[Lightningboy65]

So, how does this relate to the thread? I'm not getting the inside joke.

Because in order to put on two coats, one needs a good breakfast.:glasses:

 

[Lightningboy65]

In a lot of cases (and I mean in many businesses- not just painting) you get your whole family involved and they are working cheap- if not just for room and board. Hard to compete with that when you and your help have so many real world bills to pay.

Main reason the Amish can underbid just about anybody. Not because of the old "they don't pay taxes" line. And many people believe that. They pay the same taxes as others, with the exception of FICA taxes. They don't participate in Medicare or Social Security, so they don't pay FICA. But at least they are paying all other taxes, unlike most illegals doing contract work.

 

[Lightningboy65]

Is there test data comparing longevity of exterior wood two 3 mil coats dried between compared to a board with a single 6 mil wet coat? I've asked this a few times, and never got an answer...

Your question piqued my interest, and I spent a while searching online and could find nothing of the sorts. I couldn't even find anything on just plain old one coat vs. two. There must be something on the subject buried deep in the innerwebs, but I couldn't find it.:sad:

Common sense and experience leaves me no doubt a two coat job will significantly outlast a one coat job, but I have no empirical data to back that up. I know two coats will always look better.

 

[Lightningboy65]

This ties right in with beating out the illegals. Your selling a lexus with 2 shiny coats of finish, they have the used corrola with 1 coat of cheap paint on it.

The problem is the illegals who give 2 shiny coats of finish plus a hand rubbed 3 coat wax job, and are still at half the price as above board companies! Not all illegals do crappy work, I've seen some pretty good work by guys I'm pretty sure had no legal standing in this country. But the fact they are not paying taxes and insurance makes it hard to compete with them. It won't stop until those hiring them refuse to do so...which will be never.:sad:

 

[Lightningboy65]

But what is dried paint? It's the resin, pigment, binders, and additives left behind after the vehicle solvent has evaporated. Essentially, a solid Acrylic film.

Upon reviewing post # 82, this post,and getting things straight in my head, all I can say is...I agree.

I was confusing thermoplastic and thermoset plastic.:surprise:

 

[Lightningboy65]

But because PMMA is a major component of a WB Acrylic paint resin, it places that coating in the thermoplastic category verses the thermoset plastic category. That's just scientific fact. I learned this from the SSPC C1 Coatings course I took some time back. It isn't really all that relevant to know this information, but it offers good material for internet debates. lol!

I can dig that, bro. It might put them in that category, but they really don't adhere to the curative properties of such. The PMMA is in suspension, not solution. The PMMA in the paint is already cured. Only the paint itself needs to cure, not the PMMA.

 

[Lightningboy65]

Coatings designed to be applied at a single WFT of 20, 40, and higher mils already exist. It's all about the SBV%.

I was referring to regular old house paints, which if you had a bunch of guys "puttin' it thick" would definitely result in a higher incident of runs, droops,and drips

But yeah, some coatings are designed to go on thick without adverse consequences.

 

[Lightningboy65]

So much passion expended on something probably 98% of us never even think about - actual mil thickness.

Guess I’m just a hack for admitting I never once used, let alone owned, a device to measure the thickness of coatings. But then I never did jobs requiring specific thicknesses. I just pretty much always did (and do) two coats in the belief that it looked and held up better. Tests saying one thing over another likely never would have made a difference to me and certainly wouldn’t have resulted in major changes in my process.

But imagine all the time saved if indeed it were revealed through scientific testing that a single 6 mil coat was as good or better than two 3 mil coats!

Also imagine all of the additional runs and drips!:biggrin:

Unfortunately ,I had to deal with mil specs more than I would have liked!:sad:

 

[Lightningboy65]

You still have a chance to get on board.

Resourced from Wikipedia:
Poly(methyl methacrylate) (PMMA), also known as acrylic, acrylic glass, or plexiglass as well as by the trade names Crylux, Plexiglas, Acrylite, Lucite, and Perspex among several others (see below), is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass. The same material can be used as a casting resin, in inks and coatings, and has many other uses.

Is that on the same innerwebs that Al Gore invented?:biggrin:

In its pure form, PMMA is indeed a thermoplastic. Using it as a component of latex paint does not make that paint subject to the to curative properties of thermoplastic materials.

 

[Lightningboy65]

Single component coatings, including those with latex and acrylic resins, are considered thermoplastic materials because they can be returned to their original state, or something like that.

We will just have to agree to disagree on this point.:wink:

 

[Lightningboy65]

It's true, and often lamented by painters, that controlled environment testing doesn't represent real world conditions. But I suppose there needs to be a level of trust involved in laboratory testing. For example, airstream testing over the wings of a Boing 757 hopefully provide a pretty good idea of what will occur at 30,000 ft.

