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Mystery of the CO2 Balloons!

Filled some balloons w  co2  from dry ice in a soda bottle.   As expected, they act like a lens, a magnifier of sound. No mystery there. Just as a dense glass refracts light, the denser gas refracts sound. The mystery is why balloons filled with co2  leak down faster than identical balloons filled by mouth. Yes, there is some co2 in my exhaled breath, but it is mostly  n2,  and  o2.  I would hav expected the n2 and o2 to leak out more quickly, being smaller molecules. So whatzup wit dat?

Topic by Toga_Dan    |  last reply


Instructable request: Animated (Hologram) childrens school rulers popular in the 1980's ?

Remember the plastic school rulers with the moving pictures on it - where the picture seemed to move as we moved the ruler - plastic refraction ones I think. Can someone please tell me how to make them at home. These rulers used to be quite popular a while back - now I cannot find them - so why not make them for my kids instead! :) Thanks.

Question by MicroKID    |  last reply


How do I determine the size of the image needed to reflect onto a cylinder (see Q for better description)? Answered

I plan to take a large disc shaped screen and then reflect that image onto a cylinder to create a holographic effect. Right now this is just a concept but I am wondering if this is plausible and what size the disk would need to be to create an image to cover the cylinder. If a formula could be provided that would be best or just a general explanation of how to find a formula.

Question by TheTechGuy99    |  last reply


How to build a ray box to use for a set of refractions/reflections? Answered

I would like to make a 'solid' ray box (not out of cardboard!), preferably with more than one slot, and shine the rays from it to a set of mirrors, prisms, and all different kinds of reflective/refractive materials. The light would bounce off quite a few medias so I imagine it needs to be quite strong, but again, how strong? I know I need a fresnel lense in order to make the rays coming out of my ray box parallel but what is the rule, what distance does the lense need to be from the source of light, and does it depend on the size and strength of the light? Thank you very much!

Question by matisha23    |  last reply


In Spain, looking for clear teflon tube for a lightpipe.

I guess this question has two parts. I'm prototyping a solar energy device, part of which is a light pipe to transport the collected solar energy, about 300 - 2500 nM. I'm planning on making this from a flexible tube filled with a highly refractive liquid, stoppered at each end with clear plugs. It looks like the materials I should be using are: Tube: Teflon (PTFE, FEP, AF 1600, AF 2400) in that order of desireablitity, lowest to highest. The AF 2400 has a refractive index of 1.29, which is the lowest of any polymer. Apparently. Core: Mineral oil / liquid paraffin. Plugs: Acrylic or normal glass. Thoughts? Also, where would you suggest I try to find these? (I have the mineral oil already) Keeping in mind that I'm in Madrid, Spain. Getting this to work would make a huge difference to solar microgeneration, as transporting the energy is currently a bit of a nightmare. Thanks heaps, Daniel.

Topic by SolarFlower_org    |  last reply


The Future of Invisibility

It is reported that a team of researches at the University of California, Berkeley claim to be on the doorstep of invisibility. Using a special type of metamaterial they are bending electromagnetic waves and negatively refracting visible light. Their ultimate goal is to render entire objects invisible to the naked eye. After reading this, I conducted some invisibility experiments of my own. Based on my initial experiments with invisibility cloaking, I must concede that we are not quite there yet, but are getting close (see image).For more information, read the full news report

Topic by randofo    |  last reply


Plastic Screen Media Decoder

Hi Guys. I've seen a print ad that had a plastic 'zigzaggy' decoder gizmo stuck to it,  that I could peel off and use to 'decode' media as I slid the plastic over my screen, over a particular picture on their website.  The refraction of the plastic would 'decode' the image. What on earth would this kind of mechanism be called?  I'm trying to Google 'something' of a how-to... Not having found anything, I'm turning to the craftiest bunch I know ;) Thanks for your help.

Topic by Saeven    |  last reply


Could I build a giant magnifying glass? (And maybe incorporate it into a steam engine?)

