Should you sand every coat?

If not, when and with what products?

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Jaeger.
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darrenc wrote:

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

I assume you are talking about wood.

I use wet and dry paper inbetween coats

Wood, Metal, Plastic, Bricks, Concrete but not walls of plaster, that'd be a more stupid question!

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Jaeger.
Senior Member doesn't mean I'm OLD!

darrenc wrote:

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

suggest sanding if and only if the previous coat on any sub-strate has not taken...or has (I think the technical term is to be de-nibbed...) not a pro...

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I Know it says I'm On-line, but I might have just left myself logged in, whilst I'm out....

I agree with the de-nibbing and complete stripping, but what about

Oil Undercoat and then Gloss top coat, or

Acrylic undercoat and then top coat. Or

Oil base, acrylic undercoat and acrylic top coat?

Does a primer need to be keyed, after all it is a primer?

Does an undercoat need a key as it was intended to have a top coat applied?

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Jaeger.
Senior Member doesn't mean I'm OLD!

darrenc wrote:

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

I thought you lightly sand between coats to de-nib and maintain a key (as Wino says) regardless of which covering you're using.

Hi Krispy,
I agree.
I'm thinking out loud, but you can see my point?

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Jaeger.
Senior Member doesn't mean I'm OLD!

darrenc wrote:

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

Never sand bare plaster but i always pole sand after the mist coat.
Timber such as doors, windows architraves i always sand down between coats to de-nib and create a key. I dust off before u/c and vacuum off before glossing/top coating. I'd use the same system regardless of paint medium.
Metal, first thing to do is de-grease (if bare) then prime and do the same as timber.
The thing you have to understand is paint needs a key regardless of what your painting. There are exceptions such as plastic which i was always taught to apply gloss directly to, there are specialist primers but i have to say the guy that told me to do it writes the P&D manual so i doubt very much he's wrong.
Cement based products cant really be rubbed down but have a natural key anyway. Its usually more a case of cleaning prior to painting.

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

-- Thu Jul 01, 2010 9:49 am --

Thought I was at "Painter's Pit Stop" there for a moment?

So back to the answer to the question.

Lets make it more restrictive.

Assume dust free environment (so take de-nibbing out of the equation), undercoat applied beautifully so laid off and no brush strokes to contend with.

Having applied 'the perfect key" as stated by Dulux in their data sheets, should it be rubbed down with abrasive papers?

_________________
Jaeger.
Senior Member doesn't mean I'm OLD!

darrenc wrote:

I dont think its a stupid question but does show a lack of understanding of how paint works and reasons for certain applications, now dont jump down my throat Jaegar i'm not being funny its just a classic case in point of a well educated professionally trained painter against a general tradesman.

Not a stupid question at all.

Having applied 'the perfect key" as stated by Dulux in their data sheets, should it be rubbed down with abrasive papers?
No, not really. Sometimes there's far too much vigorous sanding down goes on.

There are many instances where there's really no need to rub down and many instances where you should.

Some folk are always excited about Bulls Eye and Bin. Take a look on the side of their tins, it says "sticks to all surfaces without sanding". I don't say it, Zinsser do.

It's your choice.

Only to denib if necessary in my opinion unless you are using Weathershield solvent based.

I very rarely see in between coats peeling with solvent based wood paints. (I cannot even remember the last time, but it was probably due to dirt). It comes off the wood yes. Its like saying it is better to use araldite and screws and no more nails to fix skirting boards, yes better but a waste of time. Only if there is a barrier layer of dirt / grease will it be necessary.

I do see gloss peel off of plastic time and time again, so I prime that.

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