Not all of them are solid, but yet another detail to watch for.
Phil
The bigger floral spheres are (allmost) all hollow in the Netherlands.
Offcourse it would be better if you can find them in the US.
If it saves everybody a lot of money and it’s the only option to make it a good and both budget BLF IS, I’m happy to help out.
The floral stuff is usually green. If it’s legit anyway. I have a friend that owns a flower shop.
What you refer to we call oase/oasis or “steekschuim”. Haha, and you definately don’t want to use that!
These white balls are styrofoam/styropor/tempex, very different material, but allso sold & used for decorations. But how you find out if it’s dense enough for an IS, I don’t know.
These 12” OD “Smoothfoam” spheres from Dick Blick look promising but I have no knowledge of what the desirable material qualities should for an integrating sphere. So how suitable “smoothfoam” would be… I don’t know.
I do think the indexing keys could be more robust though.
Price drops to $7.67 per half above 12 pcs.
“Smoothfoam Crafter’s Foam is a Styrofoam alternative that is rapidly growing in popularity among crafters. It is a non-porous, expanded polystyrene (EPS) foam that’s harder, smoother, and more durable than traditional Styrofoam.”
Here’s the link
Yep, Oasis. My Mom used a lot of that for floral arrangements. You can shove a soft flower stem through it so yah, not good.
Nice find KFF! That looks like a good one that would hold up to some extended usage. $15.34 for a 12” , sounds reasonable to me!
Edit: The manufacturer, Smoothfoam, says it has 7/8” wall thickness. They sell em for $20 a ball retail with free shipping over $50. Perhaps a bulk purchase could be made?
Edit II: They also do flat rate shipping, one ball anywhere in the US for $4.95. 
So $25 for a 12” ball with 7/8” thick walls for any of us in the US to buy direct from the manufacturer.
That’s the same half sphere sold by JoAnn Fabrics for $9.99 (if you have a local store - not sure their shipping). It was on sale for $7.99 when I bought them (showed cashier webpage cuz they rang up $9.99). I have pics & measurements of it in my Photobucket gallery. Some of the pics are showing sanded vs. unsanded surface.
-Garry
Garybunk,
That’s the same sphere that I was going to purchase before I read this thread.
Sure it would have been simple to build a sphere myself but I would always question it’s accuracy.
JoshK presents himself as capable of producing a consistent product with close to accurate numbers. If enough people purchase them, it could become the de facto low budget BLF standard.
JoshK could probably buy directly from Smooth Foam through his company and get much better bulk pricing. I work a lot of good deals for my company that nobody gets just walking in off of the street. We do need to give him a better idea of how many people would be committed to buy.
I’m In for one.
Wouldn’t the inside need to be fully painted with latex white paint with 3 extra shots of titanium? I’m afraid there would just be too much absorption into the Styrofoam without it.
Or, do I have no idea what I’m talking about? Sure seems like there would be absorption of light though, oh well… Carry on…
Just a thought, but maybe look into something other than Styrofoam? There are aluminum ball baking molds, plastic/fiberglass decorative concrete ball molds, bowling ball molds, spherical candle molds, aluminum 2-piece spheres (architectural/lawn ornaments, etc.), and probably a few other possibilities.
Prices might be a tad higher, but might be tolerable. For instance, I’ve seen the 2-piece aluminum baking mold for under $5 shipped, and it comes with a a ring-stand (however, I think it’s only 6.5” in diameter). I also like the idea of a 2-piece design. Just have to come up with a good method for attaching the 2 halves. That would give you easy access to the internals, which may come in handy (most IS designs I’ve seen are open-able). It would also allow for a smaller shipping dimension for the finished product. The end-user would just need to assemble the 2 halves.
Plus, Al or plastic/fiberglass would be much less fragile than Styrofoam, and the outer diameter wouldn’t be as large. The smoother internal surface might be better and easier to paint/coat as well. Any attachments (light meter mount, etc.) would be more sturdy/secure I would think too.
I think djozz has pointed out that the styrofoam can allow light passage and this gives room for high output lights to be measure through the sphere, meter on the outside, but I might have misunderstood.
Isn’t this where the internal baffle comes into play? It is my understanding that you want the meter shielded from the line-of-sight of where the light beam first “hits” (hot-spot).