Optics are fun, and so following that logic, scaled up optics should be even more fun. And so this leads us to: How do I build a giant magnifying glass?The sun has a lot of power, and I want to harness that energy, and try out a few things, including the interesting prospect of using it to power a steam engine. (Heat up something, run water over it, and run the steam through a turbine).Several methods have come to mind, including: acrylic, freezing some water in specially-shaped bowls, and sandwiching water (which has a slightly higher refractive index than ice) between two parabolic pieces of plastic. I'm personally concentrating on the last one, as it would be more permanent than the ice.Just thought this up: freezing a lens, and then coating it with something immediately so that it will stay once it melts. What do we have that is clear, dries quickly, and readily available?Does anybody else have experience with this?UPDATE: Some relevant links...An ideal result.Parabolic mirrors are another possibility, but I'm still more interested in a lens.Where a lot of this sprang from.Indices of refraction. Is it Indices or Indexes?Hmmm....

Topic by carbon    |  last reply


I saw this yesterday and thought it was pretty COOL...

I went out to the car yesterday at around mid-day and saw what I THOUGHT was the light of the sun refracting off the trunk lid of my car......I WAS WRONG.     I looked up into the nearly cloudless (except in one area) sunny sky, and saw two large clouds "near" each other; with a HUGE bright rainbow in between them. This is the first time I have EVER seen a rainbow in a sunny, rainless, snowless day. Below is a Close up and a normal sized picture of the bow.     In the second picture, there is a speck up there,  that is a crow, IIRC.  

Topic by Goodhart    |  last reply


Using a laser pointer to display secret shapes?

Hey, all, I'm working on a puzzle for an escape room right now and am wondering if there's any way that I can use a laser pointer to display a number. My hope is that the number is not on the lens of the pointer, but rather is discovered after the laser pointer is shined through a specific spot on a piece of plexiglass. The players are asked to set up a tripod in a specific spot with a specific angle, mount the laser point to the top of it and then move the point around the room. Ideally, as the point is traveling around the room, it will shine directly on a small part of a plexiglass display and then refract a number on the wall behind it. Any ideas on how or if this is possible? Any and all thoughts are welcome. Thanks!

Question by DrewP36    |  last reply


How to get the right voltages to make a circuit with laser pointer, LDR and motor?

In short, it is for a uni project, and what I would like to do is shine a light (laser or white light) onto a prism that would have a LDR to detect the light and trigger a motor - the motor is attached to the prism to make it spin and refract the light to the next prism for a chain reaction mechanism to happen (I'd have 3 of them operating in a circle, maybe..) What I really need to know is what types of components to buy as there seems to be different kinds of every one, different voltages. (for example, how strong a laser do I need to be detected by the LDR, etc etc...) Don't want to fry anything! Thank you very much for you help! :)

Question by matisha23    |  last reply


Bottled light in the Philipines

There's a novel, simple idea spreading in the Philipines - using bottles of water as skylights. The concept is staggeringly simple - slum dwellings are dark, and need light, even in the daytime. Though they have electricity, it is the most expensive in the area, so they can't afford to use powered lights. Instead, they use water. A two-litre bottle of water, with a little bleach to prevent algal growth, is set into a section of metal sheeting, which in turn is set into the roofs of dwellings, workshops, even chicken-coops.  The water-bottle refracts the light in all directions, instead of letting it shine through in a single beam, and provides as much illumination as a traditional 60W bulb. OK, so this is old news to some people, but it's new to me. For more information, have a look at the Litre of Light website, or just have a poke around Google and YouTube.

Topic by Kiteman    |  last reply


Things to do with LCD backlight guide plate and polarisation films?

I received about 15 damaged laptop screens and took them apart to get the CCFLs and inverters which I'll combine into a modest spotlight for video recording. From each laptop I also gained some films and the light guide panel. I believe one of the films from each is just a simple diffuser whilst the other two appear to also be blurry polarisers. Finally, each screen has an acrylic light guide which refracts the light 90° and does so evenly by having some kind of bumps or dots spaced out according to the "diffusion equation" so there are more further away from the source of light (which comes from the side).  Any ideas for what I might use these films and plates? I do have a lamp project for which I can use the diffusion film but the polarising films would probably absorb too much of the light.

Topic by THX 1138    |  last reply


Any suggestions for a 5mm - 10mm telescope eyepiece?

