Diffusors: opinions about EPS polystyrene?

[bwo]

Some pics of Optiffusor. Unpainted and painted.

[Jens Eklund]

Originally Posted by hom3r

Has anyone considered coating something like resin on an EPS diffusor before painting? I just built several 2D prds out of EPS and I'm trying to decide whether to simply paint it or do something more fancy.

I’ve tried some different methods and I currently simply apply 2-3 coatings of latex paint but I’ll soon try to mix in some of this stuff in the paint to make the coat even harder:
http://www.casco.se/_upl/pdf/produkt...Fix%203676.pdf

This is apparently common knowledge in the fish-tank DIY community as EPS is often used when making decorations.


I did try using normal filler mixed with paint but it is a bit hard to apply with a brush:
Diffusors: opinions about EPS polystyrene?

[localhost127]

Originally Posted by hom3r

I've been using Owens Corning F-250 in 1" and 1.5" thickness. My local Home Depot carries both in 2'x8' strips. Ive been doing the cuts manually with a straight edge and extra long safety blade. Making each 2'x2' panel takes me 4-5 hours. Here's a pic of two I have completed:.

thanks - ill check my local HD today for OC F-250.

if it comes in 1" thickness, that may prove to be an easy way to hand-cut and make 1D w/ 1" well thickness.

[localhost127]

Originally Posted by bwo

Some pics of Optiffusor. Unpainted and painted.

those look beautiful.
how much does each weigh?

how are you liking the rear wall + rear sidewall boundaries being diffusive, now? i haven't seen an update regarding your room in some time.

[bwo]

Originally Posted by localhost127

those look beautiful.
how much does each weigh?

how are you liking the rear wall + rear sidewall boundaries being diffusive, now? i haven't seen an update regarding your room in some time.

They weigh 3-4 kg each.
The brown colour is looks pretty good, better alive then what the pictures are showing. Tried a lighter brown color, but that ended being more orange like the picture below is showing. I will probably paint them black in the future and use them in a dedicated home theater setup.

Sound is overall much better with the diffusors on the rear sidewalls as well as the one I already had on the rear wall. More engaging and smoother. Haven't had too much time to listen yet though. But the fact that it's more diffucult now to press the stop button when I need to do other stuff, is a good sign.

[hom3r]

Originally Posted by bwo

Some pics of Optiffusor. Unpainted and painted.

Did you procure those from Jens? I haven't seen anything about how to buy an optiffusor, although I would be more inclined to try and build one myself if the geometry for it was publicly available.

[bwo]

Originally Posted by hom3r

Did you procure those from Jens? I haven't seen anything about how to buy an optiffusor, although I would be more inclined to try and build one myself if the geometry for it was publicly available.

Yes. Bought them from Jens.

[localhost127]

team,
my local Lowe's stocks Expanded (EPS) Polystyrene foam. however, upon inspection it doesn't feel very firm or dense...

i noticed another type (Extruded Polystyrene) that is much more dense and solid. here it is on the left (green) vs the EPS on the right (white).
http://img7.imageshack.us/img7/2362/59453231.jpg


http://img823.imageshack.us/img823/2897/1inch.jpg


http://img88.imageshack.us/img88/3286/1specsa.jpg



im thinking about buying some 1" thick sheets to make 3x N23 QRDs (1" well width) out of this. a table saw would be all that is required, and then the well risers could be glued together. i would cut the foam to the required HEIGHT of the well.


would be much quicker to make and far lighter and less costly than a wood QRD. any thoughts on this or the material?

the only issue is, i would not have well dividers unless i were able to find some 1/8" wood or aluminum to use as well dividers...ill keep looking around but any input on the divider-less option re: N23 QRDs?

intent would also be to paint (resin) to harden and protect the foam as well, but from early investigations, it already feels much stronger and denser than the EPS.

[Jens Eklund]

Originally Posted by localhost127

the only issue is, i would not have well dividers unless i were able to find some 1/8" wood or aluminum to use as well dividers...ill keep looking around but any input on the divider-less option re: N23 QRDs?

A QRD without the fins (dividers) is not a QRD and will not perform as predicted.

[localhost127]

Originally Posted by Jens Eklund

A QRD without the fins (dividers) is not a QRD and will not perform as predicted.

that part is understood. ill attempt to find a suitable 1/8" well divider.

Jens,
could you please add any input regarding the material? -or what specific type of paint you use (is it spray paint, painted with brush, etc - what to look for in the stores).

[localhost127]

hmm, it appears i may be mistaken in my assumption of EPS being a single material --- i am not led to believe there are multiple densities of Expanded polystyrene foam? is this correct? if so, does anyone have a recommendation on a particular density for this application? (since i clearly do not have any of the materials in front of me). ...the particular EPS that Lowe's carries is not very dense at all, and with slight pressure you can push your fingers into the foam and dent it. thank you,

[aackthpt]

Originally Posted by localhost127

i am not led to believe there are multiple densities of Expanded polystyrene foam? is this correct? if so, does anyone have a recommendation on a particular density for this application?

