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Painting glow engine blocks?

Cleaning up that discoloured aluminium

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Nigel R12/08/2020 09:06:22
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4256 forum posts
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Hi all

Perhaps someone has done this before.

I have several engines (some old style Irvine 46s and OS 46 SFs) I am tidying up as a bit of a background project. One or two of them have discoloured aluminium.

Has anyone used any paint, successfully, on engine blocks?

I did think initially of the usual automotive answer, Hammerite, but is it resistant to glow fuel?

Thanks!

Dale Bradly12/08/2020 09:46:32
43 forum posts
13 photos

How timely you asked!

I have no idea, but am about to find out.

Recently gave me old Sig Somethin' Extra an overhaul, which included giving the OS 46FX a coat of gloss black powdercoat.

The powdercoater reckoned it will do it no harm, and possibly help shed some heat better than plain aluminium. Plenty of fullsize, and Saito engines, have it done. It looks the part, and owes me nothing if it doesn't work. And i got it done for free (on the proviso i report back to him on how it worked!)

First engine run, and first re-test flight as early as this coming weekend, I'll report back when done.

20200812_203912_richtone(hdr).jpg

Engine Doctor12/08/2020 10:08:29
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If you have access to spray equipment then automotive 2K paint baked on works well . I have painted a few over the years and all have lasted well. Rustoleum Hard Hat Paint in aerosols is also highly resistant to glow fuel if baked on. The discoloured cases can be reinstated to virtually AsNew by bead blasting ,now my preferred method. Any painted parts will need thorough clean degreasing to key properly to the alloy.

Vapour blasting using soda and water also produces an excellent finish but is costly as equipment is far it's expensive than bead blasting .

Some older OS engines were painted silver from new possibly to protect the alloy from discolouring. The LA engines were also painted but don't know what paint they used. All the LA engines I have done recently have been bead blasted and look great au-natural alloy.

Ps the powder coat above looks good . And looks like nice light coat.

Edited By Engine Doctor on 12/08/2020 10:10:20

Doc Marten12/08/2020 10:28:23
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981 forum posts
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It's possible to anodise aluminium at home but it means handling acids, boiling water and 12v supplies if you are willing to make that decision and confident in your abilities.

Cue the outrage from the safety police.

Denis Watkins12/08/2020 10:44:17
4654 forum posts
132 photos
Posted by Doc Marten on 12/08/2020 10:28:23:

It's possible to anodise aluminium at home but it means handling acids, boiling water and 12v supplies if you are willing to make that decision and confident in your abilities.

Cue the outrage from the safety police.

Talk about safety police, in my teens the local steel storage firm would do some motor bits for me free.

The parts were wired onto hooks and dipped into an open heated vat of carbontetrachloride to decrease them

They were then sprayed with stoving enamel and went through an hot air oven.

Most certainly fuel proof to this day, and the forerunner of modern 2K

Edited By Denis Watkins on 12/08/2020 10:45:03

Jon - Laser Engines12/08/2020 11:01:12
5665 forum posts
272 photos

I used some engine enamel from amazon on my ASP400 radial rebuild. It didnt come off immediately so i call it a win.

Im not buying the line from the powder coat guy though. Any coating on top of the aluminium will act as an insulator, but i really doubt it will be enough to do any harm. 

Edited By Jon - Laser Engines on 12/08/2020 11:03:07

Nigel R12/08/2020 11:39:24
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4256 forum posts
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Thanks for replies, chaps, paint types noted.

Posted by Engine Doctor on 12/08/2020 10:08:29:

If you have access to spray equipment then automotive 2K paint baked on works well . I have painted a few over the years and all have lasted well. Rustoleum Hard Hat Paint in aerosols is also highly resistant to glow fuel if baked on. The discoloured cases can be reinstated to virtually AsNew by bead blasting ,now my preferred method. Any painted parts will need thorough clean degreasing to key properly to the alloy.

That's interesting. I wasn't aware a bead blast would remove some (if not all) of the discolouration. Perhaps a bead blast might be the easy answer... Will a bead blast also take off an anodised layer?

As ever, pictures, thousand words...

First the SF. The staining is not too bad. The prop driver has unwanted anodising, although not a deal breaker as I have another engine with a clean driver.

20200812_112639.jpg

The worst bits:

20200812_112656.jpg

20200812_112708.jpg

And one of the Irvines (the other is far cleaner):

20200812_113016.jpg

20200812_113058.jpg

Barrie Lever12/08/2020 11:59:39
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392 forum posts
55 photos
Posted by Doc Marten on 12/08/2020 10:28:23:

It's possible to anodise aluminium at home but it means handling acids, boiling water and 12v supplies if you are willing to make that decision and confident in your abilities.

Cue the outrage from the safety police.

Doc

Nothing wrong with a bit of home anodising, don't know what the worry is !! smiley

Do it all the time on small parts, gets a bit more tricky on something like a crankcase as the current has to be quite a bit higher and also the acid gets hot.

A couple of engine mounts for the pulse jet below, the flag is laser engraved after anodising.

B.

dsc_1175.jpg

Doc Marten12/08/2020 12:53:56
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981 forum posts
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That sounds like a future new forum topic for those of us interested in widening our skillbase Barrie. wink

jeff2wings12/08/2020 17:23:08
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836 forum posts
2044 photos

Maybe Nigel you should take a look at some of my engine threads to see what can be done with old 'dead' engines

Engine Doctor12/08/2020 19:08:56
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2659 forum posts
40 photos
Posted by Doc Marten on 12/08/2020 10:28:23:

It's possible to anodise aluminium at home but it means handling acids, boiling water and 12v supplies if you are willing to make that decision and confident in your abilities.

