Add color to Goo CRT White

**Gregavi** · **09-22-09, 04:17 AM**

Can I add colorant (Grey) to Goo CRT white to make Goo Digital Grey, or is their more than just a color difference between the 2. If so, what specific color? I ask because a friend of mine has a small amount of CRT White leftover and I would like to make a Digital Grey sample board out of the leftover and compare it to his CRT white with my soon to be purchased Panasonic PT-AE3000U. Thanks in advance.

**mechman** · **09-22-09, 08:51 AM**

I'd ask the goo folks. But I really don't see why you couldn't. It really depends upon what kind of paint it is. I'd try adding black to it to make gray. And if you could send me a sample of the goo for spectro readings it'd be much appreciated!

**Harpmaker** · **09-22-09, 12:41 PM**

Welcome to the forum Greg!

From a quick look at Goo's website it seems that both the base-coat and top-coat are water-based paints. I think I would add small amounts of Liquitex Soft Body Acrylics Ivory Black to both the base and top coats until you reach the shade of gray you are after as both top and base coats look gray at Goo's site.

The bottle should look like this, only black.

It should be available at any art or craft store.

If you could, please send Mech a sample of the Goo base and top coats before and after you have tinted them.

He only needs about a 1 inch square sample of each, but a 2 inch sample would be better.

Good Luck!

**Gregavi** · **09-22-09, 06:38 PM**

Thanks guys for the reply. After I posted the question I spoke to the sales guy at Alternative Home Theater (where they sell the Goo system) and he said “Do not add any colorant to the Goo paint. It will ruin it” I asked him why and he really didn’t have a solid answer other than “It will ruin the reflective properties of the paint”. I’m not sure if that is really the case, but I don’t think I will chance it. Maybe I’ll use some for experimenting and see what the results are. I’ll keep you posted.

Thanks

**mechman** · **09-22-09, 08:02 PM**

I'd like to see pictures of the Goo. Take some when you get a chance.

**Harpmaker** · **09-22-09, 08:41 PM**

Greg, that's the answer I would have expected from Goo (or a Goo rep.). You might just call and ask them how they get it gray to begin with if added colorants "ruin" it.

I understand not wanting to chance ruining your Goo, but be advised that the white Goo won't tolerate even a small amount of ambient light without losing image contrast, that is why they need a gray Goo too!

Looking forward to your report no matter what you do with your Goo.

**Gregavi** · **09-22-09, 10:47 PM**

Quote:

Harpmaker wrote:

Greg, that's the answer I would have expected from Goo (or a Goo rep.). You might just call and ask them how they get it gray to begin with if added colorants "ruin" it.

Actually, I did ask him how they color it and he said he wasn't privy to that info, but somehow he did know that it would "ruin it". The only thing that makes me lean toward beleiving him is, what motive would he have for advising me not to add colorant if it were OK to do so?

Quote:

Harpmaker wrote:

I understand not wanting to chance ruining your Goo, but be advised that the white Goo won't tolerate even a small amount of ambient light without losing image contrast, that is why they need a gray Goo too!

If a white screen is so unadvisable, why does Goo and screen makers even make/sell them? I understand the whole CRT black level thing, but I was advised to use a white screen by the guy I will probably buy my Panasonic PT-AE3000U Projector from. He said it is the setup he uses and "it looks great". The screen choice process is far more complicated than I ever would have thought. It does force me to get educated on the subject though. That's the plus side. I have to make a decision on this because I ended up bidding and winning a CRT White Kit (2.3 L. each of base and top coat) on ebay today. Fortunately, the kit has enough to make 2-100"+ screens, so I can experiment with it. I think I'm gonna add some of the colorant that Harpmaker recommended to it and hope for the best. I will be applying this to a single peice of 3/4" MDF, 54"X96" (110" Dia. Yes they do make MDF in sheets larger than standard 4'X8'). Maybe I'll do one side white and the other with the grey added. I'll keep you posted. Thanks for the input.

**Harpmaker** · **09-23-09, 12:14 AM**

I would say the incentive to not have you color your own mix could come from them wanting to sell you a gray Goo kit, but perhaps I'm just too cynical.

