I’ve just been handed a new problem at work. One of our projects which I’ve mentioned previously is a Visitors Center in Coldfoot, Alaska for the BLM. We’re doing a bunch of custom casework out of solid and ply Baltic Birch with some Yellow Birch solid stock being used in one room to match the existing Yellow Birch flooring. There’s also quite a bit of diarama work being done by a subcontractor (a former employee of our’s) at our facility.
Anyway… for this one inset portion of one of the diaramas is supposed to replicate the underground burrows of some creature called a Vole. I presume it’s related to the Mole. What the Project Manager envisions is something that looks akin to one of those Ant Farm things that have an inch of dirt sandwiched between two panes of glass. This diarama display would only show one side, unlike the two-sided ant farms. Thing is…. there are stuffed animals going into this thing and visitors gotta be able to see what’s in there. So… filling it with dirt is not an option.
My task is to back paint the tempered glass to replicate the color of the dirt part of the diarama just above the glass. (Envision a hillside where part of it is cut away so that you can see underground where the Voles live) The problem facing me is that I don’t know of any paint that will adhere to a shiny glass surface. This same pane of glass is going to recieve some screen-printed verbage before I get it. So, sandblasting the backside isn’t an option either.
One of the other Project Managers at work told me that he’s heard of some sort of acid-etching paint that will adhere to glass. But, he doesn’t know a brand or anything beyond that brief description. Apparently he heard about it a few years ago and the details are sketchy in his memory.
Anyone here heard of a product that might work on glass? Keep in mind that this has to be backpainted, sorta like how a mirror is silvered on the backside… meaning that I can’t rely on a primer to achieve adhesion. Also, this has to be an opaque paint. I did a Google on “Glass Paint” and got a ton of hits for all sorts of faux stained glass stuff. But, that’s all transparent colors and won’t work for this.
An alternative idea that might be doable would be some substance that could be used to sorta glue dirt and pebbles onto the backside of this glass. That would actually look a lot more realistic. But, here again there is the issue of adhesion that we are concerned with.
Any thoughts/suggestions/ideas would be greatly appreciated.
Regards,
Kevin
Replies
Lots of retail stores and offices (the old downtown type) have lettering painted on them. I would try asking sign painters and glass suppliers. The product definitely exists.
Yeah, the store window paints occurred to us right away. Thing is... that paint is chosen for that primarily because you can literally wipe it off. We want something more durable than that.
Regards,
Kevin
Kevin,
The glass surfaces you need to paint will never get any wear and tear being on the inside so I don't think it's as big a problem as you might think. I would visit your local Sherwin Williams paint store and let them figure it out for you. I'm sure they will be able to recommend a product that will do what you need done (pretty sure any way).
Good luck!
Mac
Mac,
The lack of wear and tear is a valid point that I have thought about. Here's my concern there... Coldfoot, Alaska is inside the Arctic Circle. This visitor's center is in an unheated building that will only be used in the more temperate months. The BLM tells us that the temperate swing in Coldfoot is between -80 (F) to 80 (F). To complicate matters, being the greedy capitalists that we are... we've signed a side deal of sorts to warranty our work for 5 years. In more normal environments that wouldnt' be such an unusual situation. But, none of the paint manufactorers will even come close to a warranty of their products in that extreme of an environment. I'm using Sherwin Williams catalyzed vinyl to finish the Birch casework and DuPont acrylic black lacquer on the steel handrails. At any rate... given the extreme conditions, I'm unsure how much the glass will move in the temperature swings. If it moves much and there isn't very good adhesion with the paint... it's a matter of time before the paint will begin to peel. I've never had to paint glass before. So, I'm unsure how much credence to give the adhesion issue in this situation. I'd prefer to err on the side of caution, though.
Regards,
Kevin
Ther's a Portland Or. artist, Gregory Grenon ,who has been painting on the backside of glass for years . He used to be represented by the Laura Russo gallery in Portland. Try getting to him through the gallery. Permanance would seem to be a concern in as much as someone paying top dollar for one of his pieces would want it to be around for a while. Also try Bullseye Glass,also in Portland. They deal mostly in hot glass but might have some leads for you. For that matter you might even try Cline glass they deal primatily in stained glass but here again you might get some imput. Either one of these places might be able to address questions about the temperature extremes. My better half is a fused glass and blown glass artist she might have some imput but shes already tucked away in bed.
Edited 9/10/2003 12:51:33 AM ET by woodnthoughts
Great suggestion! The Laura Russo Gallery certainly is known to me. They're one of the best known local art galleries.
I'd be interested in your better half's thoughts too. She obviously knows the substrait and that's my main need right now. In particular, I would be interested in her thoughts on how much movement, in rough terms, one should expect from tempered glass in that wide of a temperature swing. If the movement is really minimal, I'll be a lot less concerned with adhesion for the reasons that Mac pointed out. On the glass itself... I don't believe it is safety glass, just tempered. And it's standard 1/8" thickness or whatever standard window glass thickness is. The opening is 22" x 53.5"
Thanks for the feedback!
Regards,
Kevin
According to my better half if the glass manufacturer did his job the glass wouldnt be affected by the temperature extremes. her day job is manufacturing sheet glass and other types of glass used by artists and the're very carefull in making sure the sheet glass is free of potential stress problems. If its manufactured properly there would be no movement.
Thanks! That's good to know should I ever be faced with having to paint glass again.
Regards,
Kevin
I'm going to have to disagree here, all glass no matter how it is made, expands and contracts, for that matter everything in the universe expands and contracts with temperature changes.
Properly made sheet glass will be stress free so that it doesn't break with wide temperature swings but it will still expand and contract. Certain glass types, Pyrex for instance, are especially stable and have low coefficients of expansion but all glass expands and contracts somewhat.
Whether or not the movement of the glass will affect paint adhesion is a different matter.
Most plastics have large expansion factors which needs to be taken into account when using plastic to replace glass as a glazing.
John W.
Kev, Signpainter's supply. Years ago I bought some in a wholesale sign painter supply store.They have the correct paint brushes and books of goldleaf dtencils and pounces.
I would look in the phone books under wholesale suppliers. Incidently. unlike the stuff they use on halloween window decorations, (Tempora) it definitly does not wipe off and lasts for years. I believe it's used on the backing for mirrors as well. Stein
I'll look into the Signpainter's supply. I figured sign painter's would know of a product that would work. But, I was unsure of where to find objective info. A friend suggested calling local sign painting companies. But, they would have no reason to give the info to me since that would represent a loss of potential business. As it is we've already taken business away from one local sign painting company on some small POP metal signage for a bank.
Thanks for the suggestion!
Regards,
Kevin
Kev, Czech this out... http://www.pacificcoastsignsupply.com/catolog.htm
Edited 9/10/2003 3:07:01 PM ET by steinmetz
You might experiment with "water glass". I forget it's chemical makeup, but I've used it to stick sand to various materials. You might find it in a store that caters to farmers and the like as it is (was) used to preserve eggs. Interesting project.
I found that site earlier. That's where I found the airbrush paint that I mentioned earlier.
Regards,
Kevin
Kevin,
I have been using a paint called "Breakthrough" that I think would work for you. It has amazing adhesion and is reccommended for painting over tile and most any other surface. I am sure that NO ONE is going to tell you that their stuff will hold up in such extreme environments as you describe because they have no experience to judge that by. I do think a lot of this paint though and I think it is a good bet for your project. Catalyzed acrylics such as are used to refinish bathtubs would also be a good bet. Maybe you could get a local tub refinisher to spray them for you? That would save you the trouble of having all the right safety and spray equipment.
Thanks, Clay.
I hadn't thought of the bathtub finishes. Those most likely are adhered to a rougher surface than glass, though. I do have a full-blown commercial paint shop at my disposal here... 40' wide double spray booth (two 20' booths sandwiched together), air makeup unit on the roof supplying filtered, temperature controlled air, tons of spray equipment. Although... given that this is to be backpainted, low tech would work just as well for me as spraying would since there'd be no way to discern the difference thru the glass. In fact low tech would be easier since I wouldn't have to do any masking.
I'll check out the "Breakthrough" product.
Many thanks for the feedback!
Regards,
Kevin
Just a thought here (and BTW I have no clue how this would work in area with temperature extremes) - Sign companies do all kinds of fantastic work where the window signs are actuallly printed with adhesive on the back of the letters and then another film with a less permanent adhesive holds the whole thing together. The whole thing is lined up and adhered to the glass and then the back piece is peeled off. I have that type sign here in the bookstore where I work at the Univ of TN and what remains on the glass is really quite durable (it's more like an adhered vinyl type letter) PLUS since it's computer generated you could probably have an actual "picture" of the underground vole "system" created for the sign. They generally do these in panels and then the panels are lined up much like you would wallpaper. Since it's only going to be seen from what side - what's on the other side - is there an air space that is likely to generate condensation with the temperature changes or is it an area that could be "dehumidified"??It's football time in Tennessee! Go Vols!!!!
It's not so much the thermal expansion of the glass, but the difference between the thermal expansion of the glass and the paint. If the thermal expansion of the paint is closer to glass than, say, steel, there will be less stress in the paint film on glass than steel. However, the adhesion of the paint to the substrate is much more important.
Here are some coeficients of thermal expansion, per °F:
A 100 inch long piece of glass would expand a little over 1/16 inch between -80 and +80°F.
What does this all mean? To paint glass, buy glass paint.
How about making the mask out of something like Masonite, rather than adhering something to the glass. Masonite looks like dirt.
How about making the mask out of something like Masonite, rather than adhering something to the glass. Masonite looks like dirt.
I was informed an hour or so ago that the powers that be have decided to do something very similiar to what you've suggested. Except that instead of Masonite, which does have a nice brown color, they're gonna use Sintra... which is an expanded PVC product that comes in 4x8 and 5x10 sheets in varying thicknesses and is used widely as a substrait for vinyl graphics signage in internal settings. I'm going to paint it to match the dirt color. All in all this is a much better idea than backpainting the glass. For one thing, backpainting glass is never, ever gonna look like dirt. And then there's the adhesion issue. Although, I did find an airbrush paint that is supposed to stick to virtually anything, even in outdoor applications.
Thanks to everyone who has pitched in with great ideas and suggestions here!
Regards,
Kevin
Sintra is easy to work with. Being, I believe, a PVC product, the thermal expansion is high, so allow a small gap on the top and sides. Actually, since you are going to work it near the high temperature end of your range, it will shrink alot if you take it down to -80°, so be sure it won't fall out of it's mounting if it shrinks. The vendor can give you the coeficient of thermal expansion so you can calculate the shrinkage if you want.
It will eventually sag if stood on edge, so you should support it so it doesn't sag away from the glass.
Sintra comes in various colors. They might have the color you want so you might not have to paint it.
Thanks for the info, Wayne. We actually work with Sintra all the time. I paint it fairly frequently since the manufactorer's selection of colors is very limited. I use DuPont Chromabase, catalyzed, on it and have never had any failures since it is flex-rated if catalyzed.
The mounting issues will be dealt with by greater minds than mine. They don't really care what my thoughts are on that. LOL I'm here to finish wood and paint whatever they put in front of me. In general they don't seem to appreciate my throwing suggestions in on other issues since that is perceived (I presume) as a challange to their competence. That's the downside of working in such a highly specialized part of the domestic economy. You gotta know more than a little to get a job here. Hence, most folks in this biz consider themselves to be experts, more or less, about whatever it is that they were hired to do. I'm no exception, of course. <G>
Thanks again for the info.
Regards,
Kevin
As an addendum... I ended up related what you'd posted here with the Shop Foreman. I dunno if he'll follow up with the Project Manager about the mounting issue you brought up. But, one of the other Project Managers came into the Foreman's office while we were talking and he strongly dittoed your concerns about the expansion and contraction of Sintra under those conditions. Frankly, it's an issue that I had never considered before. I didn't realize that Sintra was that unstable. That's good to know 'cause the stability of the substrait is always pertinent to painting. So, I learned something new today. And that always makes my day. Thanks! :-)
Regards,
Kevin
Thanks for the feedback. It's good the foreman knows the issues, so he can make a decision knowing the facts.
I'm not sure "unstable" is precisely the right description. It's just that PVC, like all plastics, has a high coeficient of thermal expansion, but it's movement is entirely predictable.
To woodnthoughts, there isn't any need to worrry about commercial float glass being made properly. True, glass is sensitive to residual internal stress, and handmade glass, subject to inconsistent conditions, can be formed with residual stress. However, commercial float glass is manufactured under precisely the conditions so as to not produce stress. It's fully annealed and as stable as can be. Like all materials it will expand and contract with temperature, but will do so uniformly, maintaining it's shape and flatness.
