Cleaning before painting

[SillyOldDufferModerator @sillyoldduffer]

As always, the answer depends!

An oil-based paint, like wot comes in a Halford’s Can for touching up cars, is probably tolerant of oily residue left after partial cleaning.   But it won’t be tolerant of watery residue left after partial cleaning.   Conversely, a water-based paint won’t be too upset by watery residue, but it will be upset by an oily surface.

I guess Arcylic paints behave more like water-based paints than oil, but don’t know.  Nor do I know what the various drying agents do when contaminated.   If the behaviour is uncertain, or it matters, do a proper job.

The secret of perfect paintwork and glued joints is absolute cleanliness.   That said, if paint adheres without blemishing, and stays on for a few years, then, hurrah, that bodge clean was ‘good enough’.  Absolute cleanliness isn’t always essential.  Sad though, when a time consuming paint job bubbles, flakes, or rusts underneath after a year or two.

Also depends on what the paint is supposed to achieve.   I mostly paint to provide light interior corrosion protection and to cover up embarrassing cosmetic flaws.  That’s much less critical than a serious paint job, intended to protect against all weathers for decades, or to satisfy Inspector Meticulous at a Gold Medal competition.

Dave

[JasonBModerator @jasonb]

Halfords rattle cans aren’t oil based. The secret is to first know what you are dealing with 😉

[Dave WoottonParticipant @davewootton]

On the advice of a local paint shop that does all sorts of strange custom finishes on cars and bikes, and who let me use their beadblaster in exchange for occasionaly fixing their air compressors. I degrease things with Screwfix no nonsense cleaner, water based and diluted, warm if possible. This I was told does leave a residue which comes off with either brake cleaner or panel wipe. I have not had any problems with paint adhesion since even on some old machines that have been oily for 50 years or so. Use the same thing on models and while my painting would never win a prize, the paint does at least stay on now! I give a special going over and rinse with the brake cleaner or wipe where things like stays meet the frames as before I had trouble with the trapped oil leeching out and affecting the etch primer. If you ever want to get an extreme reaction wave a can of WD40 around in a paint shop, evidently it can cause dreadful problems with their paint finishes! Was rugby tackled from my hand in seconds.

[SillyOldDuffer]

On SillyOldDuffer Said:

As always, the answer depends!

An oil-based paint, like wot comes in a Halford’s Can for touching up cars, is probably tolerant of oily residue left after partial cleaning.   But it won’t be tolerant of watery residue left after partial cleaning.   Conversely, a water-based paint won’t be too upset by watery residue, but it will be upset by an oily surface.

I guess Arcylic paints behave more like water-based paints than oil, but don’t know.  Nor do I know what the various drying agents do when contaminated.   If the behaviour is uncertain, or it matters, do a proper job.

The secret of perfect paintwork and glued joints is absolute cleanliness.   That said, if paint adheres without blemishing, and stays on for a few years, then, hurrah, that bodge clean was ‘good enough’.  Absolute cleanliness isn’t always essential.  Sad though, when a time consuming paint job bubbles, flakes, or rusts underneath after a year or two.

Also depends on what the paint is supposed to achieve.   I mostly paint to provide light interior corrosion protection and to cover up embarrassing cosmetic flaws.  That’s much less critical than a serious paint job, intended to protect against all weathers for decades, or to satisfy Inspector Meticulous at a Gold Medal competition.

Dave

[Dave Wootton]

On Dave Wootton Said:

…. If you ever want to get an extreme reaction wave a can of WD40 around in a paint shop, evidently it can cause dreadful problems with their paint finishes! Was rugby tackled from my hand in seconds.

Or even worse, Mr Sheen polish 🙁

Rob

[duncan webster 1Participant @duncanwebster1]

<li style=”text-align: left;”>So I wiped it down thoroughly with IPA, then sprayed it with Halford rattle can grey primer. Looked lovely. Left 24 hours and set about the top coat. Whilst shaking the can vigorously for 2 minutes I managed to drop it, the spray nozzle broke off, so back to Halford today for a new can, £12 worse off. Ah well, worse things happen at sea.

[duncan webster 1Participant @duncanwebster1]

So here it is in all it’s glory

[Neil Wyatt]

On Neil Wyatt Said:

aluminium

On Oldiron Said:

Why does the spell checker tell me I have spelt ALUMINIUM incorrectly ?   Have we gone all American now.

Spell checker will be the one in your browser, so it’s your local settings (FWIW mine is set to UK English).

There is no longer one built into the forum editor as a browser based one means it’s consistent across all websites.

Sorry for the tardy reply Neil been away on hols.  Mine is also set to UK English using Firefox. Does the same in Win 10 & 11.

One of those things that are just sent to try us.

[duncan webster 1Participant @duncanwebster1]

Aluminium, it seems OK on my phone

[Author]

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