Coating Thickness and Number of Coats

Why would you ask such a silly question?

"The specifications call for 3 coats , 3 MDFTPC "

Unless you get authorization to deviate from the spec, you will have a noncompliant coating of adequate thickness.

Why not one coat, 9 mil DFT?

Oh, wait... I can think of a reason. How about you; what would be a reason to not apply this much coating at one time?

Doorman...

I toally agree........ one coat......... 9 mil DFT !!!

Think of the manhours that will be saved !!!

Manhours saved! In the bank! Good deal. Do not be stingy with the GA button!

Let us say that you, dear Guest, ordered a hamburger sandwich with TWO standard squirts of catsup, and that order is accepted for assembly, the price agreed upon and paid. Upon taking delivery of your sandwich, you discover ONE BIG squirt of catsup in lieu of the two standard squirts you had specified.

Disregard any thought of material saved, labor saved, plant tool fade reduction, suitability equivalence, or process improvement. You did not get what you ordered, now did you? Does your money have less value than the next guy, you should not get what you wanted? Of course not.

Why oh why would you initiate a change such as this?

If you were to contact the manufacturer, like you should have done, they will probably tell you that two coats will work fine.

What the manufacturer is not going to do, is back you up when you get your a$$ handed to you for deviating from the spec's, which I assume you had when you bid the job. Give them what they're paying for and quit trying to cheat.

To answer your question, you run a definite risk of trapping solvents in your paint film by trying to apply 2 fat coats as opposed to 3. This can result in pitting and bubbling in final coat. Then you could find out how fun it is to strip polyamide epoxy.

Most of these can be recoated within a few hours, after sufficient gassing off time between coats.........just do it right the first time.

From the contractual standpoint, you need to know the environment in which the paint is to be working and the length of time before first maintenance. This is probably (although without full knowledge of the project in hand it is difficult to give absolutes) what has given rise the paint spec in the first place.

Then you can ask your paint supplier if two coats can be applied and how this can be done so as to meet the requirements of environment and durability.

Then you can propose your solution to the client and negociate if it is really suitable.

You will probably be saving money and the client will only want your solution if it presents a gain for him either monetary or technically better.

If you both agree to this change in contract and maintain the durability of the paintwork which is guaranteed by you and your paint supplier (who may want to supervise a little of your painting processes to ensure that all is in order) then all is okay.

But is it worth it ?

So, let me get this staight.

1) Get paint supplier to back him up with a guarantee, saying two thick coats will be as good as three. And put this in writing, of course.

2) Have client rewrite the spec's, because he decided he found a better/faster way.

3) I don't think it's worth it. And if it were to happen, hell would be frozen solid.

I like you kramarat, would caution anyone from doing anything without the supplier taking full responsibility for the change. Getting someone from their engineering department to bite on this is really not going to happen or extremely doubtful.

From my experience with these types of coatings, you better hold close to millage for coats required to build up to finial finish. I won't beat up the ins or outs as to why (already stated here), but solvents can be tricky to deal with depending on percent of solids in the materials used. If I were biding on a job such as this, discussion as to how and why would have been completed before signing onto do the job. Once signed onto it takes allot to uncover ones liability.

I've used a lot of polyamide epoxy in my life, and done experiments to see what I could get away with and what happens "if".

Preventing this kind of creativity is exactly why the spec was written the way it was.

Me too. As you say, the specification is written as it is because it needs to be that way.

Do it right.

Yep.

There is a way that he could do it, probably. But the sweet spot involves temperature, humidity and near perfect timing between coats. 10% chance of success, 90% chance of failure.

Manhours to put on one extra coat vs. manhours/materials to redo project makes it a no brainer. Which probably doesn't even matter, because the guest is probably long gone.