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what is meant by the term ``Primerless to glass``

I have been Auto Glazing for 30 years , used all of the Major Adhesive brands on the Market .Recently I tried a product which is advertised and according to the manufacturers comments in their T.D.S that the product will bond to glass ``providing the glass /frit is clean and free of contaminates ie silicon , wax and or any other contaminates from windshield manufacturing ``( and yes wet scrubbing normally sorts this problem out )

I subsequently tested this product and found that it had a total bond failure , not a weak bond but totally failed . I called the Rep up and expressed my concerns as this product was gaining popularity and I was concerned that the product was not Primerless but in fact needed a surface primer to allow adhesion .

His response was that it was primerless meaning it did not need a ``paint based primer (black out primer as all manufacturers provide for glass , body and plastic /rubber substrates , He then moved on to say that using Activator has to be used to `help ` with adhesion and that everyone know you should use Activator ( even though it is not mentioned at all on the application process in the T.D.S .My Question is this, according to their reasoning Activators are not Primers ????Yet for many systems now the use of Activators is critical ..........no activator no bond !!
After some heated debate and not being able to come to some clarity regarding what a primer is and what it is not even though any dictionary or chemical suppliers will generally refer to Primers by definition as surface modifiers allowing the substrates to be chemically modified to provide adhesion( as is with many automotive painting systems) , In other words primers provide a surface for many adhesives to bond properly particularly Polyurethanes that are high Viscosity( really thick ) and reduced levels of solvents which often offers self prepping and priming advantages . My Question is `what is the general definition of a primer ??? if it is a product that provides a surface for bonding ?? Is an activator a primer seen as it is a chemical deposited on the surface of the glass for bonding ??

Re: what is meant by the term ``Primerless to glass``

An activator is not actually for the purpose of preparing a substrate for bonding but for activating the catalysts within the urethane to start the curing process especially in some of the newer urethanes with faster so-called safe drive away times. Without the activator, the urethane does not cure properly and thus will fail.

Re: what is meant by the term ``Primerless to glass``

If you press Rep. You will be told "they don't accept liability if you use the product without a primer". So how can it really be primer less to glass?

Re: what is meant by the term ``Primerless to glass``

It means less time with the family while your prison sentence time runs out!

Re: what is meant by the term ``Primerless to glass``

This looks like a great subject for my next blog.

First of all, I am assuming that we are talking about Sika products. The Aktivator used by Sika, as told to me by past chemical engineers, is more of a prep than a primer. In other words, more a cleaner than a product that modifies a surface "...allowing the substrates to be chemically modified to provide adhesion( as is with many automotive painting systems)". It is why that their Aktivator is used to clean and prep other surfaces. It works great for cleaning off urethane or body primer from a painted surface.

Primerless to the glass, as used by other adhesive manufacturers, truly means that no other surface material is added to the glass surface except to clean it according to the manufacturers' written instructions. If Sika in their written instructions "clean" the glass by applying their Aktivator in the final step of cleaning, then that is what one must do to assure proper bonding. If the Aktivator does not truly meet the definition of a "primer", then the adhesive is by definition "primerless". I will admit that it is confusing and could be argued that it is a play on words. The facts by definition is sound.

The Technical Data Sheet, no matter what brand, is not considered the written instructions for use. Dow and Sika have written instructions and in some cases written manuals for proper use of their products.

Re: what is meant by the term ``Primerless to glass``

In chemistry, the definition of an activator is: a substance which initiates or accelerates a chemical reaction without itself being affected.Since the newer advance cure urethanes are RINAS(reinforced isotropic network adhesives), it is my understanding that the activator is for the purpose of initiating this chemical crosslinking process in order to achieve a faster safe drive away time, even though I believe a vehicle is not truly safe to drive until the urethane is fully cured and that takes far more than an hour! If an activator is a cleaner, why not call it a cleaner?

Re: what is meant by the term ``Primerless to glass``

I would guess that the actual product, Aktivator, does not meet either definitions. By the sound of your response, you are far more knowledgeable on this issue than I. So I am not one that can be definitive on this subject. I would advise talking directly to a Sika rep. that is familiar with the chemistry.

Re: what is meant by the term ``Primerless to glass``

Old glass guy, so how long do you make a customer wait to drive? Full cure can take 5-10 days depending on weather, bead size etc. Have you seen Sika's crash test video? I have, pretty impressive actually, Ford Focus 30 MPH, 60 minutes after BEGINING to apply Urethane into a concrete barrier. Ben, As for the Primerless application, I thought is was automatic that everyone knew that the glass must be cleaned, prepped with Aktivator for proper adhesion and retention..... I understand your question but I'm scratching my head as to what your point is. Primer would be some sort of a paint, Aktivator is a cleaner and adhesion promoter. (Lehmans terms). If your wanting a cheap Primerless thane (not sure why anyone would) then I think Dow 418? 428? Would be what you want. Even the Sika Titan P2G+ needs Aktivator for a RELIABLE bond. I guess I've never understood why Primerless thane is in demand, it takes longer to cure, generally it doesn't deck as well due to the primer being mixed in with the urethane making it thinner in consistency, and usually isn't as firm when cured giving the vehicle less rigidity. With the new thanes on the market cost of a quality thane that requires a primer or Aktivator isn't much more and is much much much better for the install and customer. The priming step literally takes as long as walking in a circle around the glass.....

