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I've been shopping around and no one near me will do Argon filled double pane and only one place will do a vacuum. The price seemed astronomically high considering I can buy the glass and the local hardware store (single pane 2x amount to make double pane) for ~1/10 of the cost. So ranting aside, what is the best way to make double pane glass / window inserts from single pane glass? I was thinking about using something easy like a few 1/4" plastic tile spacers to keep a uniform spacing with weight or light clamp then applying heavy silicone bead to everywhere but the spacers, coming back later to fill in all but one or two of the spacer holes. Do a good inspection and cleaning if necessary, plug to have one hole left and then pulling a vacuum to ~7-10psi (~5 psi vacuum from ambient). Last hole (vacuum hole) will have to be plugged/corked with something else then silicone to ensure longevity.

My project calls for 24 ~8.5"x11" inserts, trying to weigh in my approx. time to build these and that I already have vacuum pump, I could have a 50% success rate and still save money so if it at all possible to do this at home/shop I'm going with that option.

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Unless you're experienced in manufacturing and actually machine the spacer from a material that matches glass expansion and a sealant that will work for at least ten years, it's a total waste of time. The cobble method proposed is going to be a highly frustrating wheel reinvention attempt of an early design that was abandoned. –  Fiasco Labs Mar 7 '13 at 16:53
@FiascoLabs, the spacers are going to be removed hence I'm filling in the holes they leave behind. –  Jason Mar 7 '13 at 16:54
In all the dual-pane windows I've worked with, the spacer is a permanent part of the installation. That is the professional way, and attention to that detail and the adhesive used determines success or failure. Silicone caulk isn't a structural material suited to be a glass separator. –  Fiasco Labs Mar 7 '13 at 18:11
1/4" spacing is too narrow. Optimum spacing for double panes usually runs about 0.5" ->… –  Wayfaring Stranger Mar 7 '13 at 19:13
@WayfaringStranger, thanks. Using this link is shows it off for argon gas, I'm also planning on using thinner glass (I failed to mention). This study shows that after ~3/8" then change is near negligible in comparison to the drastic difference before it. I have the physical constraints of the existing window frame to deal with so I'll bump it up to a 3/8" or .4" spacer only. –  Jason Mar 7 '13 at 21:26

11 Answers 11

Glazing manufacturers have spent decades perfecting a spacer system that does not eventually leak and condense. They still haven't completely perfected it, though they are much better than 20 years ago. There is no way you're going to put together a system that does not eventually leak, especially with a vacuum. You'll have a better chance with inert gas, but I'm not convinced even professional argon filled glazing stays argon filled years later. It's not that I doubt your fabrication skills, it's just that it's a very difficult problem to address.

For all the time and effort spent assembling a window system, it's worth buying professionally built glazing units. If you want to save some money, forgo the argon filled and simply get dual glazed units with a low-E coating. IMO, these offer decent thermal performance and good value.

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+1 for the argon remark, professional fabrication of an Argon IG unit is generally done cost effectively by creating a regular unit and drilling two holes. Argon is pumped into the inlet and the air is pushed out the outlet until an argon detector reaches it's limit. These holes are then filled with a sealant and become the weakest point of the unit and generally have leaks over time. The best units I have seen as far as seal quality are the old Andersen units where the seal is made by the glass itself (no longer manufactured). –  Steve Buzonas Jan 12 '14 at 6:40

You're effectively trying to create a hermetic seal. I would suggest doing a little permeability research for starters. Holding a vacuum short term is no problem but when you have 5-10 years for gasses to seep or diffuse through, permeability rates are very important.

A quick search on silicone:

"They have high gas permeability: at room temperature (25 °C), the permeability of silicone rubber for such gases as oxygen is approximately 400 times[citation needed] that of butyl rubber, making silicone useful for medical applications in which increased aeration is desired. Consequently, silicone rubbers cannot be used where gas-tight seals are necessary."

While glass is hermetic many materials are not. You're going to need to be cautious about what you use for a sealer if you want your double panes to last. Again I would suggest capitalizing on all the research that has been done by scientist on how to form a hermetic seal. They have a variety of techniques that are considered quite effective.

