Thread: What preparation for painting the topsides?

Hopefully a member here PAR will be along to comment but in the mean time I suggest 80 grit paper is all that's need to provide a good key for the primer on bare wood.

Thanks m2c11w. Is the idea to have it just slightly coarse?

Originally Posted by Maladjusted

Thanks m2c11w. Is the idea to have it just slightly coarse?

That's my understanding a slightly scuffed surface will allow some penetration of the surface thus promoting good adhesion assuming a sound, clean surface free of contamination to start with.
What sort of planking and was the previous primer water based.

She's carvel and I think the last primer was water-based. I'll check on that though..

If the paint is well stuck, under the screwed up paint, then just sand off the offending layers and prep her for more paint. Compatibility issues can arise, so a primer is a wise option though often unnecessary.

Paint peeling is almost always from bad prep, as are most paint related issues other then age or damage (like UV). Water based paints are fairly cheap, in fact the cheapest of all paints, but also not very durable compared to other paint types. Paint is one of those things where you do usually get what you pay for. The stuff I use is a 4 part "system" and costs about $300 a gallon (wholesale prices) just for the "resin". This doesn't include the activators, reducers, drying agents and other chemicals necessary to produce a finished product. In it's defense, this stuff is nearly bullet proof, looks like glass when cured, is very hard, holds it's gloss longer then anything, very moisture vapor resistant and generally is the stuff the big boys play with.

Most don't need, can't apply nor want to purchase these types of paints. Again the acrylics (latex, water based) are at the bottom of the list in terms of price, durability, gloss retention, etc.

Next up the list are modified acrylics, which have slightly better preformance.

About the same preformance can be had with the straight, traditional alkyds (oil based). These are the old school enamels and work well for most folks, though they're solvent based paints, which some find offensive to work with. Many thousands of yachts have this type of paint on them, some with lead in them.

Next up are the modified alkyds, which have some cute chemicals added to improve hardness, water resistance, gloss, etc.

The last of the most common paints are the single part polyurethanes. These are actually very highly modified alkyds in most cases. They are so highly modified that some need specialty thinners, etc. These paints preform very well and are the best bang for the dollar for the backyard boat builder. They out shin all the others listed above, are more durable and harder.

The last group of paints are the multi part polyurethanes, epoxies and other specialty coatings (like cyanoacetate activated polys). These generally are priced much higher, are more difficult to apply, require weird chemicals to thin them and generally make you cuss a lot. They are very durable, the highest gloss you can get, very hard, some very flexible and of course ridiculously costly.

My customers insist on a particular quality of finish, which often forces me to use the expensive stuff. Given a choice I would rather use the single part polyurethanes for their ease of application, cost and durability.

Lastly, you don't have to sand back to raw wood. In fact, it's probably better if you didn't, because you'll remove fairing compound if there is any and you'll have to seal the wood, which raises a whole new set of issues. Yes, varnished wood is lovely, especially when someone else has to maintain it . . .

I'd like to point out that the higher the gloss, the more work is required to prepare for painting. Every bump, lump, dip and ripple in your boat is going to be highlighted by the glorious shine of that ever so expensive paint.

Also, timber boats live, the wood expands and contracts and the harder the paint, the sooner the cracks begin to appear. So what may be sweet on a GRP/ally/steel boat may not be the best option on a carvel job.

International, Jotun and Hempel are all easily available in Oz and have some great products for our boats. (I like Jotun myself). For that matter, a good quality latex housepaint will do a fair job although you'll be repainting slightly more often.

For my money, the paint only needs to look good from 20 feet... any closer and you should be thinking more about climbing aboard and heading out

Originally Posted by Darce

For my money, the paint only needs to look good from 20 feet...

Thanks, that's great support for what I now believe. It will save lots on the amount of fairing filler that has to go between my carpentry and the paint.

Use a high gloss under the final coats (even if these happen to be satin or flat) of paint. High gloss paint is much more water resistant then satin. Flat paints actually absorb moisture, so if you want satin or flat finishes, use high gloss first then top coat this with flat or satin.

Originally Posted by PAR

The last of the most common paints are the single part polyurethanes. These are actually very highly modified alkyds in most cases. They are so highly modified that some need specialty thinners, etc. These paints preform very well and are the best bang for the dollar for the backyard boat builder. They out shin all the others listed above, are more durable and harder.

Any members in Australia know what the leading paints (best quality) are, available locally, that meet the above category description ?

Looking at a couple of local chandlery catalogues (Whitworths and Bias Boating), I see a few paints that could be examples:
- Norglass Gloss Enamel
- Hempel Brilliant Gloss Enamel
- Nautical Enamel topcoat (Whitworths; rumoured to come from International)

But these may or may not be the best quality examples; anyone with experience able to comment on these, or other, superior examples in Oz?


Also, I notice that International (Interlux) has a product called "Toplac Gloss" which is described as a "Silicone Alkyd Enamel" ( ... bit ironic, isn't it - silicone and paint don't usually get along so well).
Where would that sit relative to Polyurethane Alkyd Enamels?

My experience is confined to Norglass premium enamel and Interlux Brightsides both are easy to use flow out and level well using a roller and show great gloss quality.
I was at the local chandlery yesterday and they are converting their stock to Norglass stating supply and cost of Interlux product was becoming difficult, don't know how true that might be but Norglass is reasonably priced compared to the others.

I'd recommend Jotun paints as well