I really don't know how neutral in shade (including white) their mixes are, and if they were REALLY neutral there is a chance your adding your own color would make the mix less neutral in shade as you darken it.

As I said, I really do understand not wanting to chance messing up their mix by adding black to it to darken the mix to a gray. I certainly don't want to appear to be pressuring you into doing something you don't want to do. Do what you are comfortable with and nothing more.

White screens are great if you have a "bat cave" of a theater where ambient light is not a consideration AND the projector being used has black blacks. Under those circumstances a screen that is a flat bright white would be just about perfect since it would give you a bright image that could be viewed at almost any angle. The problem comes when either there will be some other light in the room (causing the image to lose contrast and color depth) OR the PJ being used has blacks that look gray and not black. In those circumstances you would want to use a gray screen to combat those problems.

**Gregavi** · **09-23-09, 04:20 AM**

Well, I only know what I have read about my PJ but haven't seen it for myself since I have not ordered it yet, but what I have read is the Blacks are pretty good, especially for an LCD engine. I can make it into a "Bat Cave" if I choose, especially at night. I'm kinda likin' my idea of having 2 screens, one on each side of my MDF board. It will be a bit heavy, but managable. I'll just have to come up with some kind of mounting system that will make it fairly easy to flip over, without causing damage. I will report back. Thanks

**mechman** · **09-23-09, 12:02 PM**

Black is non existent on a projector. Black comes from the lack of light projected from your projector.

Something to keep in mind.

**Gregavi** · **09-23-09, 09:29 PM**

Quote:

mechman wrote:

Black is non existent on a projector. Black comes from the lack of light projected from your projector.

Something to keep in mind.

Good point. Why then do CRT projectors produce better blacks ? If the screen is white, the screen is white.

Anybody ever tried a black screen?

Also, I just read about a company (Vutec Silverstar) that uses crushed glass in their screen make-up. Sounds interesting and raises the question for DIYers. Anybody tried crushing glass into the mix? You could probably use a fabric sack and sledgehammer and a sacrificial Cuisinart to crush glass. Come to think of it, isn't sand crushed glass? Anybody tried sand in the mix? I'm tempted to try sand.

**mechman** · **09-23-09, 09:50 PM**

The problem isn't finding the proper things to use. It's trying to apply them. We've done a lot of tests with glass beads. The biggest hurdle that needs to be overcome is getting an even application.

I'm unsure why CRTs supposedly produce better blacks. To be honest I'm completely unfamiliar with them. Less light leakage maybe?

You're kind of in the minority with a CRT. Most folks have a digital projector nowadays due to their low cost. And the latest digital projectors rarely require a screen with gain - they have more than enough lumens to spare.

**mechman** · **09-23-09, 09:55 PM**

I should add that there are pictures of the Silverstar in the silver fire review. Had to get a comparison to a commercial product.

I'll have the Vutec and Stewart reviews finished up later this fall.

**Harpmaker** · **09-23-09, 11:00 PM**

Quote:

Gregavi wrote:

Good point. Why then do CRT projectors produce better blacks ? If the screen is white, the screen is white.

As I understand it, the reason CRT systems have the blackest blacks is because they are literally colored light tubes. You have one tube for each color, red, blue and green; white is a combination of all the tubes and black is when none are lighted (or "excited"). Each tube generates it's color by electrons striking a phosphor coating at the end of a vacuum tube (cathode ray tube).

DLP and LCD TV's or PJ's work in a totally different way. A DLP reflects white light that passes through a filter wheel with numerous colored filters in it and thus is being illuminated all the time so even totally black scenes get some light, but generally they give darker blacks than LCD systems do since LCD's actually block portions of light from coming through the screen (the same way your computers LCD monitor does) so to produce black they try to block all the light coming from behind the screen, but there isn't 100% blockage. That explanation was probably as clear as mud... to get a better understanding of how each of these systems work, hit the internet and I'm sure you can find some illustrations that are much clearer than my text.

Quote:

Anybody ever tried a black screen?

A member of another forum actually did this, and it worked after a fashion, but you need a REALLY bright PJ along with a small screen (by projection standards) for it to work. In his testing he had to get the PJ so close to the black screen that he couldn't focus the image.

