Hardness/durability of Jotamastic 87...?

[RaceDiagnostics]

Here is a thought, did you thoroughly stir the paint before mixing the hardner. Mine was thin at the top of the pot and very thick at the bottom, took a lot of stirring to get it consistent before I used it.

 

[steveo3002]

i mixed mine out by volume ....if its a small touch up then spoon it out

 

[Maxakarudy]

It would take a bit math/s (US) to work it out gravimetrically over volumetrically and with digital scales and get it accurate, maybe I'm gettin a bit anal now

 

[RaceDiagnostics]

Another thought, what colour is it, different 87 colours have different mixing ratios.

 

[vdubz]

Also important to let it sit for the induction time of 10 minutes after you've mixed it up.

 

[The Z'eer]

Here is a thought, did you thoroughly stir the paint before mixing the hardner. Mine was thin at the top of the pot and very thick at the bottom, took a lot of stirring to get it consistent before I used it.

I did. I remember when I opened the tin and discovered just how gloopy and thick it was at the bottom. I guess I stirred it for around five-ten minutes to disperse the paint. You're right it was thin at the top, mostly clear.

 

[The Z'eer]

Another thought, what colour is it, different 87 colours have different mixing ratios.

Gloss back, says 4:1 on the tin.

 

[The Z'eer]

It would take a bit math/s (US) to work it out gravimetrically over volumetrically and with digital scales and get it accurate, maybe I'm gettin a bit anal now

Yeah, digital scales are gonna be needed.

 

[ronan]

Gloss back, says 4:1 on the tin.

I bought a liter of 2-pack paint a few weeks ago and the guy in the shop said it is a 4:1 mix, is this the way its going now ?

 

[Maxakarudy]

I bought a liter of 2-pack paint a few weeks ago and the guy in the shop said it is a 4:1 mix, is this the way its going now ?

Is this a primer or a gloss?, usually gloss is 2:1, sometimes 3:1, never heard of 4:1

 

[steveo3002]

insist on manf data sheet , minimum wage shop workers dont always know best

 

[ronan]

Is this a primer or a gloss?, usually gloss is 2:1, sometimes 3:1, never heard of 4:1

Gloss, its on the label on the can too.

 

[richie00boy]

Some modern clears are 4:1 also seen 3:1 so I wouldn't worry about it.

 

[Charlie390]

I replaced the boot floor of a 4x4 and brush painted it with Jotamastic 87 winter mixture. I mixed it by weight using digital scales. Brush painted it on aswell and didn't pay too much attention to how thick it was. It is as hard as rock now, like someone else mentioned, I spilled some on a cement floor and had to resort to using a hammer and chisel to get it off. Gave up after 30 mins as it was too hard!

I reckon it must be down to your mixture. Here's a link to mixing by weight: https://www.smlmarinepaints.co.uk/files/library/files/2 pack weights 0314.pdf

 

[Dcal]

Thanks for the link Charlie. I also find it easier to mix paint by weight, especially really thick paints like Jotamastic 87 which is hard to judge in small quantities. Ive resorted to measuring out a liter of paint and hardener and then weighing it to work out the specific gravity. Your link saves a lot of hassle as I usually lose my working out.

 

[langy]

I bought a liter of 2-pack paint a few weeks ago and the guy in the shop said it is a 4:1 mix, is this the way its going now ?

You can get 5-1 sometimes, that's why you should always get a spec sheet

 

[henry Kadzielski]

good morning gents.
This may now be a bit late, but I use Jotun paints quite a bit and Jotamastic 87 alli. This is a 5.5:1 mix, and yes it is temperature sensitive. There is however an accelerator that can be used and is available. Please note that there is accelerators for all paints that are two pack (Jotun ) for sure. I always mix by volume and have cups that are graduated up to 5:1 and have not had any trouble. The manufacturer data sheets are there for a reason, use them. I normally air spray or airless apply the coatings, without problems, however some of the paints I have supplied when applied by the end users have not gone to plan. I did not see them mix it or apply it so cannot comment. When frustration has finally got the better of them and they have called me in and have watched me mix and apply the coating, they said it will not work. Low and behold the coating was fine cured in the time specified, coating didn't change colour and was fine.
Their explanation, I must be gifted or the paint fears me

 

[langy]

good morning gents.
This may now be a bit late, but I use Jotun paints quite a bit and Jotamastic 87 alli. This is a 5.5:1 mix, and yes it is temperature sensitive. There is however an accelerator that can be used and is available. Please note that there is accelerators for all paints that are two pack (Jotun ) for sure. I always mix by volume and have cups that are graduated up to 5:1 and have not had any trouble. The manufacturer data sheets are there for a reason, use them. I normally air spray or airless apply the coatings, without problems, however some of the paints I have supplied when applied by the end users have not gone to plan. I did not see them mix it or apply it so cannot comment. When frustration has finally got the better of them and they have called me in and have watched me mix and apply the coating, they said it will not work. Low and behold the coating was fine cured in the time specified, coating didn't change colour and was fine.
Their explanation, I must be gifted or the paint fears me

Nope you just followed the specs, things work fine when done correctly, amazes me how many people try to bend the rules and then moan when it goes wrong !!!

 

[MG David]

I think one of the spec sheet details often ignored is the dwell time. People are in a hurry to get started so the paint does not set in the pot.

 

[The Z'eer]

I replaced the boot floor of a 4x4 and brush painted it with Jotamastic 87 winter mixture. I mixed it by weight using digital scales. Brush painted it on aswell and didn't pay too much attention to how thick it was. It is as hard as rock now, like someone else mentioned, I spilled some on a cement floor and had to resort to using a hammer and chisel to get it off. Gave up after 30 mins as it was too hard!

I reckon it must be down to your mixture. Here's a link to mixing by weight: https://www.smlmarinepaints.co.uk/files/library/files/2 pack weights 0314.pdf

That's a very helpful link there, great info