Good Luck

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I would look for a supplier that would ship you the bare panes and build the frames yourself. I doubt you could manage a proper seal. Look how many tries Edison went through developing a vacuum light bulb. Although, even just air insulated double glass would be better than single pane. Unless it stays sealed, condensation will be a problem

You may have to order thermal panes from a glass shop, who then gets them from a manufacturer, Should still be cheaper than buying complete replacement windows.

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I've been pondering investigating this myself, for the window frames which are still in good condition. I'm not sure it would actually be a lot cheaper than a full replacement, but since I'm going to have to reglaze at some point anyway... –  keshlam Nov 19 '14 at 14:24

It's possible to make them yourself if you get the right materials. For spacers search in Amazon for "Dual Seal Aluminum Spacer".

For the sealer use a PIB Primary seal tape that wraps around the top, outside edge, and bottom of the spacer. Search in Amazon for "CRL Polyisobutylene Primary Seal". This stuff remains flexible and is very tacky.

The pros seal the glass with some pressure at about 140 °F. Perhaps you can apply some weight and use a hot van in the summer sun?

Good Luck!

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Why do you want/need a vacuum? This negative pressure will actually be a force constantly trying to suck outside air in. Build your two pane system on a dry hot day, seal it well, but before you do, throw in some silica gel beads to absorb any moisture that might get in.

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Thermal conductivity of Argon vs Air:

Air, atmosphere (gas) 0.024 Argon (gas) 0.016

meaning if I am right, that there is not much difference as low thermal conductivity means good insulation.

metals are good conductor of heat have high thermal conductivity. example: Aluminium 205

PVC even has bigger conductivity than air Polyvinylchloride, PVC 0.19

so , why would you want to fill the space in glazing by Argon?

No gas in between makes sense. But air and argon? can't see the difference to be much of much!!??

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"not much difference" -- I wouldn't call a 3:2 ratio "not much difference"; depending on which side you view it from, air is 50% worse or argon is 33% better. It adds up over the surface area. –  keshlam Nov 20 '14 at 1:24

If you use Butyl Rubber around perimeter except a small part and use a heat lamp to heat interior section, then seal the short part, it will be like canning tomatoes. When it cools, a vacuum will be formed !

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Creating glass to non-glass seals is a non-trivial problem. The problem scales as the window gets bigger. Making a 6" x 6" seal is pretty easy. Making a 6' x 6' is hard. Normal steel flexes more than you would suspect. You can't just glue two panes together without any support because they will flex and leak.

To make 8.5" x 11" panes is not too hard as long as you can do metal working. You just make a steel frame with slots, epoxy the slots with aquarium sealant and slide the panes in. The vacuum fitting has to be in the metal part of the frame. The frame generally needs to be welded together because unless you are an expert machinist it will not be air tight.

Needless to say, doing this will be insanely expensive compared to just buying double-pane glass.

Why do you want to put argon in it? Argon is not an insulator you know. People use it in welding because it prevents oxygen from reacting with the work metal.

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Kind of tangential here but file this away as another approach: I built a skylight 40 years ago out of acrylic sheets ("Plexiglass") using acrylic solvent to bond the edges of the double-paned center portion. It's still sealed after all these years. I didn't take all the precautions that were possible - leak testing and using adhesive where leaks existed; back filling with Argon; inserting gel to soak up moisture etc etc.

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You're only talking about 15 square feet of surface area.

I would just use some thick single-pane low-e glass and be done with it.

Use the time and money to improve your house's energy efficiency in some more cost effective way, like adding some caulk somewhere or some better weather stripping around a couple doors.

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Pella windows uses an installed window and then a panel that is installed like a storm window on the inside. The sides of the window has vents on each side high and low. No fogging with insulating qualities. The windows I had never fogged. If you have tools and some skills this could be attempted. Their gap was near 3/4" but some insulating qualities could still be achieved in the space used for insulated panels.

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A vented storm window doesn't seem to answer the question of how to build a double pane argon filled window. –  BMitch Sep 8 at 12:38

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