Finishing – Brush, rattlecan or airbrush?

[AjohnwParticipant @ajohnw51620]

There are some model engineer type instructions here Jim

**LINK**

also this one

**LINK**

Personally from painting things I would degrease using other things and then wipe over with thinners and if it was aluminium or brass provide a key with a scratch brush as well. As far as I am concerned it takes a lot of solvent to remove all traces of grease. If not some will be left behind when it evaporates but that's based on cleaning things where any residue left is far more apparent than it would be on metals.

John

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[JasonBModerator @jasonb]

Jim, look at the link I posted at the start of this thread as to how I prep a casting set.

[JAParticipant @ja]

I have had a look at my work diary for my Stuart engine. The final cleaning was with methylated spirits followed by white spirit (British terminology). Ten coats of paint were applied, one a day.

I have just machined a 9" cast iron flywheel and noticed that something dirty was coming out of the casting at the areas where the risers and headers had been, local porosity. I guess that this could spoil the finish when painted and think that the flywheel may have to be soaked in white spirit and/or thinners as part of the final cleaning. Comments, please.

JA

[Stuart BridgerParticipant @stuartbridger82290]

Nice to see how this thread has developed, it has answered all my questions. I have also treated myself to an airbrush for Christmas, now have to learn a new skill. Thanks to all who have contributed.

Edited By Stuart Bridger on 23/12/2015 10:43:39

[Ian S CParticipant @iansc]

Welcome to spray painting Stuart, I find it good fun, well all except the amount of thinners, first for cleaning the job, then after cleaning the gun, but the finish of the paint job makes it all worth while. It does take practice.

Ian S C

[AjohnwParticipant @ajohnw51620]

Solvents are sort of interesting. Some these days for paint are marked for professional use only – extraction needed. The health people seem to think we can buy as much IPA as we like – not the beer. it's pretty readily available. Ebay for larger amounts. I've only used it to clean optical glass some a fairly large sizes. It seems to work a lot more effectively as 30% mix with distilled water plus a drop of wetting agent. I've used all sorts of things for this and it's pretty clear at this level that vast amounts can be needed to remove all signs of grease / oil / finger marks etc. Fortunately micro fibre cloths will remove the last traces for this sort of thing.

I'd guess industry use some variant of this for degreasing metals now.

**LINK**

They used to use tric. – the baths were more like swimming pools. Highly addictive too given long exposure to the fumes despite attempts to minimise them.

John

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[Stuart BridgerParticipant @stuartbridger82290]

From memory of my time in the aircraft industry, it was mostly vapour phase degreasers followed by a boil in a mild caustic soda solution. Another memory from my apprenticeship days, I did a stint in the labs on a project researching surface treatment for bonding Titanium. No vapour phase plant in the lab, so it was raw tric on a rag to degrease the test samples before going into the "magic" solution we were testing . I forgot to open the window one morning and soon got very dizzy with a banging head. Those were the days.

[AjohnwParticipant @ajohnw51620]

I probably mentioned in part IPA as I have just had a degreasing experience. An off topic one. My Xmas present, a used Meade 8" F10 SC telescope. As it can take a while to test under clear skies I use terrestrial objects and crazy magnifications. When I tried it I was a touch disappointed. Ok but hoped for better. I then did a torch test on the glass and mirror and thought oh dear so stripped it and cleaned it all. Initially with the usual window cleaner that comes in spray bottles. It's basically the same mix of IPA I mentioned. Then a wipe with IPA followed by the microfibre cloth. I tested it again this morning. Whoopee. It now focuses cleanly and crisply with a 3mm eyepiece in it. Very very slight signs of miss alignment but that's probably because the telescope is horizontal.

Anyway if some one wants to try an IPA mix window cleaner is readily available and cheap. The wetting agent is needed so that the water in it doesn't bead and allows it to dry more quickly and evenly.

John

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[Dave Powell 2Participant @davepowell2]

One thing you may find useful is to buy a few syringes – they are graduated in ml's. Once you have found your favourite paint to thinners ratio it is then very easy to repeat it accurately.

[duncan webster 1Participant @duncanwebster1]

If it will fit, I find a good way to degrease is to put it in the dishwasher. The fluid is wicked stuff and gets rid of any oil or grease completely. If you've got steel bits, when it gets to the drying cycle take them out and dry them with a clean towel or you will get a slight rust coating.

If it won't fit then wash off with white spirit, then hot water with detergent, then rinse thoroughly with hot water, as hot as you can stand as it will then dry off quickly. Only using solvents just dilutes the oil, detergents and castic soda destroy it, and remove te residue left by the white spirit.

[AjohnwParticipant @ajohnw51620]

Posted by duncan webster on 23/12/2015 22:59:06:

If it will fit, I find a good way to degrease is to put it in the dishwasher. The fluid is wicked stuff and gets rid of any oil or grease completely. If you've got steel bits, when it gets to the drying cycle take them out and dry them with a clean towel or you will get a slight rust coating.

If it won't fit then wash off with white spirit, then hot water with detergent, then rinse thoroughly with hot water, as hot as you can stand as it will then dry off quickly. Only using solvents just dilutes the oil, detergents and castic soda destroy it, and remove te residue left by the white spirit.

I always wonder why people don't realise that some must be left when cleaning with solvents unless loads are used or there was next to none there in the first place.

If you can get hold of it there is a laboratory cleaner called teepol L. It's wonderful stuff for cleaning carburettor jets and should remove all traces of oil and grease.

**LINK**

I used to be able to "borrow" this when needed. Last time I looked there wasn't an easy on line source and my little bottle is empty. Looks like there is a source now, their on line shop.

John

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