Jotamastic 87 AL

[Lamby]

Would Jotamastic 87 AL be a good alternative to Zinga for a steel boat hull prior blacking ?

[Bargebuilder]

I would look very seriously at Chemco RS 500P before you make your decision.

https://www.chemcoint.com/products/epo-chem-rs-500p/

[rusty69]

I was under the impression zinga contains zinc. As far as I know Jotamastic 87 (and 90)is a two pack epoxy, which contains no zinc, so I would say it's not an alternative  comparable to zinga. 

 

If you want to apply Jotamastic, it is usually recommended that any old coating is removed by grit blasting prior to application. 

 

 

Edited July 25, 2023 by rusty69

[Lamby]

Thank you for your replies, I think i am going to leave the undercoat and just rely on 2 pack blacking, on account that using Zinga or jotamastic with the wrong top blacking could cause more problems then it solves if it works. 

[ditchcrawler]

8 minutes ago, Lamby said:

Thank you for your replies, I think i am going to leave the undercoat and just rely on 2 pack blacking, on account that using Zinga or jotamastic with the wrong top blacking could cause more problems then it solves if it works. 

I would have a word with Debdale Wharf who I thing do Zinger and 2 pk

[Lamby]

Will do cheers 

[dmr]

11 hours ago, ditchcrawler said:

I would have a word with Debdale Wharf who I thing do Zinger and 2 pk

They do a hot zinc spray which I suspect is much better than Zinga which is essentially a paint.

[blackrose]

If you do end up going for Jotamastic use it direct to steel (no undercoat or primer) and go for Jotamastic 90 rather than 87 as it's an updated version with better surface tolerance. Also unless you're on long-term hard standing order winter grade hardener even if you're going to be using it in summer because standard grade hardener takes a long time to fully cure and ideally you want it fully cured before the boat goes back into the water.

 

The aluminuim flake versions of Jotamastic 90 comes in silver and red toned shades which helps to differentiate the first and second coats when you're applying it. Once you come to 3rd & 4th coats in black it's quite difficult to see where you've already painted the 4th coat.

 

Finally don't attempt to use Jotamastic without downloading, printing out, reading and understanding the technical data sheets.

Edited July 31, 2023 by blackrose

[rusty69]

7 minutes ago, blackrose said:

Once you come to 3rd & 4th coats in black it's quite difficult to see where you've already painted the 4th coat.

Unless you buy red tint and add it to the black and get brown, as we recently discovered. 😂

[Lamby]

Thank you so much for your assistance, after lots of consideration I have decided to forget the Zinga and jotamastic instead I am using sml 2 pack keep it simple and if it lasts 10 years that’s good enough 

[blackrose]

What's SML two pack? Who's it actually made by (SML is a paint supplier rather than manufacturer) and why is using it any simpler than Jotamastic 90 two pack?

Edited August 9, 2023 by blackrose

[LadyG]

If you use Jotamastic 90, which is a two pack, ( I got the full kit from SML, plus advice, plenty of the right type of rollers etc). You should have everything you need onsite and best wait for a weather window if outside, it took me eight days. I did not know that it would weather, muddy grey,  over time, now I know, I would apply a topcoat of the Hardtop AX, but that might extend the time out of the water.

I did not do the baseplate, as the forum folks thought it would not pit and corrode due to lack of oxygen, now they think it should be protected, that's a significant amount of extra work.

[matty40s]

I did not do the baseplate, as the forum folks thought it would not pit and corrode due to lack of oxygen, now they think it should be protected,

 

ah, methinks you have been either not reading correctly, or just made your mind up from a historical perspective.

Forum members have not said it would not pit and corrode due to lack of oxygen at all. 

The reason baseplates are thicker, first 6, then 10, or 12, or even 15 for a few, is that it lasts longer, and takes longer to degrade to an uninsurable thickness. There are also far fewer docking facilities where you can actually get at the baseplate for work, and it is far more likely to scrape off anyway.....hence the increases in thickness in hull manufacture.

The only other reason for thick baseplate is that you dont need ballast, as much, or at all, thus allowing greater headroom or a lower roofed boat.