Am I in the right place...???

[LB476]

Problem:- I am decorating my flat with white emulsion and when I come to do the second coat it is hard to see where the first dry coat ends and the second wet coat begins.

Using a bright inspection light placed at the right angle it is possible to see a slight contrast between the dry paint and the wet paint. However, this still means you have to keep moving the light source and the observation point to detect this minimal difference...

I was thinking if I changed the colour of the light source and wore tinted glasses this could increase the contrast between the coats.

This sounds like a physics question to me. Which colour combination would give the greatest contrast...??? For practical reasons the light source needs to be readily available, perhaps Infrared or UV, or just use a tinted glass filter on the white inspection light. Similarly, inspection glasses are produced with grey, black, blue or yellow lenses...

Thank you in advance for your input.

[DrP]

Some companies have paints that do change colour as they dry (from pink to white for example) to get around the problem you are describing.

As for your current position though - you just have to do your best to paint the surface systematically so that you cover the whole area. I would guess that good lighting would help you see the fine line between the dry paint and the fresh coat - good luck.

 

Edited October 3, 2018 by DrP

[Strange]

28 minutes ago, LB476 said:

Problem:- I am decorating my flat with white emulsion and when I come to do the second coat it is hard to see where the first dry coat ends and the second wet coat begins.

Maybe, if you can’t see the difference it means you don’t need a second coat

 

[StringJunky]

28 minutes ago, Strange said:

Maybe, if you can’t see the difference it means you don’t need a second coat

 

Yeah, it only really matters if the job is functionally critical.

[DrP]

26 minutes ago, StringJunky said:

Yeah, it only really matters if the job is functionally critical.

You mean like a fire retardant coating that needs a specific build to work as advertised?

[StringJunky]

2 hours ago, DrP said:

You mean like a fire retardant coating that needs a specific build to work as advertised?

Yes,

[LB476]

Problem:- I am decorating my flat with white emulsion and when I come to do the second coat it is hard to see where the first dry coat ends and the second wet coat begins.

Using a bright inspection light placed at the right angle it is possible to see a slight contrast between the dry paint and the wet paint. However, this still means you have to keep moving the light source and the observation point to detect this minimal difference...

I was thinking if I changed the colour of the light source and wore tinted glasses this could increase the contrast between the coats.

This sounds like a physics question to me. Which colour combination would give the greatest contrast...??? For practical reasons the light source needs to be readily available, perhaps Infrared or UV, or just use a tinted glass filter on the white inspection light. Similarly, inspection glasses are produced with grey, black, blue or yellow lenses...

Thank you in advance for your input.

[StringJunky]

Did you lose your other thread on this?

 

[LB476]

Nope

 

[John Cuthber]

Other brands/ stores are available but...

https://www.diy.com/departments/dulux-brilliant-white-matt-emulsion-paint-2-5l/1759077_BQ.prd?utm_source=google_cpc&utm_medium=shopping&utm_campaign=PX_GSC_Surfaces_+_Generic&ppc_type=shopping&ds_kids=92700029904931240&gclid=EAIaIQobChMIocPn9JLs3QIVRLTtCh2yWQXzEAQYASABEgIUD_D_BwE&gclsrc=aw.ds&dclid=COO8-_aS7N0CFUVFGwodVYkKqg

[StringJunky]

27 minutes ago, John Cuthber said:

Other brands/ stores are available but...

https://www.diy.com/departments/dulux-brilliant-white-matt-emulsion-paint-2-5l/1759077_BQ.prd?utm_source=google_cpc&utm_medium=shopping&utm_campaign=PX_GSC_Surfaces_+_Generic&ppc_type=shopping&ds_kids=92700029904931240&gclid=EAIaIQobChMIocPn9JLs3QIVRLTtCh2yWQXzEAQYASABEgIUD_D_BwE&gclsrc=aw.ds&dclid=COO8-_aS7N0CFUVFGwodVYkKqg

Going to get some.

Quote

Features and Benefits
Dulux magic white matt emulsion helps you to achieve the perfect patch-free finish for your ceiling. Specially formulated to fade from pink to white within an hour. Dulux magic white gives you time to check whether every corner is perfectly painted or not

 

[swansont]

!