Re: what is meant by the term ``Primerless to glass``

T1, according to DOW, their urethanes, including Betaseal One, Express and 418, fully cure within 24 hrs. @72 degrees and 50% humidity. Here in Florida that's pretty much everyday. The SIKA products such as ASAP+, Mach30 and Mach60 take up to a full week to fully cure at those temps. The SIKA test videos are pretty impressive, however leave out one very important detail, FMVSS216, roof crush resistance. Since the windshield is designed to help support the roof in the event of a rollover, I believe that would require full cure. If a vehicle cant pass FMVSS216, then how can it be safe to drive? Now if your talking about a customer driving home at 30 mph, where there is less of a chance of a rollover, then maybe ok, but can you guarantee the customer is going to do that?

Re: what is meant by the term ``Primerless to glass``

I've used CR Laurence's 300 Series Primerless and never have had a problem.

Re: what is meant by the term ``Primerless to glass``

Full cure? Have you not done a dealer job on a brand new unsold vehicle with wet core? No urethane manufacture can roll test every vehicle. You can reach 600,700,800 pounds per sq. inch without full cure. SDAT is not predicated on full cure.

Re: what is meant by the term ``Primerless to glass``

First of all, all of the urethanes that I have seen at the SDAT are at 150 psi, not 600,700 or 800. According to SIKA, their urethanes, including ASAP+, Mach30 and Mach60, under most conditions, form a 1mm skin at the SDAT and about an 1/8 inch membrane after 24 hours. That information came directly from a SIKA senior application engineer. I hardly believe that is enough to help support a roof in a rollover! Have you ever heard of cohesive failure? Cohesive failure is the inability of an adhesive to resist internal separation. The number one cause of cohesive failure is uncured adhesive. If the urethane is not fully cured, it is subject to failure.

Re: what is meant by the term ``Primerless to glass``

all of that may be true with Sika products, but I can also tell you that Dow isn't any faster. They do NOT achieve 100% full cure in 24 hrs. doubtfull in 96. Do a test. take the next two old windshields you replace, clean the outsides very well. use appropriate primes, cleaners. run a bead of Dow at the top and Sika on the bottom, invert the second glass and set it on top. leave overnight, or even the weekend. you will see. Keep it honest run equal bead sizes and equal products, express with mach 60 dow one with mach 30 etc.

Re: what is meant by the term ``Primerless to glass``

Actually, I have tested the DOW products that I use and they do in fact fully cure within 24 hours here in Florida, at least most of the year. For instance, tomorrow the forecast is 86 degrees with 72% humidity. The curing agent for all urethanes on the market is atmospheric moisture, so we have an advantage with that here in Florida. I have not tested the SIKA products, however, but have done much research on them. I personally would not use them, not only for the cure time, but mostly due to the health warnings, especially on the Aktivator, but that's just my choice.

Re: what is meant by the term ``Primerless to glass``

Lets not forget the fact, primer is black to block uv rays. If you have a w/s with a fruit that lets sunlight in the bond from glass to urethane will break down. How do you stop that with a clear activator?

Re: what is meant by the term ``Primerless to glass``

Ooops, You don't!
Ooops...again

Re: what is meant by the term ``Primerless to glass``

old glass guy
An activator is not actually for the purpose of preparing a substrate for bonding but for activating the catalysts within the urethane to start the curing process especially in some of the newer urethanes with faster so-called safe drive away times. Without the activator, the urethane does not cure properly and thus will fail.

I hate to tell you, but you are 100% incorrect on that one. The activator has EVERYTHING to do with preparing the surface for adhesion and NOTHING to do with starting the curing process. Single component urethanes are temperature and moisture cured products, when you shoot it out of the tube, the air has moisture in it and the curing process begins, the more moisture, the quicker the cure rate. If you have low levels of or no moisture, virtually no curing will take place. Now take a urethane that is a 2K product, one that has a urethane part and a curing agent mixed together, it will cure via a chemical reaction, probably give off heat and be totally cured in what ever the product specs indicate, regardless of temperature or humidity levels. BUT, they both will cure. NOW, if an activator is required and you do not use it, they both will cure, no doubt, but they only will adhere to the glass surface when the products are in the wet stage. When they cure, and they will, even without activator, they will not adhere to the glass surface. Sorry.
Ooops...

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