Matte information

[Doug Griffith]

We are in the middle of quoting a very large frosted acrylic order. Around 3500 48" x 96" x .125" sheets. Not a laser job but a fabrication job. I just thought I'd share some non-proprietary information provided by our supplier. You may find it interesting.

"As you know all cast acrylic sheets are produced with glass pairs (as molds). All matte-finish molds are best delivered from Europe, either Pilkington Glass of U.K. , or St. Gobain of France . Delivery of the glass from Europe normally takes 7 months. Both Pilkington and St. Gobain are so overwhelmed by number of matte requests, they both set quantity limits. To make matters worse, each glass set can only be used for about 300 turns, producing less than 300 P95 sheets. So, very costly molds, with long delivery time and with limited quantity and usage, all results in long and costly production of P95 sheets."

[Joe Pelonio]

Is that matte, frosted, or both? I use a lot of matte for signs and noticed the much higher price on it. Frosted didn't seem that bad, though.

[Doug Griffith]

It's frosted with a single-side matte. It sounds like the limited lifespan of the matte molds/glass contributes the higher cost.

[Rodne Gold]

The other option is to use clear pex and to clad it with a frosted/matte vinyl - you get many types and varieties of the vinyl, you can then use much cheaper extruded rasther than cast pex.
Another option is to sand blast clear pex.
In all likelyhood the sandblasting will be cheaper but will show up fingerprints

[Dan Hintz]

I had no idea the molds were limited in their production capabilities (I'm assuming this is just the matte finish, right?). I suppose with enough heat/friction from the poured acrylic the finish would slowly be rubbed smooth, but I never thought too much on it. Why the best molds come from Europe is still a mystery to me, though... the US has some really high-quality manufacturers (DOW Corning Glass Works, for example), though I suppose if they're not interested in making molds...

[Scott Shepherd]

I was at a plastic supplier's location and they had a big box of scrap that they had taken from customers to dispose of safely. In that box was a large piece of acrylic and it had been frosted. I picked it up and looked close at it. It had not been sandblasted and it was not frosted vinyl. I asked him how it was done and he looked at it and said he didn't know either, but he thought it might be a chemical process.

To this day, I've never seen anything that would allow me to do it, but I will say it was outstanding on the quality and uniformity.

If anyone's seen a chemical process for doing it, speak up!

[Dan Hintz]

Steve,

Any reason to believe it wasn't cast that way? They acid etch the glass molds to get the texture.

[Scott Shepherd]

Steve,

Any reason to believe it wasn't cast that way? They acid etch the glass molds to get the texture.

Yes, not cast that way. It was clear with bits frosted on it, large sections frosted. It appeared to be a customer logo specific piece that spanned across several large panels, all put in place by standoffs. Just as an example, it might be 6 pieces, all carrying part of the logo or message, spaced evenly on a wall, to create a mural effect with the brand, logo, message, or whatever it was. I don't recall what was on it, but there were a number of pieces with different things on it that appeared to go together.

I can't recall if it was clear and the letters were etched or the other way around. I think it was the other way around. I think the sheet was frosted all over and then the letters were clear.

[Dan Hintz]

Do you remember how crisp the edges of the logo were? If they weren't ultra crisp, I can imagine flame polishing a textured piece through a tight mask as a possibility...

[Doug Griffith]

The other option is to use clear pex and to clad it with a frosted/matte vinyl - you get many types and varieties of the vinyl, you can then use much cheaper extruded rasther than cast pex.
Another option is to sand blast clear pex.
In all likelyhood the sandblasting will be cheaper but will show up fingerprints

This job is for about 30k units that will be handled a lot and need to be durable. I think vinyl would eventually delam on the edges and applying it to that many units bubble free would be a nightmare. It's just too big of a job for sandblast plus it wouldn't give the quality needed. The units are also going to be digitally imaged. The acrylic alone on this job is upwards of 100k USD!

[Scott Shepherd]

Do you remember how crisp the edges of the logo were? If they weren't ultra crisp, I can imagine flame polishing a textured piece through a tight mask as a possibility...

Dan, very crisp. As if a vinyl mask had been applied and then the sheet etched, then the mask removed. It looked very nice.

[Dan Hintz]

I know they sell a frosting spray... maybe they used that?

[Rodne Gold]

cos of the heat involved in curing the acrylic , the sheets of glass lose temper and bow leading to acrylic sheets with inconsistent thicknesses beyond the normal 10% tolerances for cast. Thats why the moulds "wear"
Degussa have a very nice range of frosted - degussa.de - extruded , enquire of em. They can handle the quantities and extrude it , the rollers have the frosting on em.

[Dan Hintz]

Good to know, Rodney. This means it also happens on smooth stuff, not just the textured. It's likely, then, the 10%+ or so difference seen between off-the-shelf sheets is due to when (in the life of the mold) a sheet was cast, with sheets getting thinner in the middle as the mold wears out. Consistency in thickness would come from either paying a high price (to allow for more frequent purchasing of new molds) or just getting lucky to get sheets from the same general time of life from one mold to the next.

[James Stokes]

I have sandblasted acrylic before and got a very nice even frost.

[Rodne Gold]

The big issue with the manufacturers is the sheet size , if they used smaller thicker sheets of glass , this wouldnt be as big a problem as it is.
They normally turn the sheets of glass over from time to time but all this does is either make the edges or the centres of sheets thicker.
Thats why cast is so bad in terms of thickness variation.