Curing bullseyes under pressure.

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Brent Deines
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Re: Curing bullseyes under pressure.

Post by Brent Deines »

I almost never pressure cure. In fact I can't remember the last time I did. A pressure ring caused by excess heat, excess pressure, delamination, or a combination of the three has absolutely nothing to do with curing under pressure.

It seems to me there are two different discussions going on here. (1) Pressure rings (2) Air trapped at the outside of the break.

(1) As stated above a pressure ring is caused by excess heat, excess pressure, delamination, or a combination of the three. Once you have this condition there is no way to get rid of it but in most cases it is preventable by properly adjusting the temperature of the glass and the pressure used to inject resin into the damage. If the windshield is more than 10 years old (sometimes less than 10 years old) or if the damage is very severe the glass may already be separating from the PVB. In either of these cases the resin may seep out between the glass and PVB even under minimal pressure or even no pressure at all and there is nothing you can do about it, except to refuse the job of course. If you note either of these conditions the customer should be advised of the possibility of a pressure ring or "flowering" before the repair it attempted. A pressure ring may appear as a very slight transparent ring around the outside of the repair or may have a watery look. While most frequently seen on bullseyes and severe combination breaks, pressure rings or flowering may occur at the edges or ends of cracks as well.

(2) If you still have air trapped at the outside of the break before you cure, whether still under pressure or not, you have not satisfactorily filled the damage. Removing the bridge will not allow air to seep back to the outside of the damage but if you have simply compressed the air to the outside of the damage, which may make it appear that it has been properly filled, releasing the pressure may allow that air to decompress and become visible at the edge. Again, if that is what is happening you have not properly removed all the air. Curing under pressure in this circumstance may make keep the air compressed very tightly at the edge so it is not visible but it does not remove the air. This is a shortcut in my opinion and not the proper way to complete a repair. Air trapped at the edge of the damage will appear black or dark green so it is generally easy to differentiate between air and a pressure ring.

I've never seen a system that did not allow you to cure under pressure but speaking for Delta Kits systems I can tell you that it is rarely, if ever, necessary. If you find you need to cure under pressure using a Delta Kits system i encourage you to call for technical support. You are not properly removing all the air from the damage! I cannot speak for other systems but I would hope you are all using a system capable of removing the air from the damage.
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Re: Curing bullseyes under pressure.

Post by clearquest »

GlassStarz wrote:If you fill the bull to the max and cure under pressure you will see nothing of the circle. This a a fact couple thousand done myself to prove the fact. If your equipment doesn't allow pressure cure go the other way. MINE DOES.And it works. If your gear does not allow this I'm sure you honestly believe it doesn't work because for you it doesn't.
Thank you Brent for clarifying this. Curing a bullseye under pressure has ZERO to do with eliminating a visible outer ring. A properly repaired bullseye using a quality resin will have no ring and will not require curing under pressure. That ring is caused by using too much pressure or too much heat and once that has happened, curing under pressure will not fix the problem. There is no need to pressure cure a bullseye that has been repaired with correct tecniques. And "resin shrink" is not something that occurs to cause a ring. If shrinking resin is a problem on your repairs it's time to switch to a quality resin or reexamine your repair tecniques or come up with a better excuse!
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Re: Curing bullseyes under pressure.

Post by GlassStarz »

Sorry scooter but science is undeniable fill it completely then cure. The flaw in our systems is once you get it full you remove the injector and release the pressure some flows out. Basic science now some manufacturers make a system that if exposed to direct UV may freeze from cured resin so they tell you not to do it.Come up with excuses but the undeniable fact is Fill Completely then Cure under pressure you will achieve the closest to invisible result. This is similar to the vacuum argument some systems draw little or no vacuum so they tell you it's not needed again basic science a fluid will draw into a vacuum better than without. Result a better filled break with a better looking end result. I realize a lot of guys out there only know what they have been told by whatever system they use but it would behoove you to pick up a little knowledge as to the basic principles of why what we do works. Much like Mechanics some know how to change parts others know why the Engine works and the principles behind it. Which one do you want to be?
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Re: Curing bullseyes under pressure.

Post by Brent Deines »

So by that logic, if you fill a glass to the top and then spill a little out, the air space will be at the bottom of the glass. I'm afraid that is not the way it works. I have spent considerable time with engineers over the years and I have to agree with clearquest. If you got all the air out of the damage to begin with, removing the injector will not put air back around the edge of the break. To go one step further, if you place a drop of pit resin on the surface and cover it with a curing tab, any remaining air at the top of the damage is thereby displaced.

Another example would be the brake system in your automobile. If you do not bleed the brakes you may have an air bubble anywhere in the system but if you properly bleed the system all you need to do is make sure there are no leaks that allow air to be drawn back in when the brakes are applied (pressure) and released (vacuum). The air in the top of the reservoir does not migrate back into the brake lines and certainly does not go to the end of the system furthest away from the reservoir as long as you keep the fluid level in the reservoir above the brake line.

Therefore, the only way for there to be air around the edge of the damage is if it were never removed to begin with, but was simply compressed to the point that it was not visible to the naked eye. That would be the only reason to cure under pressure...to keep the air hidden.