Quote:

Also, I just read about a company (Vutec Silverstar) that uses crushed glass in their screen make-up. Sounds interesting and raises the question for DIYers. Anybody tried crushing glass into the mix? You could probably use a fabric sack and sledgehammer and a sacrificial Cuisinart to crush glass. Come to think of it, isn't sand crushed glass? Anybody tried sand in the mix? I'm tempted to try sand.

I actually will be ordering some microscopic glass flakes to try out in a screen mix. My main concern is that they will have a prismatic effect similar to mica flakes. We'll see.

DON'T try to make your own flakes by breaking or crushing regular glass yourself! This is VERY dangerous and you have no control over the size of particles produced. Besides the threat of being cut, you could also create glass powder so fine it goes air-borne and you, or others in the area, could breath that into your lungs - not good!

Common sand is too impure and/or fractured to be as reflective as a screen ingredient needs to be. Also, the size of the sand grains are too large. Some years ago I needed to build some ramps so my grandmother could use her wheelchair to get to street level and we could take her out to eat, medical appointments, etc. I learned that the way you increase traction on a painted wooden ramp is to paint it and then sprinkle dry sand on the wet paint! It worked like a charm!

**Gregavi** · **09-23-09, 11:06 PM**

Quote:

mechman wrote:

You're kind of in the minority with a CRT.

I don't have one, just curious as to why the perception that they produce good enough blacks that you can, and should, use a pure white screen.

**Gregavi** · **09-23-09, 11:16 PM**

Very interesting thread.

I understand the different technologies, it's the CRT projector I don't get. It still has to produce black on a white screen. I guess it can just produce black on to a screen Mo' Better.

I have decided to add some black (to make gray) to my Goo (base and top coats, as Harpmaker suggested) and see what happens. I am a ways off before I get to that point though. I'm in the framing stage.

**Harpmaker** · **09-23-09, 11:31 PM**

Quote:

Gregavi wrote:

I understand the different technologies, it's the CRT projector I don't get. It still has to produce black on a white screen. I guess it can just produce black on to a screen Mo' Better.

Actually, no projector "produces" black since black is the absence of light. That is why CRT PJ's must be used in a "bat cave" to get the best picture. A black area on a screen is simply that area without any light from the PJ hitting it. CRT's are better at not producing light in "black" areas of a scene than other display technologies.

**AH Theatre** · **11-02-09, 04:03 PM**

Quote:

Gregavi wrote:

Thanks guys for the reply. After I posted the question I spoke to the sales guy at Alternative Home Theater (where they sell the Goo system) and he said “Do not add any colorant to the Goo paint. It will ruin it” I asked him why and he really didn’t have a solid answer other than “It will ruin the reflective properties of the paint”. I’m not sure if that is really the case, but I don’t think I will chance it. Maybe I’ll use some for experimenting and see what the results are. I’ll keep you posted.

Thanks

Great forum here and glad I stumbled upon it. I'm the guy Gregavi spoke to, I'm not the manufacture but I'll try to elaborate a bit more, Goo Systems is a division of Tri-arts manufacturing which manufactures some of the highest quality artist paints in the world, all of there pigments are custom blended and ground using proprietary equipment for the sole purpose of reflecting light, Screen Goo does not use any extenders which are found in off the shelf paints to substitute expensive pigments (this is fine to color your bedroom wall but not if your trying to reflect complex colored light patterns produced by video projectors). Trying to add an off the shelf colorant to the reflective basecoat will completely change it's reflective characteristics and adding a colorant to the semi-translucent/diffusive topcoat will affect how light will travel through it if at all. Hope this helps.

**Harpmaker** · **11-02-09, 05:43 PM**

Hi Zman, welcome to the forum!

According to the info I've read from Liquitex they don't use extenders either, even in their soft body acrylics; and my question still stands about how Goo creates their gray mixes. If Goo wasn't so expensive I would try this experiment (adding black artist acrylic to "white" Goo) myself.

Do you know what the reflective ingredient in Goo mixes is?

**AH Theatre** · **11-02-09, 06:18 PM**

Quote:

Harpmaker wrote:

Hi Zman, welcome to the forum!

