Large pit failing

[SGT]

Good points Gohst rider,

Since we know the main body of the repair has been previously done, and we know that Jeff is using DKI pit resin, I would say 2 min since it is just the pit he is re-doing becuase we do not know what type of curing lamp is being used or the strenghth of the bulb.

If he was doing the full repair from scratch I would say 5 min cure time.

[Brent Deines]

I agree with SGT "if" you are using a good 12V or 115V light 2 minutes is what I recommend since the break has already been fully cured and you are only curing the pit area. If you are using a battery operated light I would still cure for 5 minutes. This is probably over kill since you are not curing through any solar green glass and the maximum depth of the pit can be no more than 3mm at the very most, but better safe than sorry.

If the pit resin is fully cured it should be able to stand up to very aggressive scraping. I tend to press pretty hard when scraping off the cured pit resin, and always use a new blade.

It should be noted that other brands of resin may cure faster or slower, so you should always follow the manufacturer's recommendations. However, it is important to note that some resins cure too quickly. We once formulated such a resin but found that because it skinned very quickly the deepest point of the resin actually took longer to cure properly. Ideally you want the resin to cure at a rate that allows the inside to cure at approximately the same rate as the outside.

While the time necessary for the resin to cure fully is highly dependent on the resin as well as the light source used, allowing enough time for the resin to cure long enough for it to be solid all the way through is very important, which is why Delta Kits advocates a bit longer cure times than necessary. We try to take as many variables into account as we possibly can.

[tooldini]

Thanks guys and there were no rain-x type products used and this was the first time I wiped with alcohol. I cured it for around 5-6 minutes. I set my timer for 5 mins,, but left it on longer than that. It seems to be a problem here in michigan, I do see many old repairs from other techs with pits not in or looking very old and ready to fall out. I do want to figure this out I appreciate all the help and and going to use all the techniques till I find the right combo.

Jeff

[GlassStarz]

I know I saw a bunch in Vermont I think the extreme temp changes were the cause below freezing then warmed by the defroster over and over goin from 20 below zero to warm 3 times a day has to take a toll. I havnt noticed many here in Fresno so it must be the hot weather dosnt affect things as much? Brent is the guy who knows the science of the resin and its properties but that damn cold has to be partialy at fault

[Brent Deines]

Well I'm no chemist, but I do have the benefit of talking to chemists and engineers a bit more often than the average windshield repair technician.

Having started in Eastern Montana we saw our share of below 0 and 100+ weather. In my opinion it is much easier to get good results in the hot weather than in the cold weather, but I can't say that I had any problems with pits following out. I did see a lot of repairs made by my competitors that looked terrible, but I see that here in Oregon and everywhere else I travel as well.

I have tested a lot of resin over the years and some of it has very poor adhesion to the glass. I've even tested some pit resins that pulled off with the curing tab rather than sticking to the glass, but I would say that most of the resins sold by the major manufacturers have gotten much better over the years.

All resins shrink as they cure, but some shrink much more than others. Since resins are acrylic based, they will all discolor over time, just as cast acrylic will when exposed to the elements, although there again, some hold up much better than others. In addition to these factors, windshield repairs are exposed to sun, rain, ice, wiper wear, dirt, sand, car wash chemicals, etc., which all eventually discolor the pit area and wear down the surface, but it should take months or years to see a significant change in appearance depending on the conditions the windshield is exposed to.

So although some discoloring and wear in to be expected over time, I'll say it again, I have never had the pit fall out of a completed repair regardless of weather conditions. In addition to my personal experience, I speak with customers every day who repair windshields in some of the coldest regions of the world with excellent results, so I am quite confident that unless there is something on the windshield, or the resin has been contaminated somehow, the pit will not fall out, ever.

Although many windshield repair technicians buy resin based on price only, there are significant differences that affect how your repairs will look months or years down the road. However, as stated previously, over time the appearance of any repair with a large pit will change. When this happens the repair can be resurfaced. To do this all you need to do is remove enough of the pit resin to get rid of the discoloration and any dirt that may have been embedded in the surface of the resin. As noted previously in this thread, use a drill or probe to clean the pit area thoroughly, apply a thin coat of low viscosity resin to wet all the scratches left by the drill or probe, apply a drop of pit resin, cover with a curing tab, cure, scrape and polish. The result should be a complete cosmetic restoration of the repair. This process is very much like restoring a headlight or even the filling of a tooth; the longer you wait the deeper you will have to go to remove the discoloration. However, the nice thing about windshield repair is that you can actually drill out the entire pit area and cap it with new resin without compromising the integrity of the repair. It's purely cosmetic.

Keep in mind many technicians don't use pit resin or pit polish at all, so many of the repairs you see have never been filled to the surface or in my humble opinion, properly finished. A good pit resin is much harder than most low viscosity resins used to fill cracks and the main body of the break. That resin needs to be more flexible than hard, but pit resin needs to be hard for increased resistance to surface wear and exposure to elements.

Jeff, did you ever test the pit resin? Although unlikely, it is possible the resin was contaminated. We keep our work environment pretty clean when filling resin bottles, but we by the bottles 10,000 at a time and they are shipped to the printer before we ever see them, so there is always a chance that something was introduced to the bottle before it was filled. If there is something wrong with the resin we obviously want to get it back and test it, and will of course replace it for free.