Pull Off Adhesion test 2

[corberg]

Dear Friends
When I conducted the pulloff ahesion test astm d4541 on plate with inorganic zinc as primer ,followed by one tie coat,the one hb coating 125microns and final a polyurethane, i got value is mpa with 100% cohessive failur from primer@ adft 325 microns . I want to know whether it is acceptable or not. If not pls let me the reason and the value.

 

[TomDOT]

Did you read ASTM D 4541? Are you familiar with it?

If so, you should be aware that results vary dramatically depending on which instrument is used.

So, which instrument did you use?

You also don't seem to give a value for the pulloff, just "mpa"

Cohesive failure within the primer is very common for zinc primers, whether IOZ or OZ.

What does the manufacturer's data sheet say for an expected pulloff test? How about your specification or contract?

 

[corberg]

Dear Tom
Thanks for your reply. I has read the ASTMD 4541,as per the paint manufacture the minimum value for pull of is 1.5mpa. But the clinet has a fear that it willnot pass the requirment. so confirming I had post the my dought

 

[babouic]

Corberg.
I don't really understand what you are expecting from this forum.
It seems that you had perform the pull-off test ( failure at primer), but you don't give us any value.
Which type of instrument did you use ? Mechanic ? Pneumatic ?

If you had perform the pull-off, you must have value from your instrument. It seems that you are expecting us to give you a value based on DFT, paint material and failure which is absolutely not possible. The pull-off value come from your instrument during testing.

Just perform the test with appropriate equipment and procedure and you will have your value.

 

[TomDOT]

1.5 MPa is a very low number, even for a Type II tester (which gives the lowest results) - commonly I would see at least 2.5 MPa requirement for a decently cured IOZ primer.

If your client is scared it won't pass - that's some poor quality (or improperly applied/cured) IOZ.

 

[corberg]

babouic
I used hydraulic pull off testing machine. I got a vlaue of 3.5 mpa for 2 dolly and one dolly I got 4.5mpa is it ok

 

[TomDOT]

corberg,

You got a mean result of 3.8 MPa. Your stated minimum was 1.5 MPa. Since the measured value is higher than the required minimum, it passed.

Separately, 3.8 MPa is a reasonable number for a hydraulic pull-off test of an IOZ primer.

Where is the problem?