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Round bead vs V bead

Bob Barenek,

I have several questions about the article you wrote.


The 1st question is the contact bonding area of a round bead vs V bead.In your illustrations.You state that round bead will squeeze oval in the best case scenerio.Would the type of viscosity urethane have a determining factor?Example would a low viscosity product squeeze flat instead of oval according to decking height?Also when using a low viscosity product the v bead can not support the weight of a windshield to get the required decking height of a metal clip molding or a encapsulated windshield?

The 2nd question would be pertaining to the lap shear psi to contact surface area of a v bead versus round bead.This is of course depends on the viscosity of the urethane used.While the v bead you illustrated has a larger contact surface on the pinchweld vs glass.Would that effect its performance in a roll of situation for windshield retension?

The 3rd question would be a illustration that is not numbered.I believe its a underside molding installation that has the v bead urethane directly underneath the molding?That would be a unsafe installation due to the urethane contact surface is all molding.Unless the part is a PAAS part.The description only has spacer and protuberance and lip.


I would also like to mention that an additional benefit of a v bead is that it help reduce air pockets in the urethane will gunning.

Re: Round bead vs V bead

What is a will gunning?

Re: Round bead vs V bead

Lee
What is a will gunning?


LOL....when

Re: Round bead vs V bead

I actually met a autoglass adhesive sales rep from a large chemical company that I had a conversation with at a bbq that told me that the way 95% of installers shoot v beads, it uses significantly more urethane than a round bead. And while there was some evidence that air pockets were less prevelant in v bead applications, he gave me a wink wink nod nod that they push vbead so aggressively because it moves more product. The guy was a little tipsy when we had this conversation, so I dont really know what to make of it

Re: Round bead vs V bead

I have been doing this a long time. I have used the V, The notch, and the tried and true round. I will say I get zero warranty issues with round beads and V beads have issues from time to time. It seems the round will consistantly make contact with the glass even when the glass is not perfect. I cant tell you how many v bead installs I have removed that either were not touching the glass or barely touched.
Does a V bead use more glue, Possibly. Is it safer? doubt it.

Re: Round bead vs V bead

I disagree. I think the v uses less urethane and performs better.

Re: Round bead vs V bead

It may use less glue depending on the V or how big of a round bead it is. As far as performance? Well that depends if it makes proper contact with the glass. Alot of the jobs I go out on that have had V beads barely touch the glass. Every job I go out on that has had a round bead has a wide glue bead on the body and glass. I have yet to hear of any lawsuits saying a round bead failed, Doubt I will.

Re: Round bead vs V bead

All auto manufacturers use v beads on the glass. We do the same and it looks just like factory when you take it apart again. Many of our competitor's jobs look like a 5yr old ran the adhesive, but then most of them shouldn't be allowed to use a caulk gun in the first place.

This is a no brainer. Follow the auto manufacturers recommendations.

Re: Round bead vs V bead

I was training technicians for various urethanes when the V-Bead came to market.

It is VERY apparent that the V-bead is applied with FORCE to the substrate verses the round bead laying upon it.

This occurs when the caulking gun is held at a 90° angle to the substrate and the pressure on the urethane as it travels down the nozzle has to divert 90° to exit the V-notch of the nozzle.

This application "wets" out the surface with the adhesive and provides a better opportunity for bonding.

The round bead can and does trap air, the V-Bead does not.

It is more difficult to apply a V-bead to the body of the vehicle so most apply it to the glass for this reason.

"A true professional is one that is willing to continue to learn his trade, to not be content on what he knows, but what he can learn."

Re: Round bead vs V bead

I agree Rick. Case in point, look at the May/June 2012 AGRR magazine on page 37. The gun is being held incorrectly, and my 10 yr old grandson could run a better v bead. So much for Auto Glass Safety Council.

Re: Round bead vs V bead

Maddog,
Agreed, I also don't agree with their ad showing a long knife for trimming the urethane. I know it is an accepted method, but it leaves a lot of opportunity for damage and injury.

Re: Round bead vs V bead

I was raised on the round bead but have been using a V-bead for 10 years if not more, It started out being policy back then at Safelite but Ive come to think its better as time goes on. GBG

Re: Round bead vs V bead

The only way to answer these questions is to go back and do an autopsy on each individuals work. Some people are comfortable with certain tools and or methods ....., are they effective? God doesn't have to be the only one who knows.

Re: Round bead vs V bead

Cut some DS glass and do your own test.

I use to have 2" squares of DS glass in my shop. I would gun a bead of urethane on one piece and place another on top and deck it down. Then gun the car.

