Thread: How much primer and paint?

on my 14' Yellowtail,for the exteria of the hull i used 2.5 liters of epoxy primer but most of this gets sanded off getting a smooth finish for the top coat.
for the top coat i used only 1 litre of two part polyurathane gloss.
for the interia of the hull i'm not sure but it was definetly less as i left the insides of the lockers un-painted.

so i think your calculation won't be that far off

Recommend primer (if the wood is bare) and undercoat to get the boat to an even colour before moving to topcoats. Topcoats are usually quite transparent so patchiness of the boat will show through unless you use undercoats. You need LOTS of topcoats to cover patchiness

Mik, thanks for the tips.

The hull has been painted previously (with a grep primer and a top coat) and now im in the process of stripping it back. I do have some remnents of that grey primer that i cant seem to get rid of, even with a bit of sanding.

So far in my research i have seen people just use primer or undercoat, not both. I guess thats what had me stumped. Can you get away with a couple of coats of undercoat/primer or is it essential to use both? Reason i ask this is because of budget, both products are not cheap! I am looking at using International undercoat/primer and top coat. They seem to be a reasonable price and give a great finish.

Another question i have is, i have had a go at trying to remove what looks like a varnish from the interior of the dinghy. The coating seems to have been exposed to the elements at some stage and is now beginning to peel and flake. I have tried sanding and some heat but nothing seems to strip it back enough that seems good to prime and paint. Could it be epoxy? Should i try some chemical strippers? Is sanding it enough to allow me to paint? Once this finish is removed im going to paint rather than varnish or epoxy coat.

Any help would be apreciated

Cheers

Ace

Depends on the paint system. Also I think that in the USA people use a lot of house paint (2 products) rather than boat paint (3 different products for one application) and tend not to use epoxy. Add to that that in the USA primer seems to be what we call undercoat and it gets confusing.

If you use epoxy first this is the order
epoxy
undercoat (usually white)
top coat

If you use primer its purpose is to soak in and also give a smooth sanding surface to fill the wood grain.
primer - usually grey, or underwater areas for boats being kept in the water a metallic pink
undercoat - usually white
topcoat.

Going two pot the primer is normally a high build with no primer.

I do tend to follow the manufacturer's directions closely if not using epoxy sealing as the base so will follow their scheme of primer undercoat and top coat.

MIK

What would your opinion be on the flaking varnish/epoxy (whch ever it maybe)? What would be the best course of acton?

Cheers

Originally Posted by highace1

What would your opinion be on the flaking varnish/epoxy (whch ever it maybe)? What would be the best course of acton?

Cheers

You just need heat and a good scraper. Even epoxy softens with heat.

You say you've tried 'a little heat', well, try some more. Hell, find an area that's nowhere near any joins and really get stuck into it - I'm not saying you have to do that but I remember back to my first efforts and I grossly underestimated just how hot I could get things without doing any damage (spent most of the job doing it the hard way coz I wasn't heavy handed enough with the heat gun dammit) and I'm wondering if you're not making the same mistake.

Richard

All i can do is give it a go! MORE MORE MORE HEAT! he he

Thanks for the tips

More question to come no doubt

Ace

Is it important that i remove every last bit of paint or primer? No matter how much i sand or scrape i cant seem to ge it off.

Cheers

Ace

If you are epoxy sealing it I would target to have about 95% of the surface bare and no paint build up left at all.

If just painting - then no build up left, but some patchiness is OK providing you are really sure the paint is well stuck to the hull.

MIK

Whats the norm as far as coats are concerned for priming? 1, 2 or 3 coats. Just trying to get an idea of how much paint i will need. This boat painting thing aint cheap!

Im taking a guess that the size of the NS14, i will need a bit more than 2L but less than 4L of primer and undercoat.

For something that is not constantly in the water, is it necessary to have a primer? (roll eyes.....he's trying to get out of spending money he he)

Ace

Follow the manufacturer's directions. I always do except when going over an epoxy coated surface, where i know I can eliminate the primer.

With the NS I would go for one coat of primer on bare wood normally and if I went through when sanding i would just do a little patch and sand it down smooth later.

Sanding is the big secret. YOu have to use a sander with a flat base or a block. The more sanding you do .... the better the result.

MIK

It work out better to epoxy first and undercoat then paint. For a boat of this size how many litres of epoxy would i need? That would be to seal up the hull and the interior.

Cheers

Ace

Three coats are recommended. Read the FAQ I posted the link to about applying wet on wet and the section on the Sabre dinghy.
FAQ - Boat Building and Repair Methods - Plywood Epoxy Fibreglass Cedar Strip - Michael Storer Wooden Boat Plans

the coverage is about 12 sq metres a litre per coat if you roll it with the right rollers. YOu can use two or three times that if you try to do it with a brush.

I would probably sort out the outside of the hull with the epoxy as it is easy to do, but I think doing the whole epoxy thing would be overcapitalising the boat (spending too much for what the boat is worth).. Epoxy and light glass can be useful if the ply is splitting or cracking anywhere, though if the area is extensive then it can be easier to replace the ply sometimes.

It depends on your feeling about the boat - if you love it and want to keep it for a long time (NS14s are pretty loveable) then it is worth spending more on materials.

I think to keep the cost down I would do any repairs with the epoxy but just use a primer, undercoat and topcoat.

MIK

Does anyone have a link to the colours that Norglass produce? I cant seem to find anything on the website.

Cheers

Ace