Applying two pack blacking

[Arthur Marshall]

Any handy hints welcome, I've got to do a general touchup on the boat and haven't used this before;  always used bitumen, but the yard used two pack last time instead.

[Tracy D'arth]

Do not mix too much at a time, in warmish weather it will start to thicken up in about half an hour. Use disposable paper cups to measure out part of the resin and reactor.

 

Pound shops sell cheap fence treatment brushes, nothing you use will be any good afterwards. Rollers do work but you have to be gentle with foam ones, fluffy ones leave bits in the paint.

The solvent is pure acetone but only before it sets. Your clothes will be scrap, a pair of disposable paper coveralls are better.

Plastic gloves are better than latex ones.

 

Cut down plastic milk jugs are handy for mixing in, use only once and discard.  Scruff up the existing coating a bit after washing off and remove the dust.

Grind rust spots down to bright steel.

[Arthur Marshall]

That's really helpful, thanks.

[blackrose]

1 hour ago, Arthur Marshall said:

Any handy hints welcome, I've got to do a general touchup on the boat and haven't used this before;  always used bitumen, but the yard used two pack last time instead.

 

More info required. Which two pack did the yard use last time, how long ago was that and are you using the same paint?

[blackrose]

1 hour ago, Tracy D'arth said:

Do not mix too much at a time, in warmish weather it will start to thicken up in about half an hour. Use disposable paper cups to measure out part of the resin and reactor.

 

The solvent is pure acetone but only before it sets. 

 

Grind rust spots down to bright steel.

 

Some of what you've said I agree with but not necessarily these bits. To many generalisations.

 

Pot life really depends what epoxy you're using and which grade of hardener. I used Jotamastic 87 for example and with standard grade hardener pot life was a couple of hours even in warm weather. I managed to mix and apply a full 4 litre can by myself in that time.

 

I'm not aware of which epoxy paints use acetone as solvent, but the stuff I use is based on a xylene solvent.

 

Don't grind rust spots because you'll grind away good steel. Use a wire wheel on an angle grinder.

[dmr]

1 hour ago, blackrose said:

 

Some of what you've said I agree with but not necessarily these bits. To many generalisations.

 

Pot life really depends what epoxy you're using and which grade of hardener. I used Jotamastic 87 for example and with standard grade hardener pot life was a couple of hours even in warm weather. I managed to mix and apply a full 4 litre can by myself in that time.

 

I'm not aware of which epoxy paints use acetone as solvent, but the stuff I use is based on a xylene solvent.

 

Don't grind rust spots because you'll grind away good steel. Use a wire wheel on an angle grinder.

 

Epoxies use just a very small amount of solvent to help them flow, otherwise it would be like painting with araldite. Dr Bob told us this ?

 

Acetone can be used for cleaning brushes, but no good once the epoxy has set. I don't know if acetone is universal but I know it works with Jotamastic 87 and the West System 'cus Ive done it.

 

..............Dave

 

 

[LadyG]

Read the data sheet, and make sure the weather forecast fits with the epoxy eg Jotun jotamastic 90 has three grades, and very different data sheets

Edited May 13, 2021 by LadyG

[Chagall]

8 minutes ago, LadyG said:

Read the data sheet, and make sure the weather forecast fits with the epoxy eg Jotun jotamastic 90 has three grades, and very different data sheets

Might be nice if you credited Thunderboat for that advice that you found there? 

[Bee]

Don't get it in your hair. Don't get it on your glasses, you will have spots before your eyes forever. Don't get it on your dog. Don't get it on your underpants (or anywhere down there) I have a pair of underpants with an orange thumbprint on them still just about discernible from the docking before last. OK I know, nobody wanted to know that.

[Idle Days]

27 minutes ago, Bee said:

Don't get it in your hair. Don't get it on your glasses, you will have spots before your eyes forever. Don't get it on your dog. Don't get it on your underpants (or anywhere down there) I have a pair of underpants with an orange thumbprint on them still just about discernible from the docking before last. OK I know, nobody wanted to know that.

 

It all adds to the knowledge base. 

[Col_T]

11 hours ago, Chagall said:

Might be nice if you credited Thunderboat for that advice that you found there? 

 

Not sure I really get that - the important thing is that the advice is being shared, surely?

[Arthur Marshall]

Can't see it matters where advice comes from, just glad to have it. No reason to credit a forum, a book, the notes on the tin or personal experience.

I have no idea what the yard used, it was two years ago. I've got a tin of Jotamastic 87, and a couple of big tins that say Jotun on them, one round and one rectangular. I got the lot from someone on here a few years back and haven't used it yet...

[dmr]

4 minutes ago, Arthur Marshall said:

Can't see it matters where advice comes from, just glad to have it. No reason to credit a forum, a book, the notes on the tin or personal experience.

I have no idea what the yard used, it was two years ago. I've got a tin of Jotamastic 87, and a couple of big tins that say Jotun on them, one round and one rectangular. I got the lot from someone on here a few years back and haven't used it yet...

The '87 is good but don't use the other stuff till youv'e worked out what it is ?

