window defrost grid

[HS30-H]

11 hours ago, Patcon said:

Do anyone know how the process was originally done? Seems that would help come up with a replacement process

@HS30-H

Roughly as the Captain suggests, I believe it was put onto the glass like a big transfer print.

[Namerow]

Answer is found at 0:40 in this slightly grainy PPG promo video...

https://youtu.be/SdHYcXGx4bw

[Patcon]

So the video addresses my other question. How was it silk screened when the glass curves in dimensions?

Evidently it was screened first and then heated and formed. I was watching somebody using flexible screens to decorate glasses. I wonder if you could order a screen that would flex enough to regrid the glass. In my mind I was thinking you would strip off all the old grid, buff it and then rescreen it. That eliminates the need to line up exactly with the old grid...

[zKars]

or just

https://frostfighter.com/clear-view-defrosters-about.htm

or 

https://frostfighter.com/defroster-repair-grid-kit-2100.htm

They have a bunch of cool products

[Captain Obvious]

53 minutes ago, Patcon said:

So the video addresses my other question. How was it silk screened when the glass curves in dimensions?

Evidently it was screened first and then heated and formed. I was watching somebody using flexible screens to decorate glasses. I wonder if you could order a screen that would flex enough to regrid the glass. In my mind I was thinking you would strip off all the old grid, buff it and then rescreen it. That eliminates the need to line up exactly with the old grid...

The bend in the hatch glass is subtle enough that I wonder if someone who knew what they were doing could silk screen that after it had been formed. I'm no silk screen expert, but I wouldn't be surprised if they could deal with that gentle bend.

In my distant work past, I was a customer of several membrane keyboards and that technology typically uses a lot of silkscreen processes. I've never done it myself, but my employer bought lots of them and I got closely grazed by much of the technology.

[Dave WM]

I have seen the frost fighters, I am not sure I like the idea of a stick on product, but perhaps it will work better than what I am trying. If this stencil product does not work out I may go that way.

[Zup]

Dave,

Late to this discussion but--- I made readings from a NOS hatch glass with horizontal defroster grid that I was fortunate enough to find and purchase recently.

Using the 200 ohm setting on the VOM 1.6 ohms was the resistance value measured.

I've thought in the past when S30driver and I were discussing this that we might reach out to frost fighter and see if they would consider a purpose built replacement grid for our Z's that would exactly register over the original element lines.

Since almost all defrosters on our cars are non-op and that no source currently offers replacement hatch glass with the lines, there might be enough of a market that they would go for it at some price point.

I'm reluctant to utter that iffy phrase "Group Buy" , but pre-sales might provide leverage as an inducement to them.

[Dave WM]

I will see how this works but yes if there was a proper made to fit Z hatch glass replacement I would def try it, if I fail at this attempt. I too assume there are no functional defrost grids left on 40+ year old cars. I tend to try to keep things original as possible hence my reluctance towards going with a generic kit.

[Zup]

Quote

 There is no plastic backing left on the window to crack or yellow.

That was lifted from frost fighters website.

Apparently there is no residual material after application---only the lines.

A purpose built grid that matches in lengths, spacing and element thickness should be as close to original as one is probably going to get and in my mind would likely be a better performer than a mix of old and repaired segments or a new conductive grid with irregular thickness (hence resistive) properties.

I appreciate your "do it myself" approach and applaud you for it. My only intent here is to see if there is interest in a quality one source solution that virtually anyone can purchase and install with a minimum of hassle and a maximum of performance.

Edited September 8, 2020 by Zup

[Namerow]

One potential issue that I didn't see discussed in the FrostFighter online materials:  Is the stick-on grid sufficiently thin*-yet-robust that it will tolerate occasional cleaning of the rear glass surface with glass cleaner?  That's one of the strong points of the OEM grids  --  they seem to be ok with paper-towel-and-windex cleaning from time to time. 

(* by 'thin', I mean height above the glass surface)

[zKars]

I have the frost fighter grid on my 510 rear glass. It’s pretty tough yet thin. No problem cleaning it with a rag and invisible glass cleaner so far. 

 

[Dave WM]

well I tried the stencil works well to keep a thin straight line. I have to work on my technique for applying the paint. I purchased a pin stripe brush, but I am not very good at using it. I cant seem to load enough paint for more than a couple inches at a time, and the transitions are not that great. So now I am practicing stencil free just drawing lines on a round glass tube (old light) to try and get better at the application before testing with a stencil again. Clearly what ever the process is, it will be very tedious considering the amount of lines needed to be painted. This is prob what sidelined me last time when I 1st started this thread.

I suspect the biggest issue with this will be even if I am able to apply and it looks good and works well the paint itself maybe too fragile for any kind of cleaning. Its water based and seem to have low adhesion just going on. I will let what I have done dry overnite and then try cleaning with some glass cleaner and paper towels (pretty rough but what is typically used) as a durability test.

Edited September 8, 2020 by Dave WM