Improving an electric rolling screen

[Harry-Greece]

Hi all,

When i bought my projector (Panasonic PT-AE2000), i also bought a cheap 80" electric screen since i heard a lot of wrinkle/sag horror stories about manual pull down screens.

The screen is convenient, but the surface of the projection screen was AWFUL.

Even from 3m (10ft) away, i could see the "texture" of the screen which looked like "stationary" noise in the picture, and was particularly annoying in bright colours.

So my first thought was to find a kind of "flexible" paint that could be used to paint the screen, while at the same time being elastic enough to resist cracking when the screen is rolled up and down.

After a lot of search, i found a Greek Made Vinylacetate - Ethylene Copolymer based white paint that can be used for painting roofs and seal cracks in the walls and i tried it on my screen!

The results were astonishing! The ugly texture of the screen was smoothed out, and the picture is now more detailed, with better blacks, and better saturation.

The only drawback is that the screen is a bit "sticky" and the material sticks to its self when you roll up and down. I have compensated for this by adding extra weight to pull the screen and unstick it when i roll it down. This aspect still needs refinement! LOL!

However, i have lost a few lumens by this treatment, and for the second "Phase" of my experiment, i am thinking of making a mixture of this paint, along with pure aluminium powder to increase the gain a bit.

It took me some time to find Pure Fine Aluminum Powder, but eventually i managed to find such a product (produced in Germany) at an Arts and Crafts shop, in 1Kg (around 2lb) packaging.

However, the powder is so fine, that you need to take extra precautions when you use it (goggles, breathing mask filter etc), but the result will be worth the risk.

I'd like to ask if anybody has experimented with pure aluminum powder, and also if i can have a guideline as to the amount of aluminum i should add in the white vinylacetate paint, to increase the gain (but still keep hotspots in check).

Thanks!

[Harpmaker]

Hi Harry,

Welcome to the Shack!

Thanks for posting your ongoing screen experiment. It's very interesting!

I have a few questions for you, but first I need to caution you about using pure powdered aluminum - this stuff can be VERY dangerous. Besides not being healthy to inhale, pure aluminum powder tends to catch on fire, and make a VERY HOT fire, unless treated properly. Also, the combustion process is not necessarily fast, but can occur over hours or even days! Unless you really know what you are doing, I suggest not trying to use aluminum powder and instead find some aluminum-based paint to add to your white paint. If you do decide to try using aluminum powder (even commercial paint companies use special aluminum paste when making aluminum paint, not powder), make sure it has been "passivated" which will make it safer to experiment with, but not really safe. If you do your own internet searching for these terms you will see what I mean.

Now for those questions.

Is the roof paint you are using water-based? If so make sure any additional ingredients you put in it are water soluble as well. You might also check with the same company that made your paint to see if they have an aluminum roof paint.

When you painted your screen, did the roof paint seem to dry to a thicker and heavier film than regular house paint, or is it just more flexible?

I'm looking forward to your continuing experimentation in this area!

[mechman]

Welcome Harry!

Yes I have experimented with raw aluminum powder. Sadly none of my experiments resulted in anything worthwhile. And I'll second harp's cautions. Working with raw aluminum powder is extremely dangerous and not for the average person. And mixing it with water tends to make the stuff even more volatile. Which is another reason we didn't venture far down that road nor have we ever recommended using aluminum powder.

I'd suggest looking into ordering some Auto Air Fine Aluminum from Germany or Switzerland. There may even be someplace in Greece that sells it. Check with auto body shops. They may know where to get it.

[mechman]

Auto Air Dealer Web Page

[Harry-Greece]

Harpmaker wrote:

Hi Harry,

Welcome to the Shack!

Thanks for posting your ongoing screen experiment. It's very interesting!

I have a few questions for you, but first I need to caution you about using pure powdered aluminum - this stuff can be VERY dangerous. Besides not being healthy to inhale, pure aluminum powder tends to catch on fire, and make a VERY HOT fire, unless treated properly. Also, the combustion process is not necessarily fast, but can occur over hours or even days! Unless you really know what you are doing, I suggest not trying to use aluminum powder and instead find some aluminum-based paint to add to your white paint. If you do decide to try using aluminum powder (even commercial paint companies use special aluminum paste when making aluminum paint, not powder), make sure it has been "passivated" which will make it safer to experiment with, but not really safe. If you do your own internet searching for these terms you will see what I mean.

Now for those questions.

Is the roof paint you are using water-based? If so make sure any additional ingredients you put in it are water soluble as well. You might also check with the same company that made your paint to see if they have an aluminum roof paint.

When you painted your screen, did the roof paint seem to dry to a thicker and heavier film than regular house paint, or is it just more flexible?

I'm looking forward to your continuing experimentation in this area!

Thanks for the replies of both of you guys and good to be with you in this Forum!

To answer your questions,
1. YES the paint is water soluble and the man at the paint company advised me to look for water soluble aluminum powder for my "experiment"

2. Depending how much water you are going to add the paint yes the paint can be thicker than regular paint, and it feels like a piece of rubber or vinyl when it is dry. It is very flexible and the company claims that you can stretch it around 8 times it's original size before breaking.

3. As far as the aluminum powder is concerned, i also had my worries about breathing that stuff, but reading what you mentioned above scared me even more!!!!
So i suppose the idea is "back to the laboratory" until i find an aluminum paste or paint that can be mixed with the white vinylacetate "paint".
I have also found some kind of Powder/Paste (it looked like moist powder) containing Silver, but it gave me the impression that it had a prism effect (maybe it contained Mica as well) as i could see the particles in many colours so i ruled it out.

It is certainly a challenge to try and improve a rolling screen, but definitely i'd love to share my findings in this Forum.

[Harpmaker]

That white roof paint sounds very interesting Harry. I've seen something similar here, but never got around to testing it for a screen mix.

Yeah, raw aluminum powder isn't something to be dealt with lightly. Back when I was researching adding it to house paint, I found a report about a guy that had some aluminized paint (roof paint I think) in his van. He had stopped at a restaurant to eat and while he was still eating the paint (in a sealed bucket) ignited like a road flare. The resulting fire was so hot the firemen couldn't put it out! All they could do was contain the area until it burned itself out. Of course, the van was totally destroyed. If I remember right, the cause of the fire was traced back to a batch of paint made with unpassivated aluminum.

If you saw a prismatic effect from that silver paste/mix it probably had a lot of mica in it. Good for a number of things, but, in my opinion, projector screens isn't one of them.

Your best bet is to find a source for the Auto Air Aluminum; but something else that might work is the bronze powders at the link below. These are real metallic powder that has been mixed with a type of glue and are designed to work with added water. They contain no mica. I have been meaning to test them, but I just have too many things to do right now. These are made in Germany, so maybe you can find a local source for them.

http://www.fineartstore.com/Catalog/...ost%2cUnitCost

Please continue sharing your findings here at the Shack! This is truly an international forum with folks from the U.K., Australia, Sweden, Egypt and more participating. Now we can add Greece to the list!