 

If the Jotun 87 is very old it might have gone a bit stodgy but should still be ok. You might need to warm it a little to get it to flow nicely. Even if its not very old the black component will likely have formed into a sticky lump. You will need to stir it really well before you can use it. This is hard work and takes ages so do it well in advance and then a quick stir just before you use it.

 

The old stuff on the boat might well have faded/gone grey over time. The new stuff will be black so if you don't want a spotty boat put one coat on the scrapes then a second coat over the entire boat. The yard that does our epoxy don't even bother with patching, they just put two full coats over the entire boat, putting extra coats on every few years does not appear to cause any problems.

 

...............Dave

[blackrose]

30 minutes ago, Arthur Marshall said:

Can't see it matters where advice comes from, just glad to have it. No reason to credit a forum, a book, the notes on the tin or personal experience.

I have no idea what the yard used, it was two years ago. I've got a tin of Jotamastic 87, and a couple of big tins that say Jotun on them, one round and one rectangular. I got the lot from someone on here a few years back and haven't used it yet...

 

I've got a fair amount of experience using Jotamastic 87. The first thing to do is download the data sheets for the product and have a read.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.jotun.com/Datasheets/Download%3Furl%3D%2FAG%2FAG__515__Jotamastic%2B87__Euk__GB.pdf&ved=2ahUKEwiPmvLlmsnwAhWSCGMBHSpQCWAQFjAAegQIChAC&usg=AOvVaw2CwfhptsokCn1eCQYDBNLp&cshid=1620996575862

 

Pay particular attention to the mixing instructions and minimum/maximum overcoating times which may be dependent on the grade of hardener you're using.

 

Which grade of hardener do you have for the Jotamastic 87, standard or winter grade? That's the smaller tin that comes with the paint. I'd recommend the winter grade hardener simply because it means you can get your boat back in the water without having to wait for days for the paint to fully cure. Some say it will continue curing while in the water but I only know what jotun uk lead technical person told me on the phone. I have no personal opinion on it.

 

You'll also need a some jotun 17 thinners. Unfortunately I think it's only available in 5 litre containers.

 

If you don't know what the other two tins of paint are then don't use them and get rid of them. Using them is a false economy just because they were free.

 

If you need advice send me a PM.

8 minutes ago, dmr said:

You will need to stir it really well before you can use it. This is hard work and takes ages so do it well in advance and then a quick stir just before you use it.

 

 

Yes and stir the large tin will before adding any hardener - or decanting it to a separate container

Edited May 14, 2021 by blackrose

[Arthur Marshall]

2 hours ago, blackrose said:

 

I've got a fair amount of experience using Jotamastic 87. The first thing to do is download the data sheets for the product and have a read.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.jotun.com/Datasheets/Download%3Furl%3D%2FAG%2FAG__515__Jotamastic%2B87__Euk__GB.pdf&ved=2ahUKEwiPmvLlmsnwAhWSCGMBHSpQCWAQFjAAegQIChAC&usg=AOvVaw2CwfhptsokCn1eCQYDBNLp&cshid=1620996575862

 

Pay particular attention to the mixing instructions and minimum/maximum overcoating times which may be dependent on the grade of hardener you're using.

 

Which grade of hardener do you have for the Jotamastic 87, standard or winter grade? That's the smaller tin that comes with the paint. I'd recommend the winter grade hardener simply because it means you can get your boat back in the water without having to wait for days for the paint to fully cure. Some say it will continue curing while in the water but I only know what jotun uk lead technical person told me on the phone. I have no personal opinion on it.

 

You'll also need a some jotun 17 thinners. Unfortunately I think it's only available in 5 litre containers.

 

If you don't know what the other two tins of paint are then don't use them and get rid of them. Using them is a false economy just because they were free.

 

If you need advice send me a PM.

 

Yes and stir the large tin will before adding any hardener - or decanting it to a separate container

PM sent...

[LadyG]

6 hours ago, Col_T said:

 

Not sure I really get that - the important thing is that the advice is being shared, surely?

I don't think that was the exact advice, as it happens I had contacted two paint firms, got similar recommendations, the Jotamastic 90 is good for imperfectly prepared surfaces, I looked at the websites and discovered it is important to decide which one to use, most people would assume that Jotamastic 90 is is one mix, but there are three mixes under one name.

90

90 Al

90 WG

People on this site often lose sight of the name 'discussion', and like to engage in unarmed combat. Thunderbolt is much more relaxed in that respect. 

Edited May 14, 2021 by LadyG

[Arthur Marshall]

Thanks to everyone who's advised. I'm pretty sure I now know what I'm doing, and if it turns out I don't I've only got myself to blame.

As to unarmed combat, it's lucky that forums aren't a contact sport...

[Alan de Enfield]

1 hour ago, LadyG said:

People on this site often lose sight of the name 'discussion', and like to engage in unarmed combat.

 

 

“Never have a battle of wits with an unarmed person,”, its just not fair.

 

Mark Twain 

 

An intellectually unarmed person is not that one who does not know an argument but that one who is not willing to know it because he suffers from a deep motivated ignorance. That is, he decides not to understand, not to know, not to deepen, not to listen …

Edited May 14, 2021 by Alan de Enfield