According to the info I've read from Liquitex they don't use extenders either, even in their soft body acrylics; and my question still stands about how Goo creates their gray mixes. If Goo wasn't so expensive I would try this experiment (adding black artist acrylic to "white" Goo) myself.

Do you know what the reflective ingredient in Goo mixes is?

Thanks for the welcome.

Screen Goo's front projection coatings all start out as there reference CRT White coating to which they add colorants designed specifically for there screen coatings. Adding a black artist paint (even Tri-Arts) would diminish it's performance.

I hate to disappoint but there isn't a specific single ingredient that makes Screen Goo reflective, rather it's a combination of premium acrylics with very low light absorption characteristics, high concentration of pigments that have gone thru Goo Systems proprietary dispersion and treatment techniques to maximize there reflective properties and the knowledge to be able to put it all together.

**DavidHawke** · **11-02-09, 07:49 PM**

Not trying to be rude, but it sounds like a lot of smoke and mirrors to me. A case of "Emperor Goo's new clothes."

I'd be willing to bet that Liquidtex (or Lowes/HD paint department tints) could tint white Goo to acheive similar results as Gray Goo. My only concern would be that it might require adding drops of a few colors in addition to black to achieve the desired neutral gray. Most of the neutral N8 and N9 shades, are composed of drops of 2 or 3 different colored pigments added to the white base. If you could take a sample of Winter Mist, or another known OTS neutral gray into Lowes... along with a quart of white Goo base, they can measure it on the X-Rite color matching computer to determine exactly how many drops of each pigment is needed to to make it match the neutral gray shade you have a sample of. They (Lowes & Home Depot) have this function built into their paint mixing systems, so that they can add pigment to an existing can of paint (to correct the color) if they initially got the color recipe a bit wrong.

Not sure if I'd tint the top coat though. I'd speculate that Goo acheives some of its gain boost with the translucentcy of the top coat. I'd suspect that tinting the top coat would destroy its ability to increase gain. If their topcoat truly is grey, as one of the senior members suggested.... then maybe there is something to Goo's claims.

I'd assume that Goo only wants us to believe that they use a blend of unique and exclusive ingredients. If the public stops believing this... then nobody would pay Goo $120 for 2 quarts of paint anymore.

Of course, I could be completely wrong and this might very well ruin your Goo. However, it would be interesting to try it, if you had an extra quart of Goo. A half quart would probably work as well. You would simply have to have the Lowes employee reduce the drops of pigment suggested by the X-Rite for a quart, in half.

**AH Theatre** · **11-02-09, 08:00 PM**

Your not being rude at all, different opinions and view points help us all to learn. But perhaps I'm missing the point on something, why would anyone want to alter white Screen Goo to try and make a grey coating when you can buy one of Goo Systems grey coatings that are ready to use out of the jar? The cost of the white and grey coating are the same.

**DavidHawke** · **11-02-09, 08:27 PM**

I thought he said that he won the white Goo cheap on Ebay... and he was hoping to modify it to Gray, rather than actually shell out another $120 for the Gray version.

I agree with you. It would be easier to just buy the gray version from the get-go. It sounds like he's trying to make due with what he won for cheap in an Ebay auction. I can't blame him... If I scored the white Goo cheap, I'd probably want to tint it gray as well.

**Gregavi** · **11-02-09, 11:10 PM**

I did win some white on ebay but after doing some research (I was advised by several projector salesman to use a white screen with my Panasonic PT-AE4000U Projector) I decided to keep it white.

I then decided not to use it at all because I made the decision to buy an electric roll-up screen so I could place my 50" DLP TV behind it so I wouldn't have to fire up my projector to watch "non worthy" programming. (Those replacement bulbs are not cheap.) I purchased 2.3 L of Goo (Base & Top Coat) so I had plenty to experiment with, but I sold it for a little bit of a loss. Oh well, I guess someone else will have to experiment with it.

Note: ZMan was very professional and courteous when I spoke to him on the phone and I want to thank him for his help. I was looking forward to using Goo but my new plan was a no brainer once I thought through my options. It takes a lot of time to design the ultimate home theater, not that mine will be as ultimate as some...

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