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How soon after the first coat is it preferable before you to rub down?

How soon is it preferable to wait before second coat is applied?

 

On a bit of a timescale in dry dock.

Edited by Midnight
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OK, 

Big thing is to sand with power sanders using everything from 80/40 to 240  grit, with even finer if you are going for broke.

Loads of stuff on here about rust treatment. Clean off, panel wipes finish. Two days to four days.

Then primer if bare metal. Decent weather you might get two coats on, to increase thickness. One good day. I don't sand primer on bare metal.

Start by coating the roof, it may be patchy due rust etc, but assuming you get to a smooth surface with primers and undercoat, this could take  two to three days. 

You can also be doing the cabin sides early days if you want the coating to cure in order to sand. Read data sheet.

I found Sandtex ten year primer undercoat to be easy to use, quick to apply, on a good surface one coat would do, two is better if you have time to lightly hand sand wet and dry to 240 then 600 in between, but this is unlikely, as you need to wait, requires perfect drying conditions.

If you have not been able to get a smooth surface with primer you could try a thicker primer undercoat, however essentially, you need to start the job with everything on hand.

I only found Sandtex undercoat mid grey, but  used preferred colour in SML marine undercoat which is impervious and recommended as a matt topcoat for something like a roof. I did most of my roof with this, but  then used same colour topcoat along gutters, say four inches, giving extra thickness and allowing water to drain easier. It's easier to clean, but I assume matt finish is best on roof for those who use it to access lock ladders.

What was the question? It took me ten ( five working hour) days to do an acceptable job on a non rusty 57ft boat. 

A boat painter generally takes two weeks, but that needs to allow for not perfect weather, and he might have a more complex paint job. More complexity means more tapes, more paints, more time.

 

 

 

 

Edited by LadyG
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8 hours ago, Midnight said:

How soon after the first coat is it preferable before you to rub down?

How soon is it preferable to wait before second coat is applied?

 

On a bit of a timescale in dry dock.en with two topcoats.

Sand sand sand, get the surface smooth or the whole thing is a waste of time and money

You absolutely must get all old gloss sanded to matt, it's a huge area, you won't feel like doing it twice over after starting painting.

You must sand rust to bare and then coat with something like Kurust from Halfords for quick job assuming it's minor rust areas.

The chemical bond between one coat and another requires the second coat not to be fully cured. This time depends on temp and humidity. Read data sheet, I tend to start painting about eleven a.m., finish while it still feels warm. We are talking Dew Point.

I would avoid serious sanding after starting painting. If surface needs light sanding, you are creating dust, then needs wiped off, use panel wipes or the best tack rags.

If you want a super deep gloss surface this is not going to happen with only two coats of paint.  In my opinion you must prep, and you must use undercoat, the undercoat is to bond prepped, sanded surface to the gloss. Nowadays you can get  undercoat to same colour as top, or very slightly different which makes it easier to put on next coat. I use SML website, and like their marine paints, also rollers, and tapes.

If you are short of time, be prepared to spend a good twelve hours working on day one/two. 

The only way to do the job quickly is to spend longer days on prep to undercoat stage.  Three days to get most of it done and two days to finish topcoat, assuming it is solid colour. Using two colours on cabin sides adds two days. But it may be possible to do some bits outside on the cut, doors and front and back for example, so leave till last.

I have assumed perfect warm summer weather,  comfortable T shirt weather. 57ft boat.

PS make sure you tape windows properly. Use suitable paint but not Hammerite.

Edited by LadyG
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To answer your direct question about time between coats. Read the paint tin/data sheet because you will usually find two times for oil based paints (don't know about two pack). One is often about 16 hours when you can overcoat without  rubbing down a such and the other is several days, after the paint has hardened, and then you have to abrade and key the surface.

 

The major rubbing down is done before any paint is applied or if you are building up any pits.

 

If you are using the shorter time period it is normally said that you need to de-nib the surface. This is like a very mild rubbing down. As the paint will still not be really hard I would not use a power tool. I used the thin abrasive foam pads that come in boxes of 10, fine one side and medium the other, held onto a sanding block and done by hand. It does not take long. You will just be trying to remove  any insects or other nibs.

 

Also try to observe the air temperature recommendations. When I did mine at this time of year,  I had the side painted before about 9.30 am so the paint stayed wet long enough for the brush marks to flow out. Do not paint late into the afternoon or dew is likely to "fog" the new coat.

