40 Grit Disc for Jotamastic 90?

[conor1n]

Evening all,

Just a quick question for you. As title really... but I'm at my wits end with this stuff ever since my job peelee after polishing some of surface with a non woven disc, resting in flaking.

So I'm just about to spray some plate for a friend. What I've done is prepared the surface with fresh 40 grit Disc on grinder. Then to clean surface its Upol slow drying degreaser.

How does this sound to you? The pictures so the surface fairly scored up albeit at a more microscopic level. Would that be sufficient to make it ST2 ISO surface prep grade ?


Thanks a lot guys

P.S. I know blasting is best and I have all that gear...but life is too short as I don't have a suitable environment.

 

[ajlelectronics]

Have a look at the Jotun TDS but 40 is far too coarse for Lechler. 120-180 is the specification for first primer coats, my guess is that Jotun may be similar.

 

[conor1n]

Have a look at the Jotun TDS but 40 is far too coarse for Lechler. 120-180 is the specification for first primer coats, my guess is that Jotun may be similar.

Interesting. The TDS doesn't say anything about grits. Just refers to ST2 ISO 8501, which I'm having a hard time figuring out.

Whats the downside to too coarse a grit? Shrink back on the finish? I can't imagine that would happen with the mastic as it's so thick? Especially because they say it fan be used unthinned with a putty knife to fill rust pitting.

 

[Dcal]

Coarser the better, more surface area and a nice grippy surface for the primer.

40 will be fine, problems will only occur on painted or softer material where it might create deep scratches which could show when the paint drys.
On bare steel it will not be an issue

 

[conor1n]

Coarser the better, more surface area and a nice grippy surface for the primer.

40 will be fine, problems will only occur on painted or softer material where it might create deep scratches which could show when the paint drys.
On bare steel it will not be an issue

Sweet. Sounds like I did something correct first time around eh!?

I was a little worried some places were more polished than scored, so I have a quick blast of the DA with an 80 grit Disc.. so hopefully I will get good adhesion.

Thank you so much for clarifying.