Chips not filling - Viscosity ratings

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MichaelSmedley
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Chips not filling - Viscosity ratings

Post by MichaelSmedley » October 14th, 2014, 2:06 pm

Id like to ask a question on behalf of a customer enquiry I received the other day.

He mentioned he had been having difficulty with the Magnibond Resin filling some star chips during the winter months and he wondered if it had anything to do with the viscosity. As you guys know the Magnibond has a rating of 18cps.

For the record the climate here is 10/40 Celsius, thats 50/104 Fahrenheit in old money. The lower number being in the winter of course.

I pointed out that the problem could be a number of reasons. Moisture in the chip, temperature of the glass, impact point not scribed enough, rainX, not using enough resin, suggesting he use a moisture evaporator. I also suggested drilling and slide hammer method, however I’m not a huge fan of this method unless its a last resort.

The customer is very open and has taken it all on board and said he will try the above suggestions. He is a very loyal customer and has called to inform us he has been using another local resin brand with a viscosity of 24cps (brand not known). He tells me the problem does not occur with the other brand.

This makes no sense to me as the higher viscosity rating should make the problem worse if any. Who knows, it could be a placebo effect.

In any event the customer really wants to keep using Magnibond and is asking for our help.

I would appreciate any suggestions from the group as I know we are all from different climates. Im sure there is a solution to be found.

Thanks in advance.

PS. The resin is not out of date (by years) and is alway stored correctly.
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Re: Chips not filling - Viscosity ratings

Post by EMCAutoGlass » October 14th, 2014, 4:02 pm

I'm sure a DK representative will weigh in on this topic soon, but I'll offer a couple thoughts. First, all breaks are a little different. Some stars will fill fine with 60 or 90 cps, and some will take an hour to fill with a thin 18 cps. Temperature of the glass will affect it as well. If cold, warm the glass, and if hot, cool it down. A good, clean impact point will assist resin flow as well. Using a scribe or even drill to clean the impact point really helps. The last couple star breaks I did took almost an hour each (I used Magnibond for both). My guess is the legs were REALLY tight. It seems I always have one stubborn leg, and my procedure is to wait it out and continue to flex, run a couple cycles, flex, clean some windows, then come back to it. They all fill 99%+ of the time, and my repairs look outstanding. If I hit an hour with no luck, that's when I reluctantly drill and pop a little bull's-eye (I try to avoid that if at all possible). To get back to the point of viscosity ratings, I highly doubt a resin with a higher viscosity would fill the same leg any better than one with a lower cps. I think a higher viscosity resin filling faster was probably just luck of the draw for that specific break. Really, the difference between 18 and 24 cps is miniscule/negligible. Unless the manufacturer of the 24 cps resin hasn't conducted good testing on their products, or they claim the cps is higher than it really is?

Thanks, and sorry if I told you a bunch of stuff you already know.
-Marty

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Re: Chips not filling - Viscosity ratings

Post by Brent Deines » October 14th, 2014, 5:20 pm

Very well put Marty. I will add that although most people relate viscosity to how thick a liquid is, it is actually by definition "a quantity expressing the magnitude of internal friction, as measured by the force per unit area resisting a flow in which parallel layers unit distance apart have unit speed relative to one another". In other words, the rate at which the liquid flows. Therefore I have to agree with Marty that it doesn't make any sense that a 24cps resin flows into a chip better than an 18cps resin. If a resin flows better in testing it has to flow better into chips and viscosity is the measurement for the rate of flow.

In my opinion an 18cps resin is perfect for the temperature range 10/40 (50/104) temperature range if you are using a Delta Kits injector. In fact, it works very well in considerably colder and warmer temperatures as well. As Marty said, there is very little difference in the flow rate between an 18cps resin and a 24cps resin but in our testing 10-20cps flows noticeable better in cooler temperatures. At 10 (50) temperatures most technicians probably still wouldn't notice much of a difference but the colder it gets the more noticeable it becomes.

I suggest you explain the scientific facts to your customer and then offer to let him try a different product, perhaps a slightly lower viscosity product just in case the 24cps resin is labeled incorrectly. If it truly is an issue of flow rate the lower viscosity simply has to flow better.

Obviously I never like to hear a customer say they think another resin flows better than MagniBond but it is somewhat comforting to know that out of the tens of thousands of bottles of resin we sell each year we only get a handful of complaints and those are most often resolved by offering an alternative product. While I use MagniBond in all temperatures and all break types, we sell a variety of resins for those who desire something different. Different strokes for different folks!

I'll close by saying it is very difficult to change someone's mind if they are sold on an idea or a product, even if you can provide irrefutable facts, so we can but try. If we can be of any technical assistance please give us a call.
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Re: Chips not filling - Viscosity ratings

Post by screenman » October 14th, 2014, 10:13 pm

Adding to this, the thing that often stops a clean dry leg from filling is UV. I would guess that 80% of so called techs out there do not use any UV protection whilst working on a damage.

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Re: Chips not filling - Viscosity ratings

Post by MichaelSmedley » October 15th, 2014, 12:22 am

Thanks for the detailed feedback guys. I will send a link to the topic to our client, I am sure he will find it helpful.
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