I am currently using a home built 3'' refracting telescope, and want to build a shorter focal length eyepiece to get some detail for observing planets (lunar surface, rings on Saturn, more of the moons of Jupiter. The current setup uses a plossl eyepiece with about a 25mm focal length, giving 30 to 40x magnification, and allowing very clear viewing of the moon, and will pick out three of Jupiters moons on a clear night. Ideally I'd like a 5mm to 10mm focal length, for a 100 to 200x magnification. I've considered using the lens out of a DVD drive, which looks as though it could work, although I've only seen one example of it done before. I also have a selection of reasonable quality prisms and lenses about 1'' diameter, with focal lengths from about 2'' to 4''. So, how well would a DVD drive lens work, and are there any interesting designs that make an eyepiece with a focal length significantly shorter than any of its component lenses (in the same way the focal length of a plossl is about 1/2 the focal length of the lenses used). Thanks in advance for any help. (Would this get better response in the photography section)

Topic by The Skinnerz    |  last reply


fishbowl with floating tv

Can someone tell me if this has already been done or where i might find some information? (beg pardon if answer is painfully apparent / easy to find and i didnt) backstory: i bought a house. in historical documents of 1905 a lighted "french" sculpture was mentioned. it is now gone but there is a convenient hole with a electric switch for said hole. i was thinking of what to put in the hole and i remembered watching the Chris Isaak tv show something like ten years ago and aside from the amiable goofball lead the show also had an wise advisor character who was dressed up like a mermaid and through the refractive index of a fishbowl and some other feats of science appeared to be floating and moving in a large fishbowl mounted on a table in a bar. question1; does anyone know the conditions necesary to set up a similar trick? maybe with a small tv, cell phone screen, clock, camera, or something else set up on the bottom of a glass ball with the image floating in the ball? question 2; could you set up a large trapezoidal cube made of glass on top of a flat screen tv on the floor where the light bending quality of the glass would redirect the image on the tv on all the surfaces of the cube? sub-question; could you make said cube with slightly convex surfaces to enlarge the image of a very small image projector?

Topic by brazenfaith  


MAPPING FESTIVAL 2012 /// LINE UP

The Mapping Festival is an international cultural event dedicated to VJing and its neighbouring disciplines, that is to say audiovisual art in the broadest sense of the word. Created in 2005, the Mapping Festival is already in its eighth edition. Year after year, it continues to attract a broader public and to put an emphasis on the most forefront artists while introducing their work and creations built of all kinds of new and innovative technologies. --- You’ve asked for it on Facebook, you’ve desperately looked for it on our website, you’ve even tried to rob us information on Twitter, but there was nothing to do about it, we’ve kept the secret until the very last minute. Less than two months before the eighth edition of the Mapping Festival, taking place this year from May 10th to 20th in Geneva, we’ve finally decided to reveal the line-up. For this 2012 edition, the Mapping Festival remains true to its motto “Visual – Audio & Deviant Electronics” and presents an architectural mapping of the Museum of art and history, takes you on a fairground stall, gives you the opportunity to discover La Gravière, invites you to a Secret Label Party, a new audiovisual label, and make you lose your bearings with such performances as Dieu est un DJ, Loop me or La Caputxeta Galàctica. Want to know more? We’re getting to the heart of it … This year, we’ve decided to unveil our program step by step. You will find below our global line-up, but some focuses will follow, to keep the party going! But let’s not make you languish any longer… Ladies and gentlemen, here is the line-up of the 2012 Mapping Festival: EXHIBITION @ Le Commun – Bâtiment d’art contemporain (BAC) /// from 10 to 20/05 Preview: 10/05 Pascal Dufaux (CA) Déjà vu Joanie Lemercier (AntiVJ/FR) Eyjafjallajokull Daniel Canogar (ES) Scanner Aleksandra Dulic (CA) In a Thousand Drops… Refracted Glances Frederik De Wilde (BE) UMwelt-VIRUtopia Danny Perreault (CA) Flow ARCHITECTURAL MAPPING @ Musée d’art et d’histoire /// 19/05 Bordos.ArtWorks and Invited Artists (HU) Apparati Effimeri (IT) AUDIOVISUAL PERFORMANCES @ Théâtre du Galpon /// Fonderie Kugler /// Cinéma Spoutnik /// Théâtre de l’Usine Insectotropics (ES) La Caputxeta Galàctica Insanë (CA/CH) Dieu est un DJ- 1st representation Sculpture (UK) Unstable Modular Collage Casper Electronics (US) Tasman Richardson (CA) Chloé Tallot + Arnout Hulskamp (FR/NL) Red bus Yilab (TW) Loop Me RYBN (FR) ADM7:FLASHCRASH – 1st representation Michael Vorfeld (DE) Light bulb music TVestroy (CA) FLEETING INSTALLATION Cie Nejma & A-li-ce (FR) La Baraque Foraine 6.1 VISUAL-AUDIO CLUBBING @ Zoo /// La Gravière /// La Fonderie Kugler Discodeine (Kill the DJ/FR) Remain (Meant Records/FR) Vosper (Meant Records/CA) El Hijo De La Cumbia (AR) Nekochan (FR) Label Commercial Suicide Party (UK) Ras Mali (CH) Tempo Moderno (BR/IT) Discotecario Doca et Actaruss1 RomBeads (K.O.E/CH) Monkey Freakz (CH) DMS vs Hiiters (CH) SECRET LABEL PARTY @ Fonderie Kugler /// 12/05 The official launch of a brand new audiovisual label! The best artists of the moment and long-time favorites of the Mapping Festival, all gathered around for a full day of lectures, performances, and of course party. A wild event, keep an eye on them… WORKSHOPS MadMapper (CH/FR) TagTool (UK) And as always, the VJ CONTEST @ Cinéma Spoutnik /// 18-19/05 More info soon… www.mappingfestival.com

