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Old 29-06-2013, 17:04   #46
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I worked for a pretty high end manufacturer and we kept cobalt in stock. Because if a layup needed that it needed that. Pretty sure it was common practice at most other places. I don't think that the boats were compromised at all. These things were really well built/overbuilt. If you had 20,000 dollars in a mold and it needed a little boost that happened. How the big production guys dealt with this volatility I don't know but guess they wouldn't hesitate.
Aren't we still seeing chopper gun resin mixed boats being built?
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Old 30-06-2013, 07:04   #47
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Re: Are barrier coatings bogus?

So how exactly do i tell if my boat has a barrier coat?

I've sanded down to bare fibreglass in a few small spots to see what's on there and the 1st layer is a thick light blue coloured layer. I assumed it was gelcoat, but i'm not 100%.
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Old 30-06-2013, 07:32   #48
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Re: Are barrier coatings bogus?

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Originally Posted by Freerider View Post
So how exactly do i tell if my boat has a barrier coat?

I've sanded down to bare fibreglass in a few small spots to see what's on there and the 1st layer is a thick light blue coloured layer. I assumed it was gelcoat, but i'm not 100%.

As long as the area in question is not near a factory light blue stripe, that's probably a vinylester barrier coat.
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Old 01-07-2013, 20:26   #49
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Re: Are barrier coatings bogus?

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You mix the resin a little wrong, the temperature and humidity goes off, someone doesn't clean one roll of cloth or wet it out fully....
In the interest of clarity I wish to add, it's a but more than the "wrong" ratio. Shooting a boat requires a relatively huge batch when compared to, say making a surfboard. Smaller batches, unless gross error, allows more precise control.* A large batch may not even be mixed properly, the beginning of a compound of errors, which means some parts of the batch are "hotter" than other parts. Plus, there is the requirement of labor to apply a large batch. Labor, by and in itself produces error.


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Vacuum bagging probably helps because it ensures a more even wet-out. 100% if done correctly, neither more nor less. And if you go to prepreg, where the cloth is pre-impregnated in a controlled factory...well kaching, but you remove more chances for human error. Remember, in the 70's and 80's it was a rare workplace that did alcohol or drug testing too.
I don't know what "kaching" means but other than that, bingo.

Well, by your reference to drug testing and the sort I gather you insinuate a proportionate share of error could be contributed to drug use. I'm not so sure of that. Batch control was a problem in that time period, hence a source of a myriad of problems. The essence of skilled labor is the use of superior knowledge...knowledge gotten by experience. And this has nothing to so with drug use, et al. Labor oft has had a steep slope to climb in keeping up with technology. Plastic fantastic didn't really catch on until the time period in question and you have the chemical mfgs to thank for that. (if you wish to get down in the dirt about it, there was a short period of leading up to the explosion of FRP in mfg. That period found it's zenith in the '60s.

*Smaller batches do lend to more precise control but only to a point. It is conceivable to mix a batch which demands a very precise measure of parts. In this case, it is better to mix a larger batch which has a greater tolerance for imprecise measuring, by weight or volume, for the intended use.
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Old 01-07-2013, 20:37   #50
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Re: Are barrier coatings bogus?

Oh wait...did you mean "Ka-Ching", to mimic the sound a mechanical cash register made, to signify 'you're in the money', as a euphemism for a job done well?
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Old 01-07-2013, 20:56   #51
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Re: Are barrier coatings bogus?

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In the interest of clarity I wish to add, it's a but more than the "wrong" ratio. Shooting a boat requires a relatively huge batch when compared to, say making a surfboard. Smaller batches, unless gross error, allows more precise control.* A large batch may not even be mixed properly, the beginning of a compound of errors, which means some parts of the batch are "hotter" than other parts. Plus, there is the requirement of labor to apply a large batch. Labor, by and in itself produces error.


I don't know what "kaching" means but other than that, bingo.

Well, by your reference to drug testing and the sort I gather you insinuate a proportionate share of error could be contributed to drug use. I'm not so sure of that. Batch control was a problem in that time period, hence a source of a myriad of problems. The essence of skilled labor is the use of superior knowledge...knowledge gotten by experience. And this has nothing to so with drug use, et al. Labor oft has had a steep slope to climb in keeping up with technology. Plastic fantastic didn't really catch on until the time period in question and you have the chemical mfgs to thank for that. (if you wish to get down in the dirt about it, there was a short period of leading up to the explosion of FRP in mfg. That period found it's zenith in the '60s.

*Smaller batches do lend to more precise control but only to a point. It is conceivable to mix a batch which demands a very precise measure of parts. In this case, it is better to mix a larger batch which has a greater tolerance for imprecise measuring, by weight or volume, for the intended use.


I'll take this opportunity to note some more factors involved, for those who have never built a boat on a factory floor. Chopper guns are too sweet a deal for most builders to pass up, it's why they are still used by many builders. They spray gel in the mold and skin coat it (if its a half way decent build), then build up 1/4"-1/2" of chop. This makes everything which follows much simpler. But it also leads to many problems, aside from the obvious concerns of quality control when applying that much glass so quickly. There are two basic types of chopper gun, external mix and internal mix. Internal mix guns are rare and finicky. They mix the catalyst and resin in the cutter head/gun. This can lead to resin kicking in the gun. For this reason internal mix guns are usually used for molding small parts in large factories having nothing to do with boats. In a boat building setup, external mix is far more common for obvious reasons. It mixes by spraying the catalyst into the resin in the fan as it comes out of the gun. This obviously results in very poor mixing, as there is no actual mixing action. It also results in an extremely toxic workplace, as there is atomized MEKP in the air. Common problems include the gun operator running out of catalyst without noticing, air in the catalyst line when switching containers, poor calibration or a dirty tip resulting in "hot spots" which kick off before being fully rolled out, etc. etc.

