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Paint, Just how crazy is it to follow the system


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Ok so we've got 2 beams out of Catknapp at the moment for repair and i've been getting quite a bit of "feedback" from non-marine friends about how crazy we are for following the paint vendors instructions, we're pissing money away and getting no value from it, blah blah blah.

 

These beams required a crane to haul out our wheelhouse and pull them out, They are a royal PITA to do anything with so I'm not wanting to compromise their lifespan with short cuts, However, all this chatter has got me wondering if there's anything to it. We're using international 1 pack so the system as per International is 4 coats primer, 2 of undercoat (prekote) and 2-3 of toplac. Because of the beam repair mainly being caused by paint damage and water ingress we're doing on the top of everdure soaking and 105 coat over the top. 

 

It's alot of work but i dont want to be doing this again anytime inside the next 7-10 years. How many here when painting follow the vendors painting system? Do some just wing it with 1+1+1 of primer/under/topcoat?

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The beams are of wood, or?

 

Mine are and I have used epoxy throughout construction and protection. Epoxy is a *much* better moisture barrier than any paint system. Epoxy does not stand up to UV so paint is needed to block out UV. I use 2-part polyurethane directly on the epoxy. Re-paint when paint fades or you want to change colour scheme. This works for me and my boat is 30+ yeras old now.

 

Primers and undercoats are in my simple mind good for filling pores in putty and the like. They also help the topcoat by covering colour variations in putty and wood and whatever.

 

/Martin

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We used international on our hull, top sides and deck. Followed the instructions carefully. We used two pack though.

4 coats undercoat and then two primer sounds like a lot. It all depends on what you are painting over. They may be wood beams, but are you effectively painting over evedure / fibreglass resin?

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I am interested to know what your non boaty friends are suggesting re type of paint.

If it takes that much effort to remove the Beams, then I would seriously be looking at a 2 pot paint. Single pots will give a service life of at least 5yrs. If really looked after, you may get 7 to 10.
2 Pot paints will give you a service life of 15yrs and you may even get double that, if really looked after. Plus any 2 component coating usually takes the knocks and scraps much better.

Epoxies tend to be hard and can often chip. They are excellent on hard surfaces like fibre glass, but not quite so great on softer surfaces like Timber. They are excellent at being water barriers and barriers to anything for that matter. Not so great re Gloss and UV as Urathanes are.
Polyurathanes are flexible and very very hard wearing/scratch resistant coatings and are able to high gloss finishes.

"Systems" are to give you the best of protection for each and every step. While you can get coatings that are multi coats that do everything these days, that is usually only for simple situations. Even those types, if you read the nitty gritty info, you will find that in difficult situations, they will advise some kind of primer or undercoat or both.
So for a system, the Manufacturer has considered each step. i.e, how to protect the substrate material the best way that can be, how to adhere to it the best way, and how to provide the surface for the next coat to adhere to and get the best result from the next coat above. So their "system" may require a Primer, a Barrier, Undercoat/surfacer and a top coat perhaps. Multi systems are still the best way to get the maximum level of protection
 

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Loads of food for thought here. We were hoping to avoid 2pack systems but it's worth considering again :)

 

Most of the people were very much in the school of thought to slap on what ever's on sale and 1-2 coats primer then 1+1 under/top coat. 4 coats of primer is whats in the international guide so it's what we'll keep doing :)

 

In my testing, we found that straight wests at 30c would only penetrate around 1mm of a douglas fir offcut we had, When using everdure we got 4-5mm of penetration. We were concerned it wouldn't seal 100% so we have done a thin coat of wests after ruffing up the surface with some 180grit. The beams aren't meant to flex as the lashing are meant to take up the movement - We've not found any cracking so much as we have found peeling and delamination of the paint from the timber, The water ingress has come from screws for the wear pads not being epoxied in right.

 

Thankfully the beams are protected from most UV and impact damage by being surrounded by decking at the top of the beam so without flexing and without being damaged by bumps and knocks it should be fairly long lasting, Only time will tell!

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These are the wear pads that position the beam, So far I haven't ID'ed them but it's some sort of fiberglass and red resin, Flex's pretty well so I was thinking it might be a phenolic resin type. Anyone seen them before? I need to get a few new ones

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I did look at interprotect but ruled it out early on due to us wanting to stick with 1 pack paints, In the end we went with Everdure 50/20/10/0 + West 105, This seems to be a common way these boats are built. Some skip the evedure and I'm pretty sure 90% of our beam damage wouldn't be here if they had used everdure

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Neat Epoxy Resin does not make a good primer/Undercoat or whatever you want to call it. Even when warmed, the penetration of Epoxy into bare timber is not good.
Yes it is true that Evidure is porous due to the Thinners evaporating. That was only ever an issue when it was used as a clear coat. As a penetrant into ply, it works well and if it then gets an undercoat over it, the coating is sealed, so no problem. It is good at making a soft timber hard. But for anything else, there is not a lot of point when a Primer/undercoat does the same thing or even better. By the way, Evidure is stupid expensive. Although there are other brands on the market a lot cheaper. However, mixing 10% Epoxy thinners into Resin makes Evidure and that is a lot cheaper.
An undercoat has several important points. The reason it has a Solvent in it is to do the same as thinner in Resin. It causes the Undercoat to penetrate the Timber in two ways. First is simply viscosity allowing it to penetrate the pores and fibres and secondly, it causes the Fibres to swell slightly and thus act as "keys" to the coating. As the Solvent evaporates away, the fibres shrink again and lock the coating to itself. This is one thing neat Epoxy resin does not do by the way. Simply because Resin does not have a solvent. It relies purely on it's low viscosity to lock to fibres. Of course, not all Epoxy resin is equal. Some brands do this better than others. Some will say there is even a substantial difference between International and West in this instance. Although some like one and some like the other.
Re the bending a cracking, this is another major difference in brands. Some go rigid and will crack very easily and others can be extremely flexible.
Back to undercoats. These usually have the one important factor of being high build and easily sandable. Undercoat is the coating that you should concentrate on getting the Hull perfectly fair ready for the top coat. NEVER appky a top coat till you are totally happy with the Undercoats finish. A Top coat will ALWAYS show up every little defect by making it 10x more obvious than it was when it was a defect in just the undercoat.
In my view, the saying, use the right tool for the job is important in Painting also. I consider Epoxy to be a product for Fibre glassing, making Glue and Fairing. Not as a Paint.
Primers can be important in regards to the situation they are being asked to be applied in. Such as adhering to Steel, sealing it and protecting the steel from Rust. This may be done by having Zinc carried in the Primer. Or it may simply be a sealant, stopping water from making it's way through to the steel. Each kind of substrate may require a Primer for a particular reason. Most Manufacturers have "systems" for every type of substrate and the way that substrate maybe used. Such as above or below waterline for instance.
 

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