice that some of the comp screws on the converted engines are nickel plated. If anyone is interested I can do a similar"how to"  post ,

Edited February 12, 2023 by Engine Doctor

[Lauriew58]

Thank you for taking the trouble to put all of this info together, it is much appreciated. As would be the nickel plating story. I'm really impressed with your results from the processes.

Laurie.

[jeff2wings]

Very informative ED,thanks for taking the time and effort posting your experience with this process, definitely will have a go at this