I had a cured sample to show the customer when they came in so they could compare the samples by twisting the two pieces of glass, fully cured and what the urethane on their car was like at the moment. Convinced them to wait if they wanted it right away, or showed how firm the urethane was when they picked it up. Also, scribed the glass with a glass cutter and then cut it apart with a razor blade to show them the curing process going on inside the bead.

Also, showed how the bead was shaped and contact with the glass.

Re: Round bead vs V bead

xs
Bob Barenek,

I have several questions about the article you wrote.


The 1st question is the contact bonding area of a round bead vs V bead.In your illustrations.You state that round bead will squeeze oval in the best case scenerio.Would the type of viscosity urethane have a determining factor?Example would a low viscosity product squeeze flat instead of oval according to decking height?Also when using a low viscosity product the v bead can not support the weight of a windshield to get the required decking height of a metal clip molding or a encapsulated windshield?

The 2nd question would be pertaining to the lap shear psi to contact surface area of a v bead versus round bead.This is of course depends on the viscosity of the urethane used.While the v bead you illustrated has a larger contact surface on the pinchweld vs glass.Would that effect its performance in a roll of situation for windshield retension?

The 3rd question would be a illustration that is not numbered.I believe its a underside molding installation that has the v bead urethane directly underneath the molding?That would be a unsafe installation due to the urethane contact surface is all molding.Unless the part is a PAAS part.The description only has spacer and protuberance and lip.


I would also like to mention that an additional benefit of a v bead is that it help reduce air pockets in the urethane will gunning.


xs - First question, obviously low vis urethanes will oval out more. The illustrations I used in my blog were to demonstrate the way the geometry of the beads would react to pressure (decking). A round bead could eventually reach the width of original bead but it would use much more product to reach that point and lay too flat allowing for molding misfit or whistle.

Question two. Good question. The oval bead would have to be very wide to reach the OE bead width and be quite low in relation to OE height. This would not allow the urethane bead to bend and stretch in relation to body flex. The purpose of the configuration of a urethane bead in relation to OE design is to allow for body flex over the roadway without undo stress to the glass part. That is why the urethane has the unique specifications for automotive use.

Question three. I'm sorry i didn't number the pictures. The final picture is a PAAS illustration used in a court case I was in. I thought it showed the "V" bead better than some others. I should have qualified that in my article.

I hope this answers your questions correctly. If not try to rephrase.

Re: Round bead vs V bead

Scott
I actually met a autoglass adhesive sales rep from a large chemical company that I had a conversation with at a bbq that told me that the way 95% of installers shoot v beads, it uses significantly more urethane than a round bead. And while there was some evidence that air pockets were less prevelant in v bead applications, he gave me a wink wink nod nod that they push vbead so aggressively because it moves more product. The guy was a little tipsy when we had this conversation, so I dont really know what to make of it


I used round beads in the old days and I thought it used about the same.

Re: Round bead vs V bead

Not sold on the V
I have been doing this a long time. I have used the V, The notch, and the tried and true round. I will say I get zero warranty issues with round beads and V beads have issues from time to time. It seems the round will consistantly make contact with the glass even when the glass is not perfect. I cant tell you how many v bead installs I have removed that either were not touching the glass or barely touched.
Does a V bead use more glue, Possibly. Is it safer? doubt it.


The success of round or "V" beads all depends on the height and width of the bead. If the bead is high enough or if the round bead is big enough, the bead will contact the glass and sealing will be a success. The point, though, is performance, appearance and bonding strength. Both beads will seal.

Re: Round bead vs V bead

Under SC law we trust!
It may use less glue depending on the V or how big of a round bead it is. As far as performance? Well that depends if it makes proper contact with the glass. Alot of the jobs I go out on that have had V beads barely touch the glass. Every job I go out on that has had a round bead has a wide glue bead on the body and glass. I have yet to hear of any lawsuits saying a round bead failed, Doubt I will.


Many installers use the pre-cut "V" bead tips and assume that the tip is good for all vehicles. It is not. The tip of the V must be equal to or higher than the wall of the pinchweld and equal to or higher than the height of a clip on clipped moldings. If not, the glass may not touch the bead.

I have been the witness in several law suits where the round bead failed or did not touch the glass surface. One was the Hawaii suit where a car rental customer died due to the improper installation of a windshield.

Re: Round bead vs V bead

maddog
I agree Rick. Case in point, look at the May/June 2012 AGRR magazine on page 37. The gun is being held incorrectly, and my 10 yr old grandson could run a better v bead. So much for Auto Glass Safety Council.


I'm assuming you meant May/June 2012 because 2011 there was no picture of gunning urethane. In defense of AGRR magazine, some of the pictures that sneak through are chosen by journalists and not auto glass professionals. Also, AGRR magazine is not affiliated with AGSC. AGRR magazine is just out industry's trade magazine and nothing more.

Re: Round bead vs V bead

I know I have been commenting a lot on this subject today but I have been out of town and was unable to comment as these posts were made. I appreciate all of your comments and I thank you for reading my blog. The versus articles were meant to provoke discussion and I am trying to give my readers the reasons, both pro and con, on issue that have been discussed for years. My last point on Round versus V beads is that over the forty years I have installed, I have noticed a huge reduction in water leak complaints. It could be due to better training. It could be better tools. It could be better adhesives. Or, it could be the wider use of the V bead. Rick nelson mentioned that be had created a sample of v vs round beads and so have I. I know that the V bead is more forgiving in relation to crooked or variable height applications because I did dissect many an installation. But I also know many technicians that use a round bead and have had success because they know how to apply it. As a trainer, I use the easiest method to achieve the ultimate goal of safe solid leak-free installations and that is the V bead. And those of you out there that have never used a V bead, I urge you to give it a real good try before completely discounting it.

Re: Round bead vs V bead

"Question two. Good question. The oval bead would have to be very wide to reach the OE bead width and be quite low in relation to OE height. This would not allow the urethane bead to bend and stretch in relation to body flex. The purpose of the configuration of a urethane bead in relation to OE design is to allow for body flex over the roadway without undo stress to the glass part. That is why the urethane has the unique specifications for automotive use."

Most urethane has a tensile strenght on the average about 620 psi when cured.With the v bead that was illustrated #2 it was showing more contact surface on the pinchweld versus the glass.Is that normal?We had several jobs that we redone for road hazzard replacements and the beads on the glass is the same width as the bead on the pinchweld.We apply the adhesive on the glass.With that being said would that installation be compromised because of the less urethane contact surface on the glass?

We rarely use the pre cut v nozzle from the factory.We have a set of three sizes of v notchers.You can custom the height and the width of the bead to the vehicle.

We also use a square bead on certain european vehicles due to the narrow pinchweld where high module urethane is required.The square bead doesn't ooze as much into the interior.The square bead is like its cousin the v bead but its square on the top and bottom.

I was following the case in Hawaii.Its been some years ago.But I do recall also the rental car company rented the car right out after the installation was done.They didnt allow for any SDAT either.They also question here about her blood-alcohol level.This was a disaster waiting to happen.

Re: Round bead vs V bead

Well all of you armatures can step aside and let a real pro post here. We use a parabolic Isosceles parallelogram bead and it has never failed us. Step up to the plate and use a pros bead. Bead that as it may.

Re: Round bead vs V bead

Big JOE
Well all of you armatures can step aside and let a real pro post here. We use a parabolic Isosceles parallelogram bead and it has never failed us. Step up to the plate and use a pros bead. Bead that as it may.


Well, Joe, we've been using spiral dodecahedron beads with a multifaceted interdimensional circumference and we haven't had any leaks in this universe (we can't account for any parallel universes, however).

As long as you present your bonding surfaces perpendicular to the hypoteneuse of the cross-section of the bead, a triangular bead is the best bet in any circumstance.

Re: Round bead vs V bead

Have not rolled a DOG LOG since back in the days of butle. But we always layed the backer thane as a V. Since thane started we have always used the v bead. About 3 sizes handles all jobs. Small Medium , and large. V-bead all the way.

Re: Round bead vs V bead

Big JOE
Well all of you armatures can step aside and let a real pro post here. We use a parabolic Isosceles parallelogram bead and it has never failed us. Step up to the plate and use a pros bead. Bead that as it may.


I have to try that one. Can you draw a cross section configuration for me and tell me how you cut the tip for that?

Re: Round bead vs V bead

xs
"Question two. Good question. The oval bead would have to be very wide to reach the OE bead width and be quite low in relation to OE height. This would not allow the urethane bead to bend and stretch in relation to body flex. The purpose of the configuration of a urethane bead in relation to OE design is to allow for body flex over the roadway without undo stress to the glass part. That is why the urethane has the unique specifications for automotive use."

Most urethane has a tensile strenght on the average about 620 psi when cured.With the v bead that was illustrated #2 it was showing more contact surface on the pinchweld versus the glass.Is that normal?We had several jobs that we redone for road hazzard replacements and the beads on the glass is the same width as the bead on the pinchweld.We apply the adhesive on the glass.With that being said would that installation be compromised because of the less urethane contact surface on the glass?

We rarely use the pre cut v nozzle from the factory.We have a set of three sizes of v notchers.You can custom the height and the width of the bead to the vehicle.

We also use a square bead on certain european vehicles due to the narrow pinchweld where high module urethane is required.The square bead doesn't ooze as much into the interior.The square bead is like its cousin the v bead but its square on the top and bottom.

I was following the case in Hawaii.Its been some years ago.But I do recall also the rental car company rented the car right out after the installation was done.They didnt allow for any SDAT either.They also question here about her blood-alcohol level.This was a disaster waiting to happen.


Did you stomp the auto glass guru xs?.I don't see a reply.lol

Re: Round bead vs V bead

I'm guessing, at this point that some may have a proprietary method, short of the actual factory robot, for performing, meeting or exceeding, blah, flip it over three times with no seat belt, blah, ETCETERA CUBED .

Re: Round bead vs V bead

I've seen tons of both beads. The bead is only as good as the preperation done before applied and the person applying it.
JMO

Re: Round bead vs V bead

"Most urethane has a tensile strenght on the average about 620 psi when cured.With the v bead that was illustrated #2 it was showing more contact surface on the pinchweld versus the glass.Is that normal?"

xs - I think the lap shear strengths are about 620 PSI and the tensile is a little higher but that doesn't matter. The V bead in the illustration is more reminiscent to applying the urethane to the body and not the glass. So it is normal if that is the application chosen. However, the illustration is just a drawing and the amount of adhesive to glass when applying to the body depends on the height of the bead when applied.

"With that being said would that installation be compromised because of the less urethane contact surface on the glass?"

Typically, we apply more urethane than the OE on average and the urethane is stronger than what is necessary for FMVSS compliance. A few less or more millimeters of bond is not going to compromise the bond that much in terms of width or height. We want the OE replicated as close as possible so assure the best result.

"We rarely use the pre cut v nozzle from the factory.We have a set of three sizes of v notchers.You can custom the height and the width of the bead to the vehicle."

Perfect. That is more or less what I do.

"We also use a square bead on certain european vehicles due to the narrow pinchweld where high module urethane is required.The square bead doesn't ooze as much into the interior.The square bead is like its cousin the v bead but its square on the top and bottom."

On VWs or Audis that have real narrow pinchwelds I apply to the glass. Square beads will bond OK but bubbles can occur between the surfaces and not be squished out. They're more susceptible to leaks because of blow out.

The Hawaii case was really a weird case. She did have some wine but it was determined that she was not drunk but rather lost and unfamiliar with the road she was on. The windshield was close-cut twice before and the round bead was not touching the glass in over 60% of the perimeter. It was never determined whether that was due to pre-mature release of the vehicle or whether the installer failed to correctly install the glass.

Re: Round bead vs V bead

Sglass
I've seen tons of both beads. The bead is only as good as the preperation done before applied and the person applying it.
JMO


Agreed.

Re: Round bead vs V bead

Bob,

Thanks for addressing my concerns...Again keep up the good work...

Re: Round bead vs V bead

So shooting a round bead on top of the old kit will cause leaks?

Re: Round bead vs V bead

short cut
So shooting a round bead on top of the old kit will cause leaks?


May not cause leaks. May just cause alot of hurts & deaths.

Re: Round bead vs V bead

Sglass
short cut
So shooting a round bead on top of the old kit will cause leaks?


May not cause leaks. May just cause alot of hurts & deaths.


So shooting a vee bead on top of the old kit is better?I will try that instead

Re: Round bead vs V bead

short cut louie
Sglass
short cut
So shooting a round bead on top of the old kit will cause leaks?


May not cause leaks. May just cause alot of hurts & deaths.


So shooting a vee bead on top of the old kit is better?I will try that instead


For info on shooting v bead on top of old kit, see shooting round bead on old kit.

Re: Round bead vs V bead

you said you were a witness in cases where round beads failed....how....then you state the round bead didn't touch the glass...if thats the case the round bead didnt fail...it wasnt large enough to touch the glass correctly....big difference...ive seen v beads not touch the glass or sub straight correctly .....

Re: Round bead vs V bead

V is the only bead that doesn't incorporate air into the bead.
Or when done correctly allow the bead to stretch.

round may seam it should be better but it isn't recommended in any training
by makers of the urethane.

Re: Round bead vs V bead

⭕️ Or V has a lot to do with the shooter. Seen good & bad in both. Shot ⭕️ For 40+ years. On repeat customers didn’t see issues with bead shot.

Re: Round bead vs V bead

We stopped using round beads 25+ years ago because on repeats there were pockets of air. We have applied a continuous v bead on the windshield since then and repeats look like factory beads.

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