Here is what Clay says (http://www.pinrepair.com/restore/index1.htm#bg)

Preparing the Backglass for Triple Thick.
Before spraying the backglass, clean it if possible. If there is any or significant ink/paint flaking, skip this step! If the ink/paint is mostly intact and just starting to delaminate, I would suggest this. Often a backglass can have a thin film of oil, grease or other crud on it from the stepper units and score reels. If this is not removed, the Triple Thick may not "stick", resulting in "fish eyes". Because of this, I personally find it is best to try and clean the painted side of the backglass if possible. Again, if the backglass ink/paint is starting to delaminate, skip this step!

To clean the painted side of the backglass, take a paper towel and spray the paper towel with Windex (don't soak it!) Never spray Windex directly on the backglass. Spray the Windex on the paper towel. Now gently wipe the score windows and credit window. After doing those, *gently* wipe any other "solid" (not delaminating) sections of the backglass. Remember, don't go nuts and cause more problems. "The enemy of good is better" is something that should be repeated while doing this chore. Examine the paper towel for crud or potential paint loss. See all the dirt on the paper towel? Removal of this crud really helps the Triple Thick "stick" to the backglass ink/paint.

On backglasses with score reel windows, a business card can be cut and layed over the clear score reel windows. Use a penny or a nickle to hold the card down. This is optional (often I just spray over the score windows completely).

Applying the Triple Thick.
After the glass is dry from cleaning, it is time to spray the Triple Thick. Put the backglass flat on a solid surface. If the backglass ink/paint is really delaminating, I spray the first coat of Triple Thick about 18 inches from the glass, and move the can very quickly. This will provide a "misting" coat to get the delaminating paint to stay in place. Then let this coat dry a minimum of 30 minutes. A repeat of this quick and distant application may be required. If the backglass is not delaminating, my first coat is about 12 inches from the glass, and I move more slowly, applying more clear in a "wet" overlapping coat.
If the backglass is heavily peeling, please skip down to the section below, Saving a Severely Peeling & Flaking Backglass.

After the first coat(s) of Triple Thick is down and dry for at least 30 minutes, I spray one or two more "wet" coats. The first coat of Triple Thick should have all the backglass paint solid and in place. So the "wet" coats can be applied with the spray can much closer to the glass, laying down much more Triple Thick again in a "wet" coat. Spray the coats in perpendicular directions if possible. That is, spray left to right on the first coat, and then up and down on the second. I find that at least 30 minutes of dry time between coats is needed.

A common question is, "how much Triple Thick do I need to apply?" Generally speaking, two wet coats is all that is needed. Do not go wild and apply more than that. Too much Triple Thick can be a bad thing (but also too little Triple Thick does not really protect the backglass).

On backglasses with score reel windows, if they were not masked before spraying, they can be razor bladed to remove the Triple Thick. Note if the proper amount of Triple Thick was applied (not too much!) and the windows were clean, I often leave the score windows with the Triple Thick on them. If you did a nice job spraying, usually the Triple Thick can not be seen. If this is not the case, after 30 minutes of drying time on the last coat, use a razor blade or exacto knife and score the outside edges of the score reel windows. Do this about 1/8" on the inside edge of the paint. This allows the new finish to overlap the backglass paint. If you allow the paint to fully dry before scoring it (not recommended!), heat your razor blade or exacto blade so it is hot, then score the paint. The heated blade will cut the clear coat much better.

After scoring the new finish, scrap/peel the clear from the windows. Use the razor blade for this job (or a razor blade broken in half). I usually do *not* razor the credit window. When complete, let the glass dry overnight. Then use Novus#2 on the score windows to remove the "edge" from razor blade scraping.

Saving a Severely Peeling & Flaking Backglass.
Mark got me going on this, and here's my take on it. If the backglass has a lot of curled, flaking, peeling ink/paint, but most of the "ink pieces" are present, there is a way to save it. This technique will also minimize the amount of touch up required to fix the peeling ink/paint.

