Two coats of Micron 350 in one day advisable?

MagicalArmchair

MagicalArmchair

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Tomorrow I will finish sanding the underside of Mirage and then put on the first coat of Micron 350. I aim to have prep finished by 10am, and I'll start painting then.

I'll plan to have that first coat finished by Midday. The average temperature tomorrow is circa 10 degrees.

I know at 3pm, I'll be tempted to wack on the second coat, as to my untrained eye, it'll look dry, to get it done, however, that only gives 5 hours drying time. The "book" here: https://www.international-yachtpain...96.1719773082.1647420578-276765360.1647420578 suggests at 10 degrees I'll need around 13 hours of drying time.

So, I guess I should stifle my enthusiasm to get back on the water and wait 'till Saturday to put on the second coat?
 
I've undercut overcoating times in the past, with no ill effects. Even so, I think you'll be cutting it fine to do it in one day at this time of year. I'd leave it for another day.
 
I always put two coats on parts of the hull within a few hours. I use either best Micron or Seajet 033, one thinned rolled coat all over, then by the time that has dried go round the waterline top 6" to 9" and the leading edge of keel and rudder with a second thinned coat. Done this many times, never a problem. Aiming to do this year's worth tomorrow. Normally this works well for 8-9 month season afloat. 2.5 litres a year for a 35 ft boat in a quite high fouling area - the unantifouled mooring buoy and chain/warp gets a lot of weed and mussels in the same period.

I believe a lot of antifoul is profitably sold by recommending two unthinned coats all over, and this approach guarantees a thick crusty build-up over the years. For the same reason I don't use cheap antifoul, better thin coat(s) of good stuff than lots of cheap stuff. After 15 years with a light wet mesh abrasive rub down each winter the boat has still not had to have old AF stripped off: the hull condition would not be good enough for semi-serious racing but is fine for cruising for someone who still appreciates sailing fairly quickly.
 
jwilson said:
I always put two coats on parts of the hull within a few hours. I use either best Micron or Seajet 033, one thinned rolled coat all over, then by the time that has dried go round the waterline top 6" to 9" and the leading edge of keel and rudder with a second thinned coat. Done this many times, never a problem. Aiming to do this year's worth tomorrow. Normally this works well for 8-9 month season afloat. 2.5 litres a year for a 35 ft boat in a quite high fouling area - the unantifouled mooring buoy and chain/warp gets a lot of weed and mussels in the same period.

I believe a lot of antifoul is profitably sold by recommending two unthinned coats all over, and this approach guarantees a thick crusty build-up over the years. For the same reason I don't use cheap antifoul, better thin coat(s) of good stuff than lots of cheap stuff. After 15 years with a light wet mesh abrasive rub down each winter the boat has still not had to have old AF stripped off: the hull condition would not be good enough for semi-serious racing but is fine for cruising for someone who still appreciates sailing fairly quickly.
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What do you thin it with, and by how much? Just about to top up antifouling with Micron 350 where the hull finish is good and I would rather avoid the traditional moonscape in the future. I’ve always had Coppercoat before so I know very little about proper antifoul. ?
 
The thinners they sell for the AF.
mrming said:
What do you thin it with, and by how much? Just about to top up antifouling with Micron 350 where the hull finish is good and I would rather avoid the traditional moonscape in the future. I’ve always had Coppercoat before so I know very little about proper antifoul. ?
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The thinners they sell for whichever AF I am using. And stir it well (but slowly) with a drill-mounted stirrer
 
MagicalArmchair said:
Tomorrow I will finish sanding the underside of Mirage and then put on the first coat of Micron 350. I aim to have prep finished by 10am, and I'll start painting then.

I'll plan to have that first coat finished by Midday. The average temperature tomorrow is circa 10 degrees.

I know at 3pm, I'll be tempted to wack on the second coat, as to my untrained eye, it'll look dry, to get it done, however, that only gives 5 hours drying time. The "book" here: https://www.international-yachtpain...96.1719773082.1647420578-276765360.1647420578 suggests at 10 degrees I'll need around 13 hours of drying time.

So, I guess I should stifle my enthusiasm to get back on the water and wait 'till Saturday to put on the second coat?
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You will be exhausted when you finish sanding, assuming you are doing to properly. And properly would mean it will take longer than putting on one coat of AF.

The temperature you quote ins a forecast - would you bet money on it....?

Micron is not cheap - don't risk it.

AF works based on two conditions

You use your yacht

You apply the AF generously.

If you want, approx, 2 year life, don't thin it, apply 2 coats.

If you are happy to slip annually after 6 years you will have the same thickness of old AF as if you painted every 2 years. But the costs of slipping will double.

Take care, stay safe

Jonathan
 
Neeves said:
You will be exhausted when you finish sanding, assuming you are doing to properly. And properly would mean it will take longer than putting on one coat of AF.
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It took me a week of solid work on Jazzcat - 8m catamaran - more when you count the days when it rained or life got in the way

The boot top took two days - masking and one coat, second coat the next day. Then, with Milady helping, it took us a good day to put 1 1/2 coats - two full tins - of antifoul on. The next few days are looking warm and sunny, so I'd expect two coats to go on a monohull in a day. I reckon you could pretty much start at the bow, go down one side and back up the other. Don't stop until you run out! If you do leave it overnight, you'll have to wait for any dew to dry completely, which takes a while, especially on the shady side.

Still, the number of people I see on our scrubbing grids scrubbing off, masking and painting between the tide going out far enough and coming back in... OTOH, that might have something to do with the grumbles about AF being rubbish! My AF said minimum 8 hours, max 2 months between application and launch.
 
Noting Stemar's post - the OP made no mention of scrubbing off :( - if you need to clean before sanding its best done with a high pressure hose - but if you do 'by hand' - it depends how bad it is but think 2-4 hours. Cleaning the prop, saildrive, removing and replacing anodes takes time and is not in a user friendly position - but if you have the stamina.....

I take our props off, give them to Josephine and she cleans them, Demell or equivalent, and then applies AF. She also does the taping and catering. I'm simply 'labour' and apply the AF and replace the props. We assume a 2 days event and live on our cat for the duration - so no travel time.

We also, generally, have reliable weather :)

We also don't mind the exercise - its not a chore.

Jonathan
 
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