Has anyone used a mylar coating on plate glass as an alternative to replacing the glass with safety or tempered glass? Sounds like it would work since it is used commercially for smash and grab protection on store windows and display cases.
Would there be insurance issues if you had an accident? Don't know just asking.
Yes, it would greatly increase safety. I can't comment on the insurance issues. Ideally you'd want the film to go to the edge of the glass inside the frame. There are films that serve this purpose in hurricane-prone areas.
Note that there are LOTS of different types of window films. A thin film that is intended just for UV-blocking would not be suitable here.
All-in-all, it is probably simpler and not much more expensive to just get the right glass.
I have not priced the film coating or glass replacement yet but the auto security mylar made by Llumar is pretty darn impressive. No one down here in Florida wants to cut the glass for my Centerdoor but there are tons of places that do the mylar film.
Mylar films were my business for 28 years. Sales, installation, distribution, consulting. And yes, I've treated two windshields in this way.
Chris is correct, a clear safety/security film is required. Typical solar-contral films are 0.001" thick, whereas safety/security films are 0.004", 0.007". 0.011", and 0.015" in thickness.
It stands to reason that the thicker the better, but there are tradeoffs — even the tiniest speck of crud (hard to avoid around a T windshield frame!) will create a visible blister around that speck, and the blister will be much bigger with thicker films.
The adhesive on satety/security films is a PS or Pressure-Sensitive type. It goes on with slightly soapy water, but needs very firm and slow squeegie strokes with a hard-edged plastic squeegie to achieve a good bond.
A good compromise is the 0.007" film applied to BOTH sides of the glass to yield a much more protective glass sandwich.
I've done this to the plate glass windshield in my very original '26 Touring because I want to keep the car as much original as possible. Also did it to the original plate glass windshield of a friend's Model A so he could keep a period sticker (gas rationing IIRC) in place.
This is not a particularly appropriate job for the DIYer, as the result will be lots of edge specks and/or wasted material trying for a clean install and/or insufficient bonding because of being too gentle with the squeegie.
A professional installer could give you a good job if they are careful and care about the results, but your best bet is probably to just replace the original plate glass with laminated automotive safety glass. If you are having trouble finding a shop to cut safety glass, ones that work on semis always have this ability.
Dennis: If the insurance company is going to squack about mylar-coated windows chances are they will really be upset with your brakes, seatbelts, headlamps, turn signals and any of countless other deficiencies from modern standards!
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Edge trimming before final squeegie passes:
Hard squeegie pass
Thanks Chris, that is the information I was hoping to get. I plan to look at both options before I make a decision but I wanted to make sure the Mylar was in fact a viable option. Cost is a consideration too but my primary objective is safety with maintaining originality a close second!
A check of FL regs finds any vehicle such as Model T must have safety glass windshields
Dan thanks for that information. I know that is the case and I plan to replace the windshield glass with safety glass as I have done on all my other cars but, as far as I know, there is no requirement for the rest of the glass. I am looking for the least invasive solution to a safety issue as I don't want to start tampering with the interior of an original car if it can be avoided.
Thanks for posting this. This looks like a good alternative for my TT truck. Safety glass in the windshield is no problem. The side windows, however, are thin. Like only 1/8" or so. The wooden frame work around the side windows is not designed for thicker glass. I had considered using Lexan, but just couldn't bring myself to do it. This film might possibly allow me to use the original glass. I'm gonna look into this. Thanks again.
You can get 1/8" glass tempered. In the glass world - at least around here - that thickness is called "double pane".
Val: If your "interior of an original car" includes the original door panels, I would recommend AGAINST the film option. There is always considerable water involved in the installation, and I would not want to risk damaging/staining any original upholstery.
Hal: glass that thin would likely be better coated with the lighter 0.004" safety film, as the pressures required to achieve a decent bond with the thicker films increase the odds of breaking such thin glass. Of course, glass breakage whilst installing film is always a possibility.
