Zinc rich primer Vs Zinc Rich epoxy 3

[Metallurgistrbi]

I came across a client specification which reads like this
1. Zn rich primers shall be 2 pack epoxy media and must contain 80% metallic zinc by weight in dry film
2. Zn rich epoxy shall have 40% min. weight content of epoxy.


How can both be possible at the same time?

or Am i missing something.?

Thanks in advance for your inputs and feedback.

 

[SJones]

Is it use of the term 'dry film" that is the key difference versus the original liquid formulation?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[dik]

Yes Steve...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[3DDave]

Epoxy doesn't cure by evaporation of solvent so whatever the zinc content it will remain the same from wet to dry.

It sounds like the primer is 80% and the top coat is 40%, but that answer really needs to come from the client. At 40% there is considerable option for color, at 80%, not so much.

 

[TugboatEng]

Not all epoxy coatings are 100% solids. There is shrinkage between wet film and dry film thickness.

 

[Metallurgistrbi]

Thanks all for the feedback.

@3DDave., The midcoat given as follows.
MIO pigmented with 50% laminar MIO by weight in dry film.

So I guess, the first 2 points are talking about primer., hence it doesnt make sense to me.

I have attached the snip for reference, if that would be of any help

 

[3DDave]

Note a is about primer.

Note b is about paint.

Is that attached image from the client?

These appear to be notes for some other drawing that confirms which combination is required.

 

[SJones]

Take a look at a manufacturer's datasheet for a zinc rich epoxy primer. Let's take Hempel Hempadur Zinc 17360 for example (no promoting here, just an illustrative example):

1. It states "In compliance with SSPC-Paint 20, type 2, level 2" - thus it claims to be an organic zinc rich coating containing a zinc dust pigment at 75% < x < 85% (BY WEIGHT)

2. It has a volume solids of 65 +/- 2% ( = Dry Film Thickness/Wet Film Thickness)

3. It also has a nominal VOC content - meaning that there will be some evaporative losses

4. It does not give an epoxy content

You just have to think how does a nominal 80% zinc content still only register a volume solids of 65% (WEIGHT v VOLUME)

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Metallurgistrbi]

thank u all for your valuable feedback

@Sjones. Thanks for the insight. Didnt thought that way.

@3Ddave

Yes it was a snip from client specification.

 

[Metallurgistrbi]

@Sjones.

I came across 17360. In their safety data sheet epoxy content given as max. 10% where as % Zinc (Zinc + zn oxide) comes around 80%. so the first point is satisfied where as the 2nd point is not.

I am still at loss about how to interpret this.?

 

[3DDave]

Where does the 2nd point come from? I don't see anything that says both points are for the same material. I do see where the two requirements are for two materials.

 

[SJones]

@3DDave: in point 2, what else is a Zn rich epoxy going to be used for, apart from a primer or as a repair for galvanising?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[3DDave]

Great question SJones - ASK THE ORIGINAL POSTER LIKE I DID.

HERE"S WHAT HE IS WORKING FROM:

 

[SJones]

Indeed, as the OP is finding out, the inclusion of “i.e. zinc rich epoxy” is not compatible with the associated requirement of 40% weight content of epoxy.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[dik]

That was my concern with my initial comment that I deleted.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[WKTaylor]

Zinc-rich epoxy primers come in a lot of flavors... What Specification(s)???

Aerospace?
Civil Engineering?
Maritime/ship/structures/etc?

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[dik]

I wasn't aware of the coating that Steve mentioned... but looked into it, and have added it to my list of coatings.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik