What color would a door painted with ultraviolet paint appear to be?

[Grimstone]

I have a question, and forgive me for not presuming you have the same basic knowledge as my self. but I want there to be no doubt about the question when it is given.
Light is a very wide spectrum from low end Inferred ultra violet the high end.

<<----IF------------------------UV------------------->>
<<----IF-------[human eye]-----UV------------------->>
now the human eye can only see a small sliver of that spectrum. and we refer to that as visible light. although other animals can actually see better than we do.

We look at the ball and see it is red. Because the Surface reflects that band of the light spectrum back and the rest is absorbed. this is, in essence, how we see color. Dogs are color blind, but seem to see better at night than we do.
We can set up a computer mechanical device that can do color matching (home depot,etc etc.) so.
If Bob used a color matching device to match the ultra violet just outside our range of "visible spectrum" and used that to paint a door. When Tina looks at the door, What will Tina see?

I do not believe that the "ultraviolet paint" that you have to use a black light on to see, is "true Ultraviolet" or else when I turn on a black light. my white shirt is suddenly ultraviolet as well.

I have heard
A. the door would be black, a lack of light, as none is reflecting back that we can see.

B. the paint would not alter the light at all and you would see the wood grain under it.

C. a shimmering wall as light "flecks" escaped and our eyes would perceive them.

D. It would look like a black hole man, no light reflecting off it, it would be a black hole.
[I don't take bob serious to often]

I believe A. is correct but can't completely rule out B as i have no means to test this.
But I Do disagree that it would look like a black hole.

what say you?

 

[pallidin]

Ultraviolet light is not detected by the human eye.
Yet, ultraviolet light can cause some substances to emit a visible spectrum.

 

[Grimstone]

Ultraviolet light is not detected by the human eye.
Yet, ultraviolet light can cause some substances to emit a visible spectrum.

Please re-read this part.
""We can set up a computer mechanical device that can do color matching (home depot,etc etc.) so.
If Bob used a color matching device to match the ultra violet just outside our range of "visible spectrum" and used that to paint a door.""

I understand that it is beyond the range of the human eye. As I said above.
If the only light being reflected off the door is ultraviolet light and the human eye can not see that range. what do we see? a lack of color? (see through the paint) a lack of light ( a flat black space with no light) or what?
That IS the point of the question.

 

[DrDu]

I don't understand your post at all:
a) What is a "visual question"?
b) The device you are talking about, matches the ultra violet to what?
c) Why does this device need to be computerized?

 

[Born2bwire]

I think a better question would be, "If we went into a dark room and turned on an ultraviolet source, what would we see?"

Still, in all these questions the answer really doesn't have anything to do with ultraviolet light but with the underlying properties of the surroundings. We can't see ultraviolet light but we can see its effects. Ultraviolet light can cause dyes and materials to fluoresce (or would that be phosphoresce... well it makes it glow but either mechanism can occur depending on what we have). In fact, one of the ways that your detergent and bleach make your whites whiter and your brights brighter is by the fact that they add dyes to the clothes that glow under ultraviolet light. Hence, they seem even whiter and more brilliant in the sun. So if we have an ultraviolet source what we may see is the glow that arises from its interaction with objects and materials around the room.

If you have some kind of paint that emits ultraviolet light then what you see has to do more with the other properties of the paint. Paint and dyes typically absorb light and reflects only a narrow spectrum of the light absorbed. So red paint absorbs the visual range and only reflects red light. So does your paint absorb visual light (and other ranges of frequencies) and only reflect ultraviolet light? If so then it would appear black. Or does it not interact with visual light and transmits it with little impact? If so you would see the underlying door as if it had not been painted at all. Just because it is opaque in one spectrum does not mean it is opague or transparent in another spectrum unless you know about its behavior at all frequencies. Take water for example, it is fairly transparent in the visible region but it is pretty good at absorbing infrared.

 

[Grimstone]

I don't understand your post at all:
a) What is a "visual question"?
b) The device you are talking about, matches the ultra violet to what?
c) Why does this device need to be computerized?

DrDu.
I don't understand your post at all:
a) What is a "visual question"?
b) The device you are talking about, matches the ultra violet to what?
c) Why does this device need to be computerized?

What i do not understand is how someone who is in an advanced class in physics, can not understand
someone simple as my self.

1. What is a Visual question
A. the whole thing is based on the fact that someone is looking at a door. the light and the color all have to do with the Visual aspect of this. the "What would you see" part is called a question.
(I do not like being "trolled")

2.-3. as light is reflected off a surface and that light is what the human eye uses to perceived color.
then yes. we would have to rely on a machine to match the pigmentation necessary to make a true ultraviolet paint.

3. see #2.

 

[Grimstone]

Born2bWire.
1. ""I think a better question would be, "If we went into a dark room and turned on an ultraviolet source,
what would we see?"""

