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[Nordlys]

I would be interested to know how you boat builders finish your hull.
I have now applied 3 coats of Finishing Resin and while this dries hard and glossy there are still flaws in the overall finish appearance such as hollows and general uneveness.
What do you do at this stage to get the surface looking good enough to paint?
Filler?
Nordlys.

[newbe7]

With the finishing resin I use a blade to bring down the high spots and then sand I do this for all the coats I put on with each coat I try and get as smooth as I can making the work easier each time to finish and sand smooth it's all about how much work your willing to do to get it where you want to time is on your side before you decide to paint .
Rick

[Nordlys]

Each layer I apply is only brushed on, so its a relatively thin coating to start with, then I rub it down removing some of it!
There is an improvement with each layer I suppose but its far from even?
N

[John W E]

Hi there


A method I have used, quite successfully for many years, is, apply a first coating of resin and hardener to the hull and allow it just to go 'tacky'.  Then, over the top of that, place a layer of tissue matting or extremely fine woven roven (similar to what they use to cover aircraft wings with) and over the top of this I apply 3 further coatings of resin with hardener mixed - obviously allowing each coat to go 'tacky' quickly removing any high lumps with a blade from a Stanley knife carefully.  Then eventually finish off with a 3rd and final coating - and use an old bank card/plastic card to level off and use as a scraper.  Then allow it to harden for at least 2-3 days.   Start sanding back with a coarse grade oxide paper and then work through various grades of wet n dry and any low areas can be filled with car body filler or 'stopping' but don't forget when sanding - use a block - this prevents 'hollowing'.  Thing is to remember - doing it this way you are only creating a barrier to prevent water from entering the timber hull.   Don't forget polyester resin is not 100% waterproof - if left it will obviously absorb water so that is why we must put a further coating of paint or varnish over the top to further waterproof it.


If you have a look (I think its on Tug Cervia build - in the Masterclass on this Forum - I think there is a more detailed explanation of how I normally finish my hulls.


The only exception I don't paint the hull is when I am going to plate the hull with plasticard to represent shell plating.


John

[Mark T]

I would be interested to know how you boat builders finish your hull.
I have now applied 3 coats of Finishing Resin and while this dries hard and glossy there are still flaws in the overall finish appearance such as hollows and general uneveness.
What do you do at this stage to get the surface looking good enough to paint?
Filler?
Nordlys.

I use the following method


1.  Give the bare hull a coat of finishing resin applied with a 1" roller - You can't clean the roller so its a consumable
2.  After 48hrs wipe the surface over with IPA to remove the "fat" and lightly sand
3.  Apply another coat of finishing resin using a very fine woven cloth like they use on RC aircraft.  Apply using a 1" roller as before
4.  After 48hrs wipe the surface over with IPA to remove the "fat" and lightly sand
5.  Apply a final coat of finishing resin to fully fill the cloth again with a 1" roller
6.  After 72hrs wipe the surface again with IPA and sand to the finish that you want.


I have achieved a glass like finish using this method and all sanding should be done dry.  Don't be tempted to add water to the mix.  The final sanding of my Fairmount Alpine to me a week on and off - its a long careful process as you do not want to break through the cloth.  The results are well worth the effort.


Nordlys in your case I would just go for it and sand the whole thing down - it will take time.  If you still need to fill any hollows then use a polyester filler but this should have really been done before any resin hits the hull.  If you do need to use filler wipe the area over once roughed up with IPA as this will give you good adhesion.


Good luck mate 

[John W E]

hi there Mark


Not wanting to condemn anything but I am intrigued about removing the fat are you referring to excess Resin build-up?    Its just I have been out of the fibre glass profession now for a good few year and I know terminology and things have moved on since my day


The only other thing I would question is your method - you are relying upon what is known as a 'mechanical bond' where the resin has passed its green state and therefore going into its 'set' stage - so there may be a case of 'delamination' between the 2 layers of resin.   Highly unlikely but the case is there and dampness can get in between the layers.



The other thing is, I have always wet n dry polished with various grades of wet n dry and been able to achieve a good finish.


john

[Nordlys]

I haven't gone as far as using a fibre glass cloth layer, this would certainly have given the hull a more even appearance, didnt think of it to be honest!
You have given me a few ideas tho' to proceed with - thanks!
Sorry, whats IPA?  I usually drink that!
N

[NickelBelter]

I'm guessing by 'fat' he meant the wax esters that float to the surface when using polyester resin.  'IPA' would be isopropyl alcohol which removes that wax, or is supposed to, at least.  Laying resin on resin is no problem unless you don't remove all of this waxy blush, then you will for sure have issues with the second layer.

I use epoxy resin most of the time as there's no surface issues to deal with, just sand between coats.  Plus I can use it indoors without gassing myself. 

[Nordlys]

ps John . That hull looks very much like the one I am now working on! A 41inch Seaplane Tender 441
I would post a picture but my Tablet does not like the Copy process on here.I can put it in my album but not post it.
N

[John W E]

hi Nordlys


that's the hull of the RTTL which I built a few year ago - the build was on this Forum, but, due to the fact the Forum crashed / pics lost from the build - I cant seem to find any to replace them with.  The computer I use now is a different computer and when I tried to transfer everything from my old compy to this one a lot of stuff seemed to disappear into cyber space - some cyber person is running around with my pics !!!   


John

[Mark T]

hi there Mark


Not wanting to condemn anything but I am intrigued about removing the fat are you referring to excess Resin build-up?    Its just I have been out of the fibre glass profession now for a good few year and I know terminology and things have moved on since my day


The only other thing I would question is your method - you are relying upon what is known as a 'mechanical bond' where the resin has passed its green state and therefore going into its 'set' stage - so there may be a case of 'delamination' between the 2 layers of resin.   Highly unlikely but the case is there and dampness can get in between the layers.



The other thing is, I have always wet n dry polished with various grades of wet n dry and been able to achieve a good finish.


john

Hi John


I don't think anything has moved on I simply use the advise I was given by Bucks Finishing who make epoxy resin and are my supplier.  Have you noticed how epoxy resin seems sticky even after you have left it for a few days.  Apparently this is a wax thats floats to the surface which is far better explained by NickelBelter.  If you put another coat straight over this there maybe issues over time at least thats what I was advised.  IPA should remove most of this layer which can then be sanded without rubbing it in.


I also key each layer for the next layer by sanding but I understand  what you are saying and that makes sense too.  As of yet I have had no delamination using this technique but that does not mean that it may not happen in a few years.


Yes I agree that you can polish epoxy but thats if you want a clear finish, in fact this is probably what I'll do on my current build.  But - