How to get rid of moisture in legs of star break?

[Brent Deines]

You are absolutely right Glasseye, not all factory installations are perfect, but in my experience underpaid, overworked aftermarket installers make far more mistakes than the factory robots. this just reiterates CV's point that an installed glass may have more stress than an uninstalled glass.

It seems we are getting off topic once again. Sorry for my part in that.

[t4k]

You are absolutely right Glasseye, not all factory installations are perfect, but in my experience underpaid, overworked aftermarket installers make far more mistakes than the factory robots. this just reiterates CV's point that an installed glass may have more stress than an uninstalled glass.

It seems we are getting off topic once again. Sorry for my part in that.

OEM glass installations may not be perfect but a robot installation in a controlled atmosphere is much more accurate than two guys in a parking lot. The defense rests...

[BrightFastWSR]

Brent, have you ever measured the heated area by a Drystar right away after heating about 20 seconds ? What was the temperature you measured? Thank you.

Yes I have measured the heated glass but I can't really give you the answer you are looking for due to the number of variables involved. Here are a few...

1) Temperature of the glass prior to applying the moisture evaporator. We did a test this morning starting with a glass temperature of approximately 76 degrees and after the moisture evaporator was applied for 20 seconds we got an average glass temperature reading of 140 degrees. We did the same test but this time preheated the glass to 125 degrees, then applied the moisture evaporator for 20 seconds. This time we got an average glass temperature reading of 197 degrees. Never did the glass temperature reach 212 degrees, but the water did begin to bubble in 10-12 seconds and was gone in 16-17 seconds. The interesting thing to note here is that heating the glass to 140 degrees with a hair dryer did not remove the water from the break but heating the glass to 140 degrees with a moisture evaporator did! I'm sure there is a good explanation for that but I have to admit I don't know what it is.

2) It is very difficult to get an accurate reading of the glass temperature of glass using an infrared thermometer. An inexpensive infrared thermometer is fine for finding an acceptable temperature range, but readings are not consistent enough for serious glass temperature testing, especially at hotter temperatures. In our testing we used an inexpensive model (under $50) and a mid-range model (under $150). They were close at lower temperatures but over 200 degrees the variance became increasingly significant. Even the better model failed to produce consistent results in repeated tests.

3) I have two technicians do the testing and while their results were similar, they were not identical. I would guess no two people will get the same results with these unsophisticated testing methods.

4) We tested several different moisture evaporators and each one performed slightly differently. We tried to measure the heating elements with the infrared thermometers but the results were extremely inconsistent. We did however get consistent temperature readings far in excess of 212 degrees with both thermometers. Again, I just don't think an infrared thermometer is well suited for this purpose and we do not have another way of testing the actual temperature of the heating elements at this time, but in every test the water began to bubble and then disappeared within the recommended 20 seconds. Perhaps it is the heating element in proximity to the moisture in the break that is the most important factor in the successful removal of moisture.

A heat gun most certainly produces enough heat to get the water in a break to boil, as does a torch. We don't recommend a heat gun because there are even more variables that come into play. There's just no way for us to tell a technician what heat setting to use, how far from the glass to hold it, or how long to leave it on the glass. The same is true for torches, plus using an open flame brings up additional safety issues. That's not to say you cannot use these tools to remove moisture, but just that I believe the moisture evaporator is a safer option.

We did have one very unexpected result in our testing today. We wanted to see how hot we could get the glass with our blow dryer and if we could actually dry out the break with it. In my previous tests it took so long that I finally gave up without ever getting all the water out, but today we used a very powerful blow dryer and placed it directly on the glass over the break to see what would happen. The glass temperature reached 170 degrees and although the water never bubbled, after 8 minutes it did evaporate. So I have to retract my previous comments about it taking all day to remove moisture with a blow dryer. Given the choice of 20 seconds vs 8 minutes to dry out the break I would still opt for the moisture evaporator, but depending on the model used it is obviously possible to dry out a break using a blow dryer (without taking all day). My apologies to those I have told it could not be done. Still learning!!!

One other unexpected result from our testing today was that the glass did not crack during any of our moisture evaporator tests. The combination break that we dried out using the blow dryer also did not crack out, but a nearby star break did crack out before we could get the moisture out using the blow dryer. The glass cooled much faster after using the moisture evaporator than it did after using the blow dryer because the blow dryer heated a far larger area of the glass. Also worth noting, was that the inside of the glass got hotter using the blow dryer than it did with the moisture evaporator. One or both of these factors may have contributed to the star break crack out but that is only an assumption. We would need much more testing to verify.

All temperatures readings were measured in Fahrenheit.

Here below is my test result which makes me frustrated:

These are the equipments I use to evaporate the moisture inside the break:
a 1500w heat gun, an electric temperature detector specialized in detecting surface temperature


I use the heat gun to heat the leg pointed in the following picture for 8 times, each time I have heated it to 221~230 F, each time this leg disappeared when the windshield got hot, each time it showed as the following pic. when heated area cooled down at temperature 82F. although the 8th time I had kept the temperature of that area over 212F over 2 minutes.


However, when I just slightly pressed that area with a scribe, the break showed again. When I release the pressure, the break dissapeared again. Does it mean that the moisture still in there to make the break unseen when releasing the pressure on it? If it is moiture, why it can not come out since I have made a small bullseye on one end of the legs and heated the area at high temperature so many times?

[BrightFastWSR]

Brent Deines wrote:
“The glass temperature reached 170 degrees and although the water never bubbled, after 8 minutes it did evaporate. So I have to retract my previous comments about it taking all day to remove moisture with a blow dryer. Given the choice of 20 seconds vs 8 minutes to dry out the break I would still opt for the moisture evaporator, but depending on the model used it is obviously possible to dry out a break using a blow dryer (without taking all day). My apologies to those I have told it could not be done. Still learning!!! ”

I tried to use a hair drier to heat the windshield for 15 minutes for the first time, and 10 minutes the second time,the highest temperature I tested on the surface is around 140F. And then cool down the windshield to 82F, then I press slightly on the break, it showed and not rebound this time.


Thank you, Brent. I still don't know why a heat gun can not evaporate the moisture since it is more efficient to heat the glass. Will test later to see if I can find the reason.

[Brent Deines]

...Thank you, Brent. I still don't know why a heat gun can not evaporate the moisture since it is more efficient to heat the glass. Will test later to see if I can find the reason.

I never said a heat gun could not be used to evaporate moisture! I just said you have to be very careful with it so it is not my method of choice (personal preference). In regards to the rest of your last two posts, what the heck is it you are trying to accomplish? 220+ degrees F for over 2 minuets? It looks like that excessive heat may have cause some delamination; that break is a mess. I can't believe you did not crack out the glass!

When you heat a crack until it goes away all you are doing is expanding the glass until the crack closes. When the glass cools or when you flex it the crack opens back up. What you are experiencing has nothing to do with moisture! I would really like to help you, but I think you are getting so confused, maybe because of all the conflicting advice on this forum, that I don't even know where to begin. It's obvious you are not following Delta Kits recommended practices or taking my advice, so I'll just bow out of this topic and let others try to help you.

I'm sorry to be blunt but for your sake and the sake of your customers you really need to get some training. I wish you the best of luck!

[screenman]

That heat gun will expand the glass from the outside before the water inside gets a chance to boil off, it is a useless piece of equipment in our industry.

Buy the right tools and get some proper training, blunt I know but I am so annoyed at the people making this trade look unprofessional.

[BrightFastWSR]

...Thank you, Brent. I still don't know why a heat gun can not evaporate the moisture since it is more efficient to heat the glass. Will test later to see if I can find the reason.

I never said a heat gun could not be used to evaporate moisture! I just said you have to be very careful with it so it is not my method of choice (personal preference). In regards to the rest of your last two posts, what the heck is it you are trying to accomplish? 220+ degrees F for over 2 minuets? It looks like that excessive heat may have cause some delamination; that break is a mess. I can't believe you did not crack out the glass!

When you heat a crack until it goes away all you are doing is expanding the glass until the crack closes. When the glass cools or when you flex it the crack opens back up. What you are experiencing has nothing to do with moisture! I would really like to help you, but I think you are getting so confused, maybe because of all the conflicting advice on this forum, that I don't even know where to begin. It's obvious you are not following Delta Kits recommended practices or taking my advice, so I'll just bow out of this topic and let others try to help you.

I'm sorry to be blunt but for your sake and the sake of your customers you really need to get some training. I wish you the best of luck!

I also never said that you said a heat gun could not be used to evaporate moiture. At that time I just curious in my mind why moiture didn't evaporate with a heat gun so I just write it down "I still don't know why a heat gun can not evaporate the moisture since it is more efficient to heat the glass". I am sorry if it made you misunderstand about it.

You said that a blow drier can evaporate the moiture when keep it run approx. 8 minutes, I also tested here,it really worked. Thank you very much for your test.

Now in my opinion,a heat gun is not fit to evaporate the moisture, I did make a crack in evaporating moisture in another break I made on my practing windshield, the heat power is too high, so it is very difficult to control. I decided to abandon it.

"It looks like that excessive heat may have cause some delamination." yes, it really cause delamination as I can see some tiny bubbles in it.

[Brent Deines]

...I also never said that you said a heat gun could not be used to evaporate moiture...

Sorry, I misunderstood your original post.

[Glasseye]

You are absolutely right Glasseye, not all factory installations are perfect, but in my experience underpaid, overworked aftermarket installers make far more mistakes than the factory robots. this just reiterates CV's point that an installed glass may have more stress than an uninstalled glass.

It seems we are getting off topic once again. Sorry for my part in that.

OEM glass installations may not be perfect but a robot installation in a controlled atmosphere is much more accurate than two guys in a parking lot. The defense rests...

What would your defence say about this? - http://www.glassbytes.com/fetch.php?url ... ay-moonro/

[t4k]

You are absolutely right Glasseye, not all factory installations are perfect, but in my experience underpaid, overworked aftermarket installers make far more mistakes than the factory robots. this just reiterates CV's point that an installed glass may have more stress than an uninstalled glass.

It seems we are getting off topic once again. Sorry for my part in that.

OEM glass installations may not be perfect but a robot installation in a controlled atmosphere is much more accurate than two guys in a parking lot. The defense rests...

What would your defence say about this? - http://www.glassbytes.com/fetch.php?url ... ay-moonro/

Please clear this question up for me. What does this article have to do with how a W/S is installed?