Cue the outrage from the safety police.

Hi Doc . crank cases don,t like being anodised as they are an alloy contianing all sorts and not pure aluminium.

Nigel . the dark corrosion marks may show up after bead blasting as small dips in the surface

Heres a before and after of bead blasting

BEFORE.

124_2375.jpg

After124_2382.jpg

As you can see the finish is almost as new . Good luck with whatever finish you decide on .

E.D.

Doc Marten12/08/2020 21:04:56
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981 forum posts
19 photos

Thank's for the clarification ED, what blasting media do you use?

Barrie Lever12/08/2020 23:18:52
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392 forum posts
55 photos

E.D

Nice work on that Saito, is that done in a domestic (Machine Mart/Seally type) or an industrial unit?

B.

Engine Doctor13/08/2020 09:22:22
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2659 forum posts
40 photos

Hi Doc . Blast media is glass beads. Don't use crushed glass as it will leave surface like a fine file ! Soda crystals work OK but absorb moisture then set in a lump and need regular breaking before use. I have tried some different media but medium glass beads are best for me. They do wear out and need replacing now and again . Cost of refill is about £20 but have to buy bigger bag to get a reasonable price.

Hi Barrie. It's a home unit with mods. Most important mod is the use of a cyclonic dust extractor . A small vacuum cleaner maintains a negative pressure inside cabinet that stops workshop getting smothered in dust and the cyclonic filter catches the dust before it reaches the vacuum cleaner. Other mods are a new thicker perspex top with better hinges and better rubber seal.

It's a smaller unit approx 30 inch cube . It still needs lots of air so a big compressor is needed if you want continuous blast capability.

Unit cost me £70 ish on eBay ,think they are about £100 ish now. Cyclonic filter is home made cost about £10 excellent bit of kit.

If you are thinking about going down this route be aware it is time consuming and preparation before blasting is key to success.

E.D

Nigel R14/08/2020 11:23:11
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4256 forum posts
711 photos

ED

that OS looks brilliant.

I suspect getting into bead blasting is a rabbit hole I can't afford to go down...

jeff2wings

I have seen some of your merco photos, they do look great after some TLC.

Dale Bradly23/08/2020 08:04:01
43 forum posts
13 photos

My black OS46FX above runs like a sewing machine, and had 4 excellent flights today with no problems at all. The motor turned heads at the club. (not just because of the colour, it was also the only IC powered model thats flown there for some time i think).

Most happy with the result.

Engine Doctor23/08/2020 10:32:39
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2659 forum posts
40 photos

Keep flying the IC flag yes. Our club is the same with very few IC models these days. Did the powder coat hold up ok ?

Dale Bradly23/08/2020 11:43:53
43 forum posts
13 photos

Like a bought one

Steven Webb (Steve Webb Models)10/09/2020 15:49:40
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302 forum posts
103 photos

I just read through this thread and I’ve been messing with heat proof paint that is made for painting automotive brakes. I’ve managed to get Signal Red , Green and Matt Black and Satin Black. Another modeller pal put me onto them as he had used them to re paint the black on Mills magnesium cases and ED Racers . Some Marine Diesels also,

I have used the paint on a few engines but I’ve not run any I’ve painted ( yet).

I have in the last 18 months invested in an ‘industrial ultrasonic cleaning bath’. The first time I painted Diesel engine the coating of the Red painting , the paint lifted easily . I found that cleaning the engine with an additive that’s designed for cleaning car and motor bike carbs worked a treat at degreasing the engines ready for the brake paint . I’m fairly confident the paint will stand diesel fuel . Not sure about glow fuel.

The ultrasonic cleaner with the carb cleaning additive makes a great cleaner / degreaser . It would work well for pre anodising treatment . It’s something else ( anodising ) I have been reading up on .

I found an interesting video about anodising . I’ll try and find it and post back

interesting thread

Steve

Engine Doctor25/09/2020 12:19:25
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2659 forum posts
40 photos

 

That's interesting. I wasn't aware a bead blast would remove some (if not all) of the discolouration. Perhaps a bead blast might be the easy answer... Will a bead blast also take off an anodised layer?

As ever, pictures, thousand words...

First the SF. The staining is not too bad. The prop driver has unwanted anodising, although not a deal breaker as I have another engine with a clean driver.

20200812_112639.jpg

The worst bits:

20200812_112656.jpg

20200812_112708.jpg

And one of the Irvines (the other is far cleaner):

20200812_113016.jpg

20200812_113058.jpg

Sorry for late reply . The anodising is best removed by dipping the part in a solution of caustic soda then a good rinse / wash in water . It will leave part a matt finish and will need re-polishing/finishing..

Bead blasting will restore all the markings on the casings to an original finish although the sides of the cylinder head are a tuned bright finish and will need spinning in a lathe if you want the original or near to original finish

Re Bead blasting . Make sure that Glass Beads are used and not the cheaper crushed glass . Crushed glass produces a coarser finish that is ideal for getting good paint adhesion but slightly feels rough to the touch and seems to grab dirt making cleaning difficult.

 

Edited By Engine Doctor on 25/09/2020 12:20:05

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