Something like this:
Also regarding the internal coating:
You can get a pound (500g) of barium-sulfate powder for around $15US. If you mix that 50/50 with pure white latex paint, it would give you a very good reflective coating that is relatively durable.
Oh I’m not suggesting not to proceed with JoshK’s plan. I’m all for it. I was just stating that the Smoothfoam is the one I have and I have pics & measurements on it.
I can say this about the Smoothfoam one, little if any light comes in from the outside. This is without painting inside or outside. I put mine on the floor directly under a “60w equivalent” CFL bulb and saw little to no lux increase on my meter (when blocking the entrance hole).
-Garry
There’s a LOT more to IS’s than meets the eye, and there is a LOT of wisdom and experience on the subject here on BLF threads. You will do well to read about and understand what you can expect from a device like this- it is not going to be accurate with every light at every lumen level. It will still be very useful to most of us, especially modders. Given careful proper construction of the IS, an accurate meter, matching of a light to sphere size, matching of tint to the calibration standard and light sensor, and with correct measuring technique you might reach 90% to 95% accuracy, but it is not uncommon to see a 20% variation when you stretch those parameters even slightly. This kind of sphere will be useful, fun, and normally somewhat accurate in that order. Don’t expect more unless you want to spend multiple thousands of dollars to get it.
Where it will be most useful is with comparison between mods you’re doing and between other members testing the exact same light in the exact same manner as you do. I think I know what 900 lumens looks like based on readings others have reported and some of the lights I own which they reported on. But I could also be basing that on what could be substandard lights in my stable and I’d never know it without something like this to alert me of that variation, so even for non-modders it can be useful. Just don’t expect to get what you’re not paying for.
I think this will be a good deal for those who have not already built their own sphere. I think it’s biggest virtue will be it’s being set to a standard along with the other spheres like it which will allow for better comparisons between members who are in distant locations. The few who have already built spheres and shared their light source standards with each other to cross-check calibration have something like this going for them- now the average person will be able to have that too.
Phil
Unfortunately, flat rate shipping does not apply to Hawaii or Alaska. :cry:
$6.50 here
Barium sulfate
It loses its effectiveness of you mix it into the paint. Better to dust it over the wet paint. Come to think of it, I probably have a bagful in my pyrotechnic supplies. It makes a nice green.
The cheapest I’ve found is about $15/lb. shipped. The problem I think is that shipping is usually quite high (hazmat?). For instance, the link above puts it at almost $20 after shipping.
Besides the cost, I think the primary benefit of mixing it in with paint is durability. Without any filler/binder, it dries into a flaky powder which will easily be brushed off.
I suppose if you time it right and dust it onto wet paint, that might hold up OK. Probably have to experiment with it a bit. 
Freefly, make sure you have some numbers with the ‘very good reflective coating’ statement.
Killforfood, I read about the ‘dust over wet paint’ method, but it was not checked for effectiveness. In fact, BaSO4 layers are fairly transparant, letting light in deep inside the layer, so you need far more than a ‘dust thin’ layer of it.
In general, there are quite a few ideas about DIY reflective coatings out there, and there are more beliefs than tested results (because testing a coating for equal reflectiveness for the whole visible spectrum is not trivial). I have not come across any source that showed that any DIY coating is better than sanded bare styrofoam, and a few pilot tests that I did on BaSO4/latex paint mixtures did not show any advantage. Making the coating did show however that it is a pain to apply, is sensitive for cracks, and it reduces the reflectiveness of the sphere (which is not neccessarily a main problem for the workings of the sphere btw)
In the context of a DIY “budget” IS that is not going to be a highly sensitive, perfectly calibrated tool, I think it’s a safe assumption that pure white latex paint with BaSO4 added would provide adequate reflectivity, and is actually quite good (it’s a well-known trick as a projector-screen wall treatment in the DIY Home Theater world as well). If there are better alternatives (besides the costly IS coatings like Spectralon, etc.), then please share!
I personally don’t have any numbers/data, but here is a test that was performed by students at a Utah State University lab (opens a .pdf document): Barium Sulphate And White Paint Testing
I would also be surprised if bare Styrofoam performed just as good. A good reflective surface/coating reflects light. If you shine a light inside of a bare Styrofoam ball, it will let quite a bit of light through. So maybe I am wrong, but I would think that light you see “glowing” on the outside is light that is not being reflected/integrated inside the sphere?