There is one possible exception. If any part of the damage, save the area covered by the end seal of course, reaches the surface of the glass, air may be reintroduced into the damage any time there is not sufficient pressure within to hold the air out. However, if you have damage that reaches the surface, any significant vacuum used to remove air from the damage will actually pull air from the surface back into the break. But if we are talking about the ring around a simple bullseye with the only damage reaching the surface being the impact point that is completely covered by the end seal, this argument does not apply. That ring is either air that was never removed to begin with or it is a pressure ring caused by excess heat, excess pressure, old glass, or simply damage severe enough to cause the glass to separate from the laminate. More often than not it is a combination of these things.

Generally this discussion ends in name calling and people getting upset but I really hope we can continue in a respectful manner as I think this is a very misunderstood concept that is quite easily explained if we have a look at what is actually going on when we displace the air in a damaged lite of glass with resin. I also think that proper understanding of this concept will help technicians, regardless of the system or resins they use, do better repairs.
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Re: Curing bullseyes under pressure.

Post by clearquest »

once again, thank you Brent for giving an accurate explanation to this misconception.
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Re: Curing bullseyes under pressure.

Post by GlassStarz »

Sorry but you couldn't be farther from the facts. Release the pressure it dribbles out. Leaving the outside of the ring unfilled. If you used you vac cycle correctly there isn't any air of course if you system doesn't offer vacuum not sure what flagrantly. Maybe your understanding of how things work is due to your systems being limited. I use one that pulls the air out causes a vacuum so when I fill it pulls into the furthest edges. Some systems simply pressure the resin in and give no real vacuum.
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Re: Curing bullseyes under pressure.

Post by clearquest »

Hmm, I've done nearly 16,000 repairs and never had resin dribble out and cause a ring around a bullseye. Also rarely ever had the need to cure under pressure. Dang I'm either real good at what I do or real lucky! Science? Facts? Logic? Thanks again Brent for operating a forum that strives to provide accurate information.
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Re: Curing bullseyes under pressure.

Post by t4k »

clearquest wrote:Hmm, I've done nearly 16,000 repairs and never had resin dribble out and cause a ring around a bullseye. Also rarely ever had the need to cure under pressure. Dang I'm either real good at what I do or real lucky! Science? Facts? Logic? Thanks again Brent for operating a forum that strives to provide accurate information.
Hear, Hear!!!
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Re: Curing bullseyes under pressure.

Post by Brent Deines »

GlassStarz wrote:Sorry but you couldn't be farther from the facts. Release the pressure it dribbles out. Leaving the outside of the ring unfilled. If you used you vac cycle correctly there isn't any air of course if you system doesn't offer vacuum not sure what flagrantly. Maybe your understanding of how things work is due to your systems being limited. I use one that pulls the air out causes a vacuum so when I fill it pulls into the furthest edges. Some systems simply pressure the resin in and give no real vacuum.
I have dozens of different types of windshield repair systems and have used them all. In fact I think it is safe to say that not too many people own more windshield repair systems, or have used more windshield repair systems than I have, so although I do not claim to be an expert on all of them, I think I have a pretty clear understanding of how they work.

You don't need high vacuum to pull from damage and after working with a number of engineers I don't believe it is possible to remove "all" of the air from the damage before you allow the resin to flow in. If you need evidence of this all you need to do is use a high resolution digital microscope to monitor the repair process. If you really want to get technical there is air in the resin, and even in the glass, so no system is truly removing "all" the air, but all we are really concerned about here is air that is visible to the naked eye. If you were able to pull all of the air out of the damage there would never be a reason for a second vacuum cycle. If you "never" use a second vacuum cycle I suspect that is why you are leaving air around the edge of the damage.

We have a number of videos showing exactly how our system works and clearly showing the air being removed from the damage, ending the argument that high vacuum is needed to remove the air. We also have videos that clearly show damage sometimes reaches the surface outside the area covered by the end seal obviously making a high vacuum system ineffective for this type of damage. Still, some people prefer high vacuum systems and that is fine. That is a personal preference and some people will have better luck with one system while others will prefer a different one.

We have videos showing a bullseye being filled start to finish. We remove the bridge, add a drop of pit resin, cover with a curing tab and cure. We do not cure under pressure and no air appears at the edge of the break. How do you explain that?

I believe we also have videos showing a pressure ring that is visible before the bridge is removed, and still visible (no more and no less) after curing. We don't have a video showing that curing under pressure has no effect on a pressure ring but we can make one if we need to in order to prove this point. No problem!

Because everything we say is challenged by someone like yourself, and that is not a bad thing, we have to prove what we say is true by documenting our entire process. We do not have the luxury of throwing out undocumented claims. Therefore, I submit that the best way to end this debate is for you to make a video of your entire process for filling a bullseye and post that video here to show us all how when you remove the bridge air appears at the edge of the damage. Then show how when you cure under pressure you don't have that problem. I'll then post a video showing how I repair a bullseye and remove the bridge with no air appearing at the edge of the damage, thereby eliminating the need to cure under pressure. We will then let the "facts" stand for themselves and let anyone viewing this forum make up their own mind.

Does that sound like a reasonable proposal?
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Re: Curing bullseyes under pressure.

Post by clearquest »

I think thats a great idea Brent. I for one would love to see an instructional demonstration done by GlassStarz that shows what he speaks of. I want to see the scientific facts of his bullseye repair process. I think that when you choose to dispute a respected expert, you should be willing to show the members of this forum the proof. Clearequest (aka Scooter)
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