Suffice it to say, running an external mix gun is not as precise an art as it should be. It's an awesome tool if you're a boatbuilder looking at cost savings, too tempting for most to resist. But it's full of pitfalls. And of course it's exactly this sort of work that is often foisted off on the cheap labor, because nobody with an education wants to do this sort of thing long term. Cheap laborer who doesn't really care and isn't treated all that great plus external mix chopper gun=blisters! Or worse.
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Old 01-07-2013, 22:18   #52
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Re: Are barrier coatings bogus?

Richard-
"kaching" aka "ka-ching" is the sound of an old fashioned CASH REGISTER BELL which some of us will remember means "that's gonna cost you" or "you just spent money".
So, you want your Rolex to be properly serviced by factory technicians at the actual factory, and turned around within one week including the shipping? KACHING!

As minaret said, and cheechako's mention of NASA and clean rooms...if you have ever used a simple paint gun or airbrush, environmental factors can be a b|tch even with "simple" ink and paint. If you're trying to blend two chemicals accurately, with a physical gun that almost inevitably will now have flow problems on both liquids, and then you factor in environment and the costs of a climate-controlled boatbuilding shed large enough to accomodate multiple hulls, and still bring in some air for the dwarves to breath....
Stop by your local auto body shop and ask them how much fun it is trying to match a real high-flake metallic paint as the environment changes. And that's bearing in mind that now, unlike the 80's, the EPA requires those guys to use closed spray booths.

I think it took 20 years, with mechanics pulling and retorquing the tires on my car to do the annual inspection, before I found ONE shop that properly retorqued them. And that operation involves simply turning a wrench. So, mixing, spraying, cleaning the sizing off the cloth or testing the cloith to make sure it has the right sizing on it? Way more opportunities to screw up, and once it has left the factory, who's gonna know if you screwed up, until 20 years later, when it isn't "your" problem any more?

And I'd bet that as resin and material prices went up, suppliers were cheating too. That's also sadly normal in every business.
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Old 01-07-2013, 22:54   #53
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Re: Are barrier coatings bogus?

Sometime in the late 1970s I walked the yards looking to get on building boats. Most were full up, even the broom pushers. I did get on with a yard that made plastic boats (ewwww yuck, wood being my thing and all). I lasted about one month. Most my time was spent cleaning guns but with a bit of shooting. Keep in mind I was junior, the fresh face. Talk about toxic environment! Anyway, I figured I had learned enough and off I went. At least I gained insight. Ironically, over the next four years I was again working with resins and MEK but in a much more controlled environment.

From what Mineret says I reckon we used internal mix chopper guns. This was Costa Mesa, California so maybe from that you can guess which yard.
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Old 01-07-2013, 23:11   #54
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Re: Are barrier coatings bogus?

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Originally Posted by hellosailor View Post
Richard-
"kaching" aka "ka-ching" is the sound of an old fashioned CASH REGISTER BELL which some of us will remember means "that's gonna cost you" or "you just spent money".
So, you want your Rolex to be properly serviced by factory technicians at the actual factory, and turned around within one week including the shipping? KACHING!
I can dig it. I am old enough to remember.

Quote:
As minaret said, and cheechako's mention of NASA and clean rooms...if you have ever used a simple paint gun or airbrush, environmental factors can be a b|tch even with "simple" ink and paint. If you're trying to blend two chemicals accurately, with a physical gun that almost inevitably will now have flow problems on both liquids, and then you factor in environment and the costs of a climate-controlled boatbuilding shed large enough to accomodate multiple hulls, and still bring in some air for the dwarves to breath....
Stop by your local auto body shop and ask them how much fun it is trying to match a real high-flake metallic paint as the environment changes. And that's bearing in mind that now, unlike the 80's, the EPA requires those guys to use closed spray booths.
My cousin owned an auto body shop in AZ for years. A friend had a furniture refinishing business in California and the EPA shut him down, even after he paid thousands for the spray booth. My cousin never had a problem. I've sprayed everything from milk paint to aniline dyes to IMRON to 100% solids fillers for fabric covered aircraft. Spraying epoxy gives me the fits, I can never seem to get the flow correctly.

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I think it took 20 years, with mechanics pulling and retorquing the tires on my car to do the annual inspection, before I found ONE shop that properly retorqued them. And that operation involves simply turning a wrench. So, mixing, spraying, cleaning the sizing off the cloth or testing the cloith to make sure it has the right sizing on it? Way more opportunities to screw up, and once it has left the factory, who's gonna know if you screwed up, until 20 years later, when it isn't "your" problem any more?
That right there is a great example of why personally owning the service manual is a good thing.

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And I'd bet that as resin and material prices went up, suppliers were cheating too. That's also sadly normal in every business.
I object, hearsay and speculative.
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