1,a.That is no where near what I asked. and you would if the room was 100% absent of light, and the
ultraviolet light sorce was 100% in the bandwith of ultraviolet.
you would see darkness. there would be no light for your eyes to receive and translate into an immage
your brain could translate.2. ""Still, in all these questions the answer really doesn't have anything to do with ultraviolet light
but with the underlying properties of the surroundings.""

2.a how does my question not "have anything to do with ultraviolet light"? the paint used only gives reflects
light in the ultraviolet spectrum.

3. ""Ultraviolet light can cause dyes and materials to fluoresce (or would that be phosphoresce... well it makes
it glow but either mechanism can occur depending on what we have). In fact, one of the ways that your detergent
and bleach make your whites whiter and your brights brighter is by the fact that they add dyes to the clothes
that glow under ultraviolet light.""

3.a I am not talking about chucky cheese where you walk in a black light and your shirt glows. that's is not
ultravilet light spectrum.


4.""So does your paint absorb visual light (and other ranges of frequencies) and only reflect ultraviolet light?""
4.a Yes, as any other paint would on a door.

""If so then it would appear black""
Thank you. your answer is "it would appear black"

 

[Grimstone]

Ladies and gentlemen. I come here with questions because as a Physics Forum for the following reasons.
1. you are taking classes That I never got to take.
2. I believe that you are in fact smarter than I am.
3. Should I present a challenging idea during a question. you might help me work through it.
4. I always ask you to use the K.I.S.S. method as i am not capable of understanding the techno jargon.

 

[Drakkith]

IF the paint only reflects UV light and absorbs ALL light of the visible spectrum, it would be black. Is that the answer you were looking for?

There could still be a paint that reflects the same UV light, but also reflects Blue light as well, in which case it would look blue.

 

[Grimstone]

The thing is. I am not looking for a specific answer. I am looking for the right answer. my room mate thinks it would be a black hole effect. that is its flat black no light what so ever.

I do not agree with him. I believe it would be clear and you would see the wood under the paint.

 

[sophiecentaur]

This question confuses Colour with Spectrum. The spectrum of light which is reflected by a surface is quantifiable and measurable. Once your eye has analysed this spectrum, your brain assigns it a Colour. Many different spectral combinations can produce the same subjective impression and, hence, be seen as the same Colour. This is why Colour TV and printing etc, etc, work so well.

If you and I have 'normal' colour vision, then we will agree (our common language) on what to call a red ball or a blue door. Moreover, we are likely to agree what to call many more subtle colours / shades. A colour blind person may learn (sub-consciously, even) to compensate for their 'abnormal' analysis by using contextual clues and find that they also agree about how to name many colours reliably. However, there are tests (Ishihara colour blindness test, for instance) that will reveal non-standard / inadequate colour perception.
Basic message: COLOURS ARE IN YOUR HEAD and nowhere else.

 

[Drakkith]

The thing is. I am not looking for a specific answer. I am looking for the right answer. my room mate thinks it would be a black hole effect. that is its flat black no light what so ever.

I do not agree with him. I believe it would be clear and you would see the wood under the paint.

Like I said in my previous post, if the paint reflected only UV light and absorbed all other light it would look black to you and I. If it allowed visible light light to pass through it then you would see the wood underneath.

 

[Rap]

Drakkith is right. If you take a piece of glass and paint it with your ultraviolet paint and hold it up to a visible light, will it look black or clear? If the paint absorbs everything but ultraviolet and only reflects ultraviolet, then it will look black on the glass. On the door, it will look black too, because the only thing bouncing off the door and hitting your eye is ultraviolet, which looks black. If the paint reflected ultraviolet and was transparent to visible light, then the glass would look clear, and on the door you would see the wood grain, because the visible light would go thru it, bounce off the wood, go thru it again and hit your eye.

 

[Born2bwire]

The thing is. I am not looking for a specific answer. I am looking for the right answer. my room mate thinks it would be a black hole effect. that is its flat black no light what so ever.

I do not agree with him. I believe it would be clear and you would see the wood under the paint.

Haha. So you mean that you are looking for the answer that agrees with your own presuppositions.

I think more than one of us has already provided you with the proper answers. Rap, Drakkith and myself have all stated the same response.

 

[Grimstone]

Then the answer could only be found by actually making the paint.

(to find out if the pigments required to reflect ultraviolet light, would in fact absorb all other spectrum's or allow them to pass through.)

if the paint is Translucent/transparent then the human eye would see a gloss.

IF the paint is Opaque then the door would be black.

So i know how to get the answer. but am unable to do so.
Thank you guys.

 

[Claude Bile]

The UV paint will be black.

The reason is because paint mixing is a subtractive process. That is, if I want a red paint, I need to include pigments that remove (absorb) both blue and green, leaving only red to scatter/reflect.

Therefore, if I want a paint that looks purely UV; that is, UV that includes no red, green, blue etc., it will necessarily absorb red, green, blue etc. If we can only perceive visible colours, then the UV paint will appear black.

P.S. UV paint does exist, and does look black.

Claude.