Trying to protect my Super Cobra bezel glass

[angryred]

I have an original Stern cab Super Cobra; the bezel glass has the bezel image painted on the backside. Overall, it's still in pretty good shape but some areas have started flaking off.  Anybody have any suggestions on the best way to retard this deterioration?  The plan I'm juggling in my head involves cutting some paper masking in the shape of the clear area, then spraying the painted area with some clear gloss coat. Is that a viable option?

[SavannahLion]

From what I've seen on by the Pinball restores, the method is to spray Triple Thick (Decoart sells a similarly named product, don't know if it's the same thing) over the entire back glass, not just the flaking area. I have a Centipede bezel that's flaking and the last numbnut put clear packing tape over the back. Ruined the whole thing (it's further damaged by some big chips).  

I've never been able to find Triple Thick at my usual hunting grounds. But then I haven't searched especially hard for it either. Michael's, JoAnn's, Home Depot, Lowes would be the first four places I would check. Otherwise, order it online.

added: I don't think spraying only part of the bezel with anything will help. It would only make it worse. The cause of the cracking is described in the link above. It's due to the glass and paint expanding/contracting at different rates. I've had this happen a lot when painting when I mixed and match different types of paint and it's even used in the art world for a crackle effect. The glass/paint on the bezel just took longer to reveal itself. Point is, if you spray just a patch, you still have the rest of the art setting up to crack. But now you've got a layer of paint over the cracked area. What I imagine will happen is that new cracks will appear in a ring just outside of the spray zone.

The correct way to repair it is to strip the old junk off and repaint. But since no one is doing reproductions on glass, the next best thing is to try and protect what you have now. Spray the whole thing, or wait until a better technique comes along. It's going to be an all or nothing deal.

[angryred]

Wonderful! Thank you so much. The pinball restoration link was just what I needed.  I was planning on using the regular Krylon clear coat, but I'll look into that Triple Thick stuff. Thanks again.

reply to added: Yeah, I was just worried that if I sprayed it all over the clear portion, it would be visibly noticeable, or might yellow with age down the line. Admittedly, the pinball restore guys are working with much smaller clear areas, so I wonder if I need to consider that when choosing a product.

[SavannahLion]

It's hard to say how it would react in that environment. I tried to pull up the MSDS on Krylon's page and it won't come up. A little disconcerting if you ask me. I found the MSDS at msds.com but I don't feel like registering to see it. In any case, I would guess it's some kind of acrylic.

If I understand its intended purpose. It's designed for art applications such as pottery and flower preservation. So it shouldn't yellow, but I wouldn't bank on that. With care yellowing shouldn't happen for a long long time.

Long boring read, you may exit post at this time

Keep this in mind. Degradation is inevitable given the environment these things are in. Watching the projects unfold here, it's obvious that not everyone considers (or is capable of) extended term preservation of their cabs. Before any of you pipe in with your criticism, many cabs used incandescent bulbs for their light source. That's a nice hot source right there. But many then move into florescent (a common alternative) and you remove a huge portion of heat, but you then add in another problem. UV damage. UV damage isn't always immediately obvious and many of the layered glass paints seems to serve to protect the art from some fading.  LED's are better as long as they don't attempt to use UV in their formula to generate light (UV LEDs exist). Organizations like Xeroderma Pigmentosum Society have ample concern about UV sources. Archive groups have tons of research regarding UV and heat damage (they're far more ample than XP information).

Then you have outside influences depending on the cab design. Overhead incandescent lamps are a source of UV source. The HVAC is almost always going to create a temperature differential between the outside of the cab and what's inside. Given the fact that many of us often keep our cabs in less than ideal environments (garage for instance) these temperature swings are even more prominent.

Let's assume you never power the marquee light. That doesn't matter. Archivists depend on a closed box to help regulate the environment of the documents. If the outside temperature is a steady 60 degrees. Then the inside of the box will also be 60. But if the temperature and humidity were to suddenly rise to say... 80 degrees. The inside of the box will not rise as quickly. The temperature increase is a little bit more gradual since the box helps act as an insulator. A marquee is weird since you have some situations where the inside changes faster than the outside and you have the outside that changes faster than the inside. The problem with a marquee is the marquee itself is part of the box and that box sometimes has holes cut for venting the excess heat (from the incandescent bulbs). You power on that marquee and you are going to get the rapid temperature swings which is what you don't want if you are interested in preservation. Incandescent are going to be the fastest and the worst, followed by flourescents and finally LEDs. Leave that sucker on then the environment is going to have those wild temperature swings in comparison to the box.

Based on what I know the degradation process isn't something that happens overnight, but anywhere from weeks to years. So a twenty+ year old marquee cracking like that is to be expected. Modern inks and paints have UV resistant formulas to slow the process. But it's resistant, not UV proof. UV damage is cumulative. So something left in direct path of a UV source will eventually degrade, it's just a matter of when.

Yeah, the whole thing is kind of ugly. There are possible solutions, but I've never seen anyone else ever concern themselves with anything other than heat generation. So I've never seen anyone design marquees around preserving them other than the obvious means (removing excess heat for one).