Windshield Repair Forum

I did several repairs over the weekend on bullseyes and it went great when looked on the outside. But when looked inside, I can clearly see the ring around the bullseye. From the forum posts, the ring is caused from pressure which may expands the laminate a bit. Just wondering if this is normal for everyone or do I have bad resin. I've been very careful of how much pressure I applied when repairing and I don't think I used that much pressure at all.

A few things that can cause rings are of course bad resin(or resin that is too thin), too much heat used when filling the break(a bulls eye shouldn't require any heat at all), or too much pressure applied to the glass by the injector base seal.
Not using the right resin for the job can be the biggest problem, unlike a star a bulls eye goes down to the PVB. The wrong resin can cause a reaction between it and the PVB giving you the ring.

Merci

Yvan I have got to disagree with you on this one I would say most starbreak legs do in fact run along the back of the glass which of course is connected to the pvb, thus starbreaks do connect with the pvb.

I use a very thin resin for all jobs Esprit which over the years I have found to be unbeatable and have tried many many others along the way and would not say a thin resin has anything to do with pressure rings.

I have recently had someone come to my training course who had been told just to put the injector on the screen put some resin in it and apply pressure and watch it fill. Where is the air in the break supposed to go of course he always had pressure rings.

To avoid pressure rings I suggest using more time on vacuum and less on pressure if you leave a break for sometime on vacuum you will often find that it fills quite well without pressure depending on the type of break and of course your injector actualy being able to pull a vacuum which many do not.

The mityvac is a great tool when used to remove air from all types of breaks but it tends to show its best on bullseyes.

Try putting a small drop of resin onto a bullseye place the mityvac over it and pull a vacuum release and watch that resin flow.

Check your injectors to see if they do in fact pull a vacuum many rely on pressure built up when you first inject the resin to force the air back out when you release injector pressure they do not in fact pull a vacuum at all which is why I suggest the use of a mityvac or some other vacuum pump.

I'm using Delta's equipment and when pulling a vacuum on it, the air will leave the break. I'll do this several times until I cannot see any air left and the break is completely filled. I'm very careful about applying too much pressure. I only apply it when needed. And also, heat was not used. I do begin to believe that resin may be an issue here. I forgot to mentioned that I do cure under pressure and this might be the part of my problem also. But I would much rather cure under pressure (be on the safe side) than having resin running out of the break and causing a very incomplete and ugly repair. This has happened in the past. Any input would be great!!

Do not put to much pressure on yourself most bullseyes will have a slight ring around them. Try starting the injection cycle on vacuum first this will allow some resin to enter and air to leave the break buy just starting with pressue first you are basicaly trying to fill the break twice once with air that is already in there and then with resin this is one of the times when a pressure ring can occur without you realiseing it has happened, pressure rings do not only occur when on the last cycle but at any time on the repair process it may only be when you have finished them that you notice it.

I tend to not cure bulleyes under pressure unless they need it.

How much vacuum does the Delta injector pull or does it rely on pressure build up as I mentioned in my last post and have you tried a mityvac if you do not have one I suggest you get one they are a great help on problem breaks/ bullseye/ combinations etc. and of course a vacuum lowers the boiling point of water a great help when drying out.

Screenman

I may have miss translated in my head, you are of-course correct. This is the way it should have come out of my head in the first place, the cone of glass in the bulls eye, under the pressure of the injector and resin pressure, puts pressure on the pvb layer, pushing it down slightly alowing a bit of resin between the solid glass and the pvb(use a tinted resin on a test piece of glass and look at it wiht a microscope, you will see what I am talking about).
Starting off with a vacumm is of course the only way to go, to test if your injectors do indeed pull a vacumm, use your finger as a test. Without any resin in the injector, unscrew(or with draw) the center piston while your finger is pressed up against the seal, if you can remove your finger with-out a pop then you have no vacumm. I always start with a vacumm cycle, I put my resin in the injector, bring the resin to the edge of the seal, apply the injector to the glass, withdraw the center piston, creating a vacumm. This draws the air into the injector(you can see the bubbles passing through the resin)and allows the resin to gently flow into the break. If left long enough(about 2 mins) the bulls eye all but disapears, when appling pressure it is completly full within a few seconds. Use pressure(injector to glass, and resin pressure) sparingly on all repairs, if you need strong pressure than something is amiss.

Sorry for any confusion I may have caused.

Yvan

That is a very good description of how to do a bullseye. I have found very few injectors that can pull a reasonable vacuum I normaly test on glass.

Am I right in saying English is your second language if so it puts me to shame I have not got the hang of it yet and its my first.

magicogar wrote:I can clearly see the ring around the bullseye...Just wondering if this is normal

This definitely can be normal. To differing degrees, bullseye rings show up in most repairs. Now, I know there's a certain set of people on here that are clicking away at the reply button right now to say they NEVER get bullseye rings, and they always disappear. The simple fact is, bullseye rings can be normal.

A few of the things that can make bullseye rings worse:

• Excess Pressure

• Excess Heat

• Windshield Variables (each windshield is different, some are more predisposed to rings

• Windshield Age

• Break Variables

You've gotten some advice/explanations here that make sense, and you've gotten some that absolutely will not work for our system. Since you have unlimited technical support, please don't hesitate to call us and use it. In fact, if you don't call, Matt sits around and plays ping pong all day, and he's getting too good. Starting to get cocky...Anyway, definitely give us a call.

Unfortunately, i've got to dispel a few things here.

screenman wrote:I have recently had someone come to my training course who had been told just to put the injector on the screen put some resin in it and apply pressure and watch it fill. Where is the air in the break supposed to go of course he always had pressure rings.

Pressure rings are not air. If they were, the ring would be black/green etc..

screenman wrote:Check your injectors to see if they do in fact pull a vacuum many rely on pressure built up when you first inject the resin to force the air back out when you release injector pressure they do not in fact pull a vacuum at all which is why I suggest the use of a mityvac or some other vacuum pump.

magicogar wrote:I'm using Delta's equipment and when pulling a vacuum on it, the air will leave the break.

That is the goal of the vacuum cycle, to make the air leave the break. If all the air is out of the break, there is no reason to continue trying to remove what is already removed. Again, i'm speaking of the Delta Kits systems now, NOT anything else.

screenman wrote:Do not put to much pressure on yourself most bullseyes will have a slight ring around them.

Exactly. Unfortunately, it's very hard to determine from posts on the internet whether we are dealing with those rings or a significant problem. Again, call for tech support .

screenman wrote:Try starting the injection cycle on vacuum first

Again, this is manufacturer specific advice. Do NOT do this with your Delta Kits system.

repare-brise wrote:Starting off with a vacumm is of course the only way to go

For your Glass Mechanix system, i'm sure that's correct. Delta Kits systems do not operate like GM systems. Delta Kits systems operate on hydraulic pressure, rather than air pressure. That is, our system is not a closed system like your GM or some other brands.

repare-brise wrote:to test if your injectors do indeed pull a vacumm, use your finger as a test. Without any resin in the injector, unscrew(or with draw) the center piston while your finger is pressed up against the seal, if you can remove your finger with-out a pop then you have no vacumm.

That's a test they love to do at tradeshows, it's quite entertaining . Some brands out there tout their huge PSI vacuum & pressure. They definitely have more vacuum & pressure than ours does, and they need it! Why? Because they operate on air pressure only. Once they put the injector back down in the pressure cycle, it pushes the piston directly back down on the air that they worked so hard to remove, hoping that the air will then push the resin in the break. With our system, the piston pushes directly back down on the resin after the air has been removed. Any time you have an air pressure system, like the mityvac, GM, or a couple others, you will absolutely need that extra vacuum.

With our system, you do not WANT nearly the amount of pressure or vacuum that closed systems have. That's good, because as stated above, excess pressure is one thing that can cause bullseye rings.

Once again, vacuum is not magic. The goal of the vacuum cycle is to remove air bubbles from breaks. If your system can remove all the air from a break, it has enough vacuum. Pressure is not magic either. The goal of the pressure cycle is to inject resin into the break. If your system can inject resin into the break, and remove all air, then obviously it has enough of both.

The least amount of stresses that you can cause to that windshield/break and get it filled with all the air gone, the better. Adding additional pressure & vacuum adds unnecessary stress to that windshield, and can lead to a higher crackout rate, worse bullseye rings, and delamination.

Tech support is very difficult over the forum. You get very helpful people, who just don't know about the system you're using, trying to help by telling you what works with their system. This can be very confusing when trying to apply that to a system that operates differently. I think almost all of the major manufacturers offer unlimited technical support. I would highly recommend using that as your #1 resource.

Very nice follow up on this issue Jeff,

Aside from what you already mentioned as possible causes for leaving a ring I wanted to add one.

Contamination! I see this alot of this during the winter months here in Michigan. Bullseyes will absorb water, wiper fluid, salt and road oil. When repairing these it's not uncommon during these months to have a less than a perfect bullseye repair. You can dry out moisture and remove air but it's almost impossible to totally remove what's already soaked in damage. That's why it's so important to ask customer beforehand when damage occured, so you can better explain the finished results.

Jeff

Great reply, you are 100% correct in saying that the first resource is the manufactuor for tech advice and info. Unfortunatly not all companies offer the tech support that you and a few others provide(your gain there loss).

I must add something to what you said though, weather or not the piston or a minute amount of air is contacting the resin both can exert the same amount of pressure(many large industrial applications use an air over hydraulic system, the air is used a a shock absorber in those cases, as air will slightly compress, where as liquid compresses very little) The amount of air that is present in the injector is very minute(remember the air that is there came from the break and I don,t think a bull's eye contains a little more than a few cc's.

You are correct in saying that the amount of pressure is not important(you shouldn't require more than about 2-5 psi to fill a break), I do believe(IMO) though that the more vacumm you can create the faster the air will evecuate. But the important thing is to pull a vacumm of at least 2 inches of mercury(some companies claim rediculusly high figures for vacumm, I have seen some that claim 28 inchs, they must have done there testing in space)

Once agin thank you for your informative reply, and my answers were in no way meant to shed a shadow on your excellent system, sory if I offended you in anyway.

Screen man

Yes english is my second language, but I try to do my best.

Merci