Chris: Yes, 1/8" glass can be custom cut and tempered (in that sequence) and while it can be costly, may be the better option for Hal.
As you probably know, but others may not, tempered glass is what vehicle manufacturers use for side and rear windows — harder to break, but when it goes it shatters into tiny, relatively non-dangerous, bits.
Around here, the old fashioned term for 1/8" glass is "Double-Diamond". "Double pane" glass always refers to dual pane/insulating glass, typically sealed to a 1/2" perimeter spacer and often with an argon-filled airspace.
Chris, you make a good point. While I did think about the water issue and planned to cover the interior with plastic and masking tape then drape towels over that to absorb the water, I never thought about ruining the panels if water got past that protection. I am wondering about just using the mylar on the outside of the glass to avoid any issues with the door panels as they tell me they often coat both sides of the glass for maximum shock resistance. I am beginning to see why all my other cars are open cars. Just having a windshield to worry about was a lot easier.
Sorry - I thought one thing and typed another. 1/8" glass is called "double strength" or "DSB", not "double pane".
Anybody have an idea of what tempered glass is going for at retail these days? I haven't bought any for a while, and I was buying at wholesale, but I would think it would be on the order of $10/sq ft with a 4-5 sq ft minimum per piece. A bit more for edge finishing. I'm in a pretty expensive area for glass so it might be less elsewhere. (Glass takes a lot of energy to make, energy is relatively expensive in the Northeast, hence there are not a lot of glass plants around. Supply and demand . ..)
When you calculate the size of your glass, be aware that in the glass world it is common practice to round up to the next even numbered inch for pricing.
I looked into tempered glass a few years ago. The glass company I talked with wasn't real interested. They said they could cut the glass and send it off for tempering, but if it got broken during transit, they were not to blame and also wanted to make sure I knew it was going to be EXPENSIVE. I guess I let them scare me off, because I never pushed them for a price.
I did check into the safety/security film yesterday. I found a company that does it. I made the mistake of telling them it was for an antique car and they immediately said they weren't interested. I then told them I could just bring them 4 pieces of glass. She said she would have to speak to the owner. I got a half a mind to call'em back and give'em another name and tell'em its for a display case.
A glass dealer shouldn't have to cut glass, then send it off to be tempered. They'd just order a piece of tempered glass from their supplier to whatever dimensions or pattern you give them. I used to do this on a weekly basis in a previous life. You just need to find a friendlier glass dealer.
I would think that safety glass all around makes more sense than tempered glass in the side windows. I finally got a quote of $18 per square foot for safety glass with the caveat that the actual square footage should be multiplied by 1-1/2 for waste. I have nothing to compare this to so I don't know if it is a rip off or not. I am thinking that it will cost close to $1,000 for a Centerdoor and that seems way to high to me. That is why I am exploring the mylar option. In the past I have spent $150 for a 2 piece windshield and there I had to buy more glass than I needed so based on that I would think it should be around $500 for the windshield and the side windows on a Centerdoor. Does anyone have a handle on what it costs?
Model T windshield glass is 1/4" thick. If you tried to use 1/8" tempered glass (I can't imagine why you would want to do that????) it would be crazy loose in the channel.
I had safety glass cut to fit the original channel in my '13 it cost something like $40 for one pane of 1/4" automotive safety glass. The guy did it while I stood there.
I had the windshield glass cut for Barney ('25 windshield) about a year ago, and I think I paid all of $75 for it I will have to polish the visible edge, but that's easy to do, just takes a little time (wet/dry sandpaper and water). I would think you could get the centerdoor glass for way under $500. It IS harder nowadays to find a glass shop that handles safety glass though. Changing times; folks don't have single pane house windows anymore, so there goes that large market (especially around baseballs.)
Then thin glass I was speaking of is NOT for the windshield. It is for the side windows in my TT which has an aftermarket cab. It used this thin glass with thin strips of wood nailed behind it to hold it in. Laminated safety glass is too thick to go back in there. The strips of wood that retain the glass are narrow enough as it is.