EPS can be different densities, regardless of whether we are talking about expanded polystyrene foam or extruded polystyrene foam. The stuff you posted is the expanded variety, while what others have discussed procuring in sheets is the extruded stuff. You need to head to a Home Depot instead - according to their website they stock the OC Foamular F-250 which was recommended earlier in this thread. From its data sheet it is 1.8 pcf which (in other units) is very close to what Jens recommends.

As for your painting question, Jens said he uses latex paint which is ordinary interior water-based paint. He also said he sprays it. It can be sprayed using a variety of different types of equipment. Home Depot or your local tool rental shop can rent you a professional airless sprayer which is probably the best bet.

[localhost127]

Originally Posted by aackthpt

EPS can be different densities, regardless of whether we are talking about expanded polystyrene foam or extruded polystyrene foam. The stuff you posted is the expanded variety, while what others have discussed procuring in sheets is the extruded stuff. You need to head to a Home Depot instead - according to their website they stock the OC Foamular F-250 which was recommended earlier in this thread. From its data sheet it is 1.8 pcf which (in other units) is very close to what Jens recommends.

As for your painting question, Jens said he uses latex paint which is ordinary interior water-based paint. He also said he sprays it. It can be sprayed using a variety of different types of equipment. Home Depot or your local tool rental shop can rent you a professional airless sprayer which is probably the best bet.

thank you -

note above that i did manage to find extruded foam @ lowes (the green panels in my photos) - it was much more dense but i did not see any figures for it. i'll give home depot a try next time i'm in the area. thanks,

[aackthpt]

Originally Posted by localhost127

thank you -
note above that i did manage to find extruded foam @ lowes (the green panels in my photos) - it was much more dense but i did not see any figures for it. i'll give home depot a try next time i'm in the area. thanks,

good point, I missed it. Pactive Greenguard 25psi board's data sheet says directly that it is 1.8 pcf. http://greenguard.pactiv.com/Product...-25PSI-BRD.PDF
It turns out the 40 psi product says it is the same density also.

[localhost127]

Originally Posted by aackthpt

good point, I missed it. Pactive Greenguard 25psi board's data sheet says directly that it is 1.8 pcf. http://greenguard.pactiv.com/Product...-25PSI-BRD.PDF
It turns out the 40 psi product says it is the same density also.

data confirms with what i felt - thanks,

[Ciaccona]

Originally Posted by localhost127

Jens,
could you please add any input regarding the material? -or what specific type of paint you use (is it spray paint, painted with brush, etc - what to look for in the stores).

Any more info on this available?

I'd like to paint some EPS diffusors but I feel like painting with a brush will look crap and spray may eat the diffusor (well, actually I was told this is only the case if you're too close while spraying).

[Jens Eklund]

The easiest way of painting EPS is with a normal wall paint (water based, some thinners might melt the EPS, regardless of distance ; ) either by using a brush, a spray gun (HVLP), or a combination of the two starting with a base paint that covers better, applied with a brush 1 – 2 coatings and then finishing it with a couple of layers with a spray gun (and yes, it´s A LOT faster than using a brush) assuming the gun can handle the paint without thinning it too much. How many layers you need to apply depends on how good it needs to look. If you want a smooth surface that completely covers the EPS texture even if looking close, you might need to apply 4 or more layers. There are other more advanced ways of coating EPS (epoxy etc.) but nothing I would recommend in general.

[bwo]

I have only used brush and it works fine. Doesn't take that much time either. They look good, though the picture isn't great.

[OpusOfTrolls]

My opinion is I hate styrofoam and the thought of it gives me goosebumps. Although the coatings do sound promising.

[Ciaccona]

Originally Posted by Jens Eklund

The easiest way of painting EPS is with a normal wall paint (water based, some thinners might melt the EPS, regardless of distance ; ) either by using a brush, a spray gun (HVLP), or a combination of the two starting with a base paint that covers better, applied with a brush 1 – 2 coatings and then finishing it with a couple of layers with a spray gun (and yes, it´s A LOT faster than using a brush) assuming the gun can handle the paint without thinning it too much. How many layers you need to apply depends on how good it needs to look. If you want a smooth surface that completely covers the EPS texture even if looking close, you might need to apply 4 or more layers. There are other more advanced ways of coating EPS (epoxy etc.) but nothing I would recommend in general.

Thanks for the reply, Jens.

I bought a bottle of white acrylic paint for starters.
Gonna paint it with a brush maybe 2 times, let it dry, and then I'll see if I take spray or brush for colour.
The guy in the shop warned me I'd probably not get a consistent paintjob with a spray can when I showed him a pic of the diffusor.
So let's see how the base coating turns out!

[Ciaccona]

Sry guys, a quick one:

What would be my best choice of weapon to cut a 2'*2' polysterene diffusor in two parts without making a mess of crumbs? Assuming I don't have a sword by Hatori Hanzo handy.