The problem with flaking backglass ink/paint is the loose paint chips tend to curl up. Spraying Triple Thick usually will not make the paint chips 'lay down'. So we need some techinque to get them flat, so they will re-attach to the backglass.

The trick here is to use "plastic wrap" (I have found the Glad brand "ClingWrap" to work best). The plastic wrap will act as a barrier between you and the wet Triple Thick. The trick is to spray a "wet" coat of Triple Thick on the backglass. Then right after the Triple Thick has been sprayed onto the backglass, put a layer of ClingWrap over the wet Triple Thick in the areas where the backglass ink/paint is peeling. The ClingWrap doesn't have to be stretched tight, and it only needs to be applied in the areas of peeling paint. Try and apply the clear wrap with no creases if possible. The reason for this is simple: if Triple Thick gets inside a crease, the clear wrap will have a harder time coming off the backglass after the Triple Thick dries.

Applying the Cling Wrap over the wet Triple Thick on a heavily peeling backglass.

After the Cling Wrap is on top of the wet Triple Thick, press the clear wrap down with your fingers in any area where the backglass ink/paint is peeling. Actually push down the peeling paint. Paint chips can even be shifted and moved slightly if you are careful. The ClingWrap will keep your fingers separated from the wet Triple Thick. After all the paint is pushed down and into place, leave the glass alone (do *not* try and remove the ClingWrap!)

Removing the Cling Wrap from the backglass after the Triple Thick has dried.

Now let the Triple Thick dry overnight. This is very important! The Triple Thick must fully dry before proceeding. After drying, the ClingWrap should peel off the backglass very easily, without bringing any paint with it! It should come off so easy, the ClingWrap should almost fall off. If it doesn't, the Triple Thick is either not dry, or there are creases in the Cling Wrap, which have trapped the Triple Thick, making it difficult to remove. Leave it alone let it dry longer. If the ClingWrap still won't let go from the backglass, sometimes a quick spray of 'cold freeze' (spray cold in a can, often used to remove mylar and to test electronic components) will release it. But be careful, as you don't want to get the backglass so cold that it delaminates the ink! (That would kind of defeat the whole purpose of this exercise.) If the ClingWrap still won't come up (rare, but I have heard of it happening), don't force it. Just trim off what you can with a razor blade and leave it alone. Note I have tried other products, but ClingWrap seems to work the best. And no, wax paper should not be used. The solvent in Triple Thick reacts with the wax, and makes a big mess (the Triple Thick doesn't dry well because of the wax).

Note there is some "texture" to the Triple Thick where the ClingWrap was removed. Don't worry about it, that is to be expected. After the Cling Wrap is removed, apply a second "wet" layer of Triple Thick to the backglass. Spray this second coat perpendicular to the first coat. The "texture" will go down a bit with this step, and the second coat locks the peeling ink/paint down even better. After the second coat is dry, the backglass is ready for touchup!

Yes, I am reviving a two year thread!

I tried this yesterday with Costco's own, Stretch-tite and I cannot pull it off without pulling the paint

I guess that's why Clay states Glad

I'm going to simply leave it in place, but rather annoying

Anyone else had different results with different makes of cling film?

I do not recommend cling film at all. The risk of pushing down paint in the wrong location is too great... and when it happens it looks terrible.

Ah, that's interesting Nic, do you have an alternate approach for a badly flaking BG?

When you triple-thick clear your backglass, you must imperatively cover the score windows with tape. I use regular invisible tape cut perfectly so as not to overlap the backglass design.

Without this precaution, it will be very hard to read the score reels or the displays.

Yves

How long did you wait for it to dry? Wait 24 hours minimum.

There is another technique, especially if you have tinted score windows. Just spray the windows with a couple of thick coats, and it will dry clear. Then you can level out the area with novus, if necessary.