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9 hours ago, Midnight said:

How soon after the first coat is it preferable before you to rub down?

How soon is it preferable to wait before second coat is applied?

 

On a bit of a timescale in dry dock.

 

 

Impossible to answer without knowing what paint you mean.

 

Undercoat? Gloss? Brand? 

 

As Tony says, read the instructions on the tin to start with. If you tell the board what paint it is, someone may well have some good knowledge of it and advise how much you can push the limits for that particular product.

 

 

 

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At this time of year, you can rub down the following day, provided you haven't messed about with the paint too much. It will generally be ok. To test whether it is; if your sanding turns to powder, it's ok; if it creates small balls and clogs the sanding material, it isn't. 

 

If everything has been in your favour, dry and warm, paint at right thickness, you may even be able to sand on the same day. 

 

 

Edited by Higgs
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When I painted VS properly the first time I did it in a polytunnel with some help from others. Actual painting was done either pre 9.30 is or post 5pm depending upon air and surface temperature. In between it was ŕubbing down, masking up, removing/replacing fittings and a multitude of other jobs. Time wasn't wasted. It took 29 full man days over a 15 day window. 

Masons coach enamel. 

Edited by Slim
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  • 4 weeks later...
On 07/06/2022 at 07:20, LadyG said:

Sand sand sand, get the surface smooth or the whole thing is a waste of time and money

You absolutely must get all old gloss sanded to matt, it's a huge area, you won't feel like doing it twice over after starting painting.

You must sand rust to bare and then coat with something like Kurust from Halfords for quick job assuming it's minor rust areas.

The chemical bond between one coat and another requires the second coat not to be fully cured. This time depends on temp and humidity. Read data sheet, I tend to start painting about eleven a.m., finish while it still feels warm. We are talking Dew Point.

I would avoid serious sanding after starting painting. If surface needs light sanding, you are creating dust, then needs wiped off, use panel wipes or the best tack rags.

If you want a super deep gloss surface this is not going to happen with only two coats of paint.  In my opinion you must prep, and you must use undercoat, the undercoat is to bond prepped, sanded surface to the gloss. Nowadays you can get  undercoat to same colour as top, or very slightly different which makes it easier to put on next coat. I use SML website, and like their marine paints, also rollers, and tapes.

If you are short of time, be prepared to spend a good twelve hours working on day one/two. 

The only way to do the job quickly is to spend longer days on prep to undercoat stage.  Three days to get most of it done and two days to finish topcoat, assuming it is solid colour. Using two colours on cabin sides adds two days. But it may be possible to do some bits outside on the cut, doors and front and back for example, so leave till last.

I have assumed perfect warm summer weather,  comfortable T shirt weather. 57ft boat.

PS make sure you tape windows properly. Use suitable paint but not Hammerite.

 

Hempel or International Paints brands are known to be some of the best for marine paints, they also have a good range of primers and undercoats which u can use and they are specially designed for boats. To get rid of the rust I would use Fertan Runst Inhibitor.

Just now, SilentSailor said:

 

Hempel or International Paints brands are known to be some of the best for marine paints, they also have a good range of primers and undercoats which u can use and they are specially designed for boats. To get rid of the rust I would use Fertan Runst Inhibitor. Hope this helps!

 

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I painted my first boat GRP and followed instructions to the letter.

Result . Very poor .

Reason, I expected a full gloss finish and what I got was a sort of semi gloss BandQ household wall roller finish.

I know better now.

 

0

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  • 6 months later...

It's always best to buy your antifouling paint from a local marine store or chandlery in your area or the area where you keep your boat as they should know what would be the best paint for your boat/area. I would not buy anything from a DIY shop intended to be used on a boat which require special characteristics. Some of the most popular antifouling paints for example that you would find in almost every single chandlery are these ones here.

 

Hope this helps in the future other adventurers :D

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13 minutes ago, SilentSailor said:

It's always best to buy your antifouling paint from a local marine store or chandlery in your area or the area where you keep your boat as they should know what would be the best paint for your boat/area. I would not buy anything from a DIY shop intended to be used on a boat which require special characteristics. Some of the most popular antifouling paints for example that you would find in almost every single chandlery are these ones here.

 

Hope this helps in the future other adventurers :D

 

I think you may be on the wrong forum Canal boats do not use Antifouling.

 

Are you spamming the forum with your own products - your knowledge seems a little lacking.

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