Moderator Note

Identical threads merged. One thread per topic, please.

 

[LB476]

58 minutes ago, swansont said:

!

Moderator Note

Identical threads merged. One thread per topic, please.

 

Perhaps you could move the entire thread to the relevant Physics subsection, as the engineers seem to have come up dry...???

Always assuming there is a different audience there...

Thank you  in advance for your kind attention.

[DrP]

Just now, LB476 said:

Perhaps you could move the entire thread to the relevant Physics subsection, as the engineers seem to have come up dry...???

What more do you want? There are paints that are on the market that dry from one colour to another to get around the exact problem you describe. For your system, you could try a finger touch where you think you might have missed the 2nd coat if it is that difficult to tell the boundary or, as I suggested, paint it with a system...  i.e. start top right and work down and across to ensure you cover each part.  There is no magic way of improving your eyesight.

 

[swansont]

39 minutes ago, LB476 said:

Perhaps you could move the entire thread to the relevant Physics subsection, as the engineers seem to have come up dry...???

Always assuming there is a different audience there...

Thank you  in advance for your kind attention.

!

Moderator Note

You aren't likely to get a different audience there.

 

[LB476]

2 hours ago, swansont said:

!

Moderator Note

You aren't likely to get a different audience there.

 

Thanks.

Appreciated all the input, although I was looking for an answer to that specific question, not alternative solutions...

Bye bye.

[Frank]

Extrasensory colour perception - might be an app for that, one that exaggerates the colour differences it sees the same way an app can be used as a magnifying glass.  Depends on the camera sensor's colour sensitivity.  Filters might prove handy because of the limited colours actually perceived by camera sensors (red, green and blue), same as our eyes.  When it comes to paint though, different light will interact with the paint reflection spectra(?) which may in fact include colour wavelengths we interpolate.  This isn't as likely a problem in the given case where we want to discern between wet and dry or between new and old.

 

[Endy0816]

1 hour ago, Frank said:

Extrasensory colour perception - might be an app for that, one that exaggerates the colour differences it sees the same way an app can be used as a magnifying glass.  Depends on the camera sensor's colour sensitivity.  Filters might prove handy because of the limited colours actually perceived by camera sensors (red, green and blue), same as our eyes.  When it comes to paint though, different light will interact with the paint reflection spectra(?) which may in fact include colour wavelengths we interpolate.  This isn't as likely a problem in the given case where we want to discern between wet and dry or between new and old.

 

lol, there is actually.

Reality Hacker for the Android. Can apply various filters in real time.

https://play.google.com/store/apps/details?id=com.visor.visionhacker&hl=en_US

It was still pretty faint but could identify a wet area via Inverted Sorbel Edge. There's different options including color filters though.

[Frank]

15 hours ago, Endy0816 said:

lol, there is actually.

Reality Hacker for the Android. Can apply various filters in real time.

https://play.google.com/store/apps/details?id=com.visor.visionhacker&hl=en_US

It was still pretty faint but could identify a wet area via Inverted Sorbel Edge. There's different options including color filters though.

Yeah, very close, maybe suggest a "painting" or "wet paint" filter to highlight subtle colour differences, might help to turn on the flashlight too.

 

[John Cuthber]

Just a thought.

Emulsion paint dries because the water evaporates and that draws in heat.

In principle, a sensitive thermal camera could spot the wet paint.

If you chose a camera with the right spectral sensitivity and a light source of the right wavelengths, it could "see" the liquid water.

You might even be able to find a setup where an IR camera could distinguish the pink paint from the white.

[studiot]

What is all the fuss about?

Two (or more) coats are used because it is pretty well impossible to achieve complete coverage without minute holes in the paint film using only (despite the adverts).

So long as the second coat fills these holes it doesn't really matter if its coverage is not so good on the bits that have already been painted.

For instance, surely you only do the cutting in once ?

[John Cuthber]

16 hours ago, studiot said:

Two (or more) coats are used because it is pretty well impossible to achieve complete coverage without minute holes in the paint film using only (despite the adverts).

In my experience it depends what's underneath.

If you are covering  over some other colour or pattern you need several coats to do it. If you miss patches in one of the coats you can see the underlying surface through it.