[Jens Eklund]

Originally Posted by Ciaccona

Sry guys, a quick one:

What would be my best choice of weapon to cut a 2'*2' polysterene diffusor in two parts without making a mess of crumbs? Assuming I don't have a sword by Hatori Hanzo handy.

Hot wire or a hot knife.

[Glenn Kuras]

Originally Posted by bwo

I have only used brush and it works fine. Doesn't take that much time either. They look good, though the picture isn't great.

+1... Have tried it all kinds of ways but a brush with a roller seems to go quick and looks great.

[Ciaccona]

Just to report back for anyone reading up on this in the future.

I've started to (I know, this sounds silly but wait...) paint one 2'*2' EPS diffusor.

First, I applied two "coats" white acrylic paint with a thick brush to get a foundation for the coloured paint.
Unfortunately, the polystyrene sucked loads of the paint, so that the polystyrene-structure still comes through. A little better, though.
1 bottle (750 ml) white acrylic paint = EUR 8,-

So I continued with coloured acrylic spray paint, spraying with a can.
Turns out 1 diffusor needs 4 cans (150 ml) to get 1 coat. (!)
I had to get as close as about 1-2'' when spraying so that the paint would really attach to the polysterene. I did spray a thick coat, though.
However, after drying I find that the material feels a lot harder now (which I guess is not bad for reflection duties) but you can still sense the polysterene beneath the paint.
4 * 150 ml = 4 * EUR 7,- = EUR 28,-

I may be going for another spray coating...
Wait, I have to do another 3 diffusors...

This is expensive!

I got one bag of cement/filling paste.
Thinking about doing a coat with a spatula for the next one to get rid of the polysterene structure in the first place.
Anything wrong with that?

[Jens Eklund]

If you want the texture of EPS to be completely covered; prepare to add at least 3-4 coatings of paint (and I´m not talking about spray paint in a can …). Use normal wall paint that covers well (like latex paint). If you want to spray it on, you need a HVLP gun with a suitable nozzle and with enough power to handle the paint without thinning it too much. Once you´ve got the texture covered, you can experiment with different finishes.

I have done some experiments with fine grain filler mixed in the paint, but the extra time it takes to apply it eliminates possible benefits. It´s quicker to just add 1-2 extra layers of normal paint.

[Ciaccona]

Thx Jens, you convinced me to go a different route now.

I'm gonna get one of those guns, maybe something like that:

Paint Maxx Premium Sprühpistole Farbsprühsystem HVLP Lackierset | eBay

I guess one could easily spend a lot more for a solid gun but oh well...

I understand those guns can be filled with usual wall paint?

What do you think about covering the structure with cement in the first place?
Is that even an option with polystyrene?

[buzzy]

Originally Posted by Ciaccona

What do you think about covering the structure with cement in the first place?
Is that even an option with polystyrene?

That I can answer but, I will not be able to tell how would it affect the response of the diffuser... Polystyrene and cement is used commonly for bathroom building and/or exterior walls isolation, there is an specific cement used over the polystyrene and then tales or exterior paint... Just fixed the whole bathroom in my house at the start of the summer.

[Ciaccona]

Hi buzzy, thanks for the heads up!

I got some mortar suitable for the material but when slapping it on the diffusor I soon gave up. It was a PITA to get a good even surface with all the corners etc.
I got some proper wallpaint, wait for the spraygun to arrive and gonna go mad with that!

[Jens Eklund]

Originally Posted by Ciaccona

I got some mortar suitable for the material but when slapping it on the diffusor I soon gave up. It was a PITA to get a good even surface with all the corners etc.

Originally Posted by Jens Eklund

I have done some experiments with fine grain filler mixed in the paint, but the extra time it takes to apply it eliminates possible benefits. It´s quicker to just add 1-2 extra layers of normal paint.

... told you ...

Originally Posted by Ciaccona

I got some proper wallpaint, wait for the spraygun to arrive and gonna go mad with that!

Make sure that the spray gun can handle the paint you intend to use. The gun you´ve linked to seems unrealistically inexpensive to be able to handle normal latex wall paint. If it does; please let me know.

[Ciaccona]

Ok, progress.

I got some water based wall paint and a spray gun.

This one: Wagner W 95 Handspritzpistole im OBI Online-Shop


Since I live in a flat right in the middle of a city I don't have a garden, so I wrapped the balcony in plastic until it looked like a kill room by Dexter Morgan.

The gun is loud. I mean, it's like a lawnmower. It was so embarrassing I decided trying to do it inside...
Luckily my girlfriend is out of town this week so I set up a kind of box right in the living room. I've attached a pic so that you can have a laugh.

It worked pretty well, I added a bit of water to the paint and the gun would handle it fine.
2,5 l of paint would be enough for 2 rounds for 4 diffusors (2'*2').
The 2 diffusors I painted with white paint before turned out with a smoother surface, you can still see the structure on the other ones.
Also, the "terracotta" brown colour tone turned out to be more of a diarrhea than terracotta.

I'll probably get another more shiny latex kind of paint and repeat until the surface is smooth.

Pics attached.