Topic by MappingFestival  


History of Printing Mesh

Sit in on a trade show seminar or visit an online forum, and you'll encounter countless debates about the "right" type of mesh to use. The truth is, while there are some guidelines to follow, the best way to determine what's right for your shop is by trial and error. Only problem is, who has the time to experiment? There are literally hundreds of mesh types out there. Trying to choose the best one can seem like an overwhelming task, but by following some general rules of thumb, you can narrow down your mesh choices to a dozen or so. Then testing each kind won't seem so unmanageable. Specs. It may look like the screen on your back door, but screen printing mesh isn't the same kind of material. The biggest difference is that unlike what keeps bugs out of your house, this type of mesh is made from fabric, not wire. For this industry, monofilament polyester is the most frequently used mesh material. When you start shopping for mesh, you'll also need to determine the weave, count, thread diameter and color that's best for your shop. The type of weave is a no-brainer. When researching mesh, you may come upon the terms plain-weave and twill mesh. The difference between the two is how the threads are woven to create the mesh pattern. Make sure you purchase plain-weave mesh instead of twill mesh, which can cause moiré problems, especially in the high mesh counts. Mesh is often referred to by its mesh count – i.e. 120 mesh, 230 mesh etc. – representing the number of threads per inch. The lower the count, the bigger the mesh openings. Low mesh counts are commonly used with specialty inks such as glitter and puff to allow big ink particles to reach the substrate. High mesh counts are mainly used to print fine details and halftones. Printing through high mesh counts also produces a thin layer of ink on the garment, creating a soft hand. Mesh with a count that falls somewhere in the middle is what most screen printers rely on for their basic, everyday print jobs. The last factor you'll need to decide on is thread diameter. Until a few years ago, terms such as S, T and HD were commonly used to refer to thread diameter. Now, however, a more universal method of referring to the diameter number (in microns) helps keep consistency throughout the industry. While there's no standard thread diameter for each mesh count, there's generally a heavy-duty and a light version for each mesh count. The thinner the thread, the better the detail, but the weaker the fabric. The mesh manufacturer or your local distributor will help you weigh the benefits of each and determine what's right for your individual shop. As you shop for mesh, you're sure to come across different colors. Mesh is typically offered in white and yellow, although orange is available from some manufacturers. During exposure, a white mesh will refract the light similar to the way in which a fiber optic cable works. The light travels down and out, affecting edge definition and quality. This isn't as important with lower mesh counts, but when you're doing a lot of fine detail and halftone work, such slight adjustments will show up in the final print. For this reason, many printers stick with white for lower mesh counts, but use yellow or orange for higher mesh counts. Assess Your Need. Everyone has a preferred type, but there are some general guidelines to go by when you're in the market for mesh. Look around your shop and you'll find clues to what type of mesh counts you should be printing with. The three factors to base your decision on are the type of garments you're printing on, your ink type and the kind of frame system that you use on a regular basis. You'll also need to take into account the type of print jobs you typically do. For most screen printers, T-shirts are the order of the day. They can probably get by using a middle-of-the-road mesh count such as a 110 mesh. However, if you print a lot of athletic numbers and use thick ink to withstand the rough treatment jerseys encounter on the field, you'll probably need a coarser mesh count to allow the thicker ink to reach the material. In such cases, it's not necessary to use a high mesh count. On the other hand, if you do a lot of halftone and