Agreed, but it would be nice to see the actual test outcomes.:sad:

 

[Lightningboy65]

But to your second point, and generally speaking, the science of thermoplastic film formation requires that the vehicle solvents fully evaporate during coalescing. What we read in the product TDS, in terms of WFT and DFT, and recoat times, are the results of Lab testing that provided the best performance outcomes from the coating. It also provides a guide line for recourse if there were a failure to occur.

Since traditional latex paints do not involve thermosetting mechanisms, and rely on evaporation to cure, this really wouldn't apply to traditional latex house paint.

Well ,the solvents would need to be fully evaporated, but thermoplastics has nothing to do with it.

 

[Lightningboy65]

But to your second point, and generally speaking, the science of thermoplastic film formation requires that the vehicle solvents fully evaporate during coalescing. What we read in the product TDS, in terms of WFT and DFT, and recoat times, are the results of Lab testing that provided the best performance outcomes from the coating.

I have a feeling this is generally true, and for this reason have
always personally held to the personal practice of two thinner coats.

As to this lab testing you speak of ...where are these studies and the resulting data??? I have found it virtually impossible to track down the actual lab tests, and more importantly the empirical data???

 

[Lightningboy65]

Single component paint films cure by coalescence (evaporation of solvents) rather than by chemical crosslinking that typically occurs with two component coatings.

For single component waterborne coatings, adhesion of subsequent coats of paint rely on penetration into the micro-perforated film matrix of the first, provided that most if not all of the first coat solvents have evaporated.

Many of the newer latex coatings employ crosslink technology - at least that's what the labels claim. Duration and Valspar Hi-Def are two that come to mind.

And who's to say the bond of the second coat to the micro-perforated film matrix of the first is better than having only one thicker coat where that bond interface is non existent? If testing has been done, the results are not readily available.

 

[Lightningboy65]

This makes total sense to me.

And to understand correctly, Woodco is asking what affect the same time line and exposure has on two different boards that were painted with an identical coating system with identical total Dry Film Thickness. But, with the exception that one board had a single Wet Film Thickness application compared to the other board that had two separate WFT applications with appropriate dry times in between.

What makes the difference in the two applications is that the single WFT may have had it's full film formation compromised due to solvent entrapment compared to the two coat WFT application recommended by the manufacturer's TDS.

For example, trying to push a coating's recommended WFT, can result in a "cake" phenomena where the shell cures to a relatively hard surface, but leaves the middle a little soft. Obviously, the designed performance of a coating in this condition has been compromised. Unfortunately, this is all at a molecular level that is hardly recognized by a painter who simply rubs their paw over a dried painted surface.

Or it could be that the cross linking properties between the two coats ,in the total film thickness, are compromised by applying the film in two coats. Any supposition without a controlled scientific test is merely just that, supposition. And it appears for reasons unknown, these test results, should they exist, are a closely guarded secret. Perhaps we should employ the Russians to dig them up.

For the record, I feel two thinner coats are better. Unfortunately I have no empirical data to back up my hypothesis.:glasses:

 

[Lightningboy65]

Your post said two coats of 3mil dry, but semantics aside, PAC gave a better reason for two coats. I don't think you can go off of your common statement, as who can say what a light coat is vs a heavy coat? Really a coat of paint is a coat of paint regardless how thick the product is or how you apply it.

I realize many on PaintTalk may not deal with projects that involve mil spec inspections, those that do realize a coat of paint is not a coat of paint. If working a mil spec job, you had better be certain you are putting it on thick enough.

And not only to pass inspection. Some coatings, elastomerics for example, will not perform as they should if millage is not high enough. And I feel a thicker coat, in most cases, is superior to a thinner coat. No data to back that one up, just my gut feeling.

Dip it to the chrome, and put it on like you're not payin' for it. Because you're not payin for it. If you did your estimating right, the customer is!

 

[Lightningboy65]

However, it did provide a lot of laughs when everyone was half in the bag and us guys took turns chasing the girls around with the head!

Better be careful, in some cultures you're considered married after pursuing a female with a pig's head!:surprise:

 

[Lightningboy65]

Guanciale is Italian bacon made from the cheek and jowl . And it is , of course, delicious.

 

[Lightningboy65]

Once you've had it, you know!

If you're ever at a pig roast, that is the first thing to go for. Those in the know, know.:vs_OMG:

 

[Lightningboy65]

a piece of cheek meat! Boy that was some damn good eatin'! Best meat on the planet! Screw that Japanese beef crap!

Truer words have never graced these pages!!! Amen.