I'm not sure "unstable" is precisely the right description. It's just that PVC, like all plastics, has a high coeficient of thermal expansion, but it's movement is entirely predictable.
It's also hydroscopic (absorbs moisture) somewhat akin to the way wood is hydroscopic, right? That would induce a certain amount of movement above and beyond that associated with thermal conditions, n'est pas?
Regards,
Kevin
Solid PVC does not absorb moisture (otherwise PVC water pipe would swell up). Since Sintra is a foamed product, it might, but I would be suprised if it did.
Here's the website of the Sintra manufacturer.
http://www.alusuisse-comp.com/tech.html
Solid PVC does not absorb moisture (otherwise PVC water pipe would swell up).
You would think so, yes. But, people make fish tanks out of plexiglass and it's hydroscopic.
Thanks for the link.
Regards,
Kevin
Wow, the breadth of knowledge in this group is incredible! I'm clueless about all the window-treatment stuff, but had to respond to: "some creature called a Vole. I presume it's related to the Mole." My kitty presents as offerings two or three of these a day during the summer, caught in our field. They are the size of a small mouse, and have long pointy noses and very squinty eyes.
OK, back to my corner.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
LOL it's funny that you should relate your knowledge of Voles in the context that you did. The specs that we received from the design firm in Seattle describes this particular display, which includes a stuffed Lynx that is in "pounce" mode, as "Lynx lunch meat." <G>
The part with the glass is supposed to show their burrow underground, while the Lynx is supposed to be patiently waiting up top for one of the Voles to pop it's head out and become his lunch. LOL
Regards,
Kevin
Kevin,
Painting on the glass has numerous technical and appearance problems especially in the environment that this project has to survive. I'd be looking to create the soil texture on a separate panel that could be placed against the inside of the glass. This would allow you far more leeway to create a realistic surface and will be much simpler to repair or service if needed later.
I realize that you are probably far from a metropolitan area, but, if possible, go to or at least talk with the people who create the displays at science museums, they probably solved all this stuff years ago.
Good luck, John W.
John,
My workplace is in Portland, Oregon. So, I am in a metro area. The kind of stuff that you'd see in a science museum is actually the sort of thing that we build. I suspect that the issue with this particular job was $$$. The Project Manager was looking for a cheap and easy way to get the approximate look without having to pay the subcontractor lady, who is a real Pro with simulating natural things for displays. Yesterday morning her helper brought in this collection of PVC pipes all stuck together at odd angles. By the time I went home it looked like a real piece of drift wood that had been tossed around in a river for a couple years. It's truly amazing what she can do. But.... she doesn't do anything for free. <G> Which I suspect is why the PM wanted a cheaper option since he's the one who has to answer to the big shots about profit/loss issues with this job.
Regards,
Kevin
Kevin,
Kinda surprised no one has mentioned the hobby/craft shops (Hobby Lobby, etc.) They sell a paint specifically for painting on glass. Only hitch is it must be heated in an oven for an hour or so after painting. I have done this in the past, painting images on glasses, and they withstand dishwasher abuse after the oven treatment.
BJ
Kevin,
I work in the architectural glass and metal business. A fancy name for commercial/industrial/institutional glazing projects. Silicone based paint is often used when a back painted glass is required. The people who produce this are geared for production runs of thousands of square feet at a time so buying from them is next to impossible, however, I think that any coloured silicone adhesive applied thinly and evenly would do the same thing.
Silicone based, huh? Interesting...
Thanks for the tip.
Regards,
Kevin
You may have already decided how to go about this, but I thought I'd throw in my two cents.
I work in Stained Glass now and then and have done some work including a substance sandwiched between two pieces of glass and included in the final product. Depending on how large this piece is... If you take one piece of glass and place it on the table and throw some dirt on it. Then take the second piece of glass and put it on top, then use thick copper foil tape to attach the pieces around the edges. Put the tempered glass on the outside and you have a window of dirt. Holes can be sawn out of the two pieces of glass and again covered with copper foil to allow the animals to be placed "under ground."
Good Luck,
Adam
[email protected]
That certain sounds doable, and I think that something using real dirt would be the most realistic. But, the Project Manager wants to do this on the cheap and has decided to have me paint Sintra which will be mounted behind the glass.
Thanks for the feedback. It is appreciated.
Regards,
Kevin
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