fine detail work, you'll need a higher mesh count to retain the minute details in the design. Also let your distributor or manufacturer know what type of frame system you use, as some types require sturdier mesh (and higher thread diameters) to withstand repeated use. In general, most screen printers find that a 110 mesh count will work fine for most jobs. The key word here, though, is "most." Don't rely on 110 mesh for each and every single job. Instead, try out different mesh counts with different print jobs, and keep a record of your production results. Note the mesh type, screen tension, type of ink and whether the print job is multicolor, process color, etc. Also note the garment type: Are you printing on a nylon jacket or a cotton T-shirt? Regularly reviewing your records will help you see a pattern, and decide which mesh tends to work best with a particular ink and design combination. You'll be surprised by the varying results between your "everyday" mesh count and one that's a little higher or lower. If you want to experiment with different mesh counts, start with the coarsest mesh and work your way up to the higher numbers, noting how the print looks with each version. Hit the Trail. Most screen printers have an established local distributor that they order supplies from. Others may prefer to order directly from the manufacturer. To find a list of mesh distributors and manufacturers, check out IMPRESSIONS' 2003 Sourcebook. Decoding the Salesspeak. The world of mesh can get a little technical. Here are some key terms to help you navigate the terminology: Low-elongation (LE) mesh – Most monofilament polyester fabrics are low elongation. The term refers to the mesh's ability to retain its tension level. In the past, stretching screens required tensioning the mesh to say, 25 N/cm, letting it relax to a lower tension then repeating the process. Today's low elongation mesh typically only requires one go-around. Monofilament polyester mesh – Some printers who've been around for years still use multifilament polyester mesh. However, the majority of the industry has switched to monofilament. Although it must be abraded for good emulsion adhesion, monofilament mesh tends to stretch, hold tension and print better than multifilament mesh. Plain-weave mesh – Almost all mesh for the textile printing industry is plain weave. The term refers to the method by which the threads are arranged to create the mesh openings. Warp – The threads that run the length of a roll of mesh. Weft – The threads that run the width of a roll of mesh. The Numbers Game. Mesh is typically ordered by the roll, usually in yards. The price depends on the width of the roll (40", 50", 60" wide, etc.), the mesh count and the color. White mesh is not quite as expensive as yellow or orange mesh, because it doesn't go through the dying and rinse processes. Setup Surprises. Be careful how you open the packaging surrounding your new roll of mesh. Avoid using a knife if possible – mesh can be damaged just by being carelessly opened. Once you've opened your new mesh, store it someplace out of the traffic flow. Try hanging it on a wall like a paper towel roll. Getting it up and off the floor can prevent accidental damage. Keeping the roll visible also allows staff to monitor the supply. Don't wait until the last minute to order mesh – you may not be able to get a new supply in time for that next rush job. Care and Feeding. Once you stretch your screens, what can you do to keep the mesh in top shape? For one thing, be careful with your screens. While coarse mesh can withstand more wear and tear, high mesh counts can be easily damaged when moving them around the shop. To extend the life of your mesh, try stretching your screens so that the squeegee stroke runs parallel to the warp. After several print jobs, who can remember what the mesh count is on a particular screen? To help keep confusion to a minimum, consider writing the mesh count number directly on the screens or frame. Or, color code your stock: white for lower mesh counts, yellow for the more detailed work. So while there's no hard rule for what mesh counts to use, knowing what to look for can help you find what's right for your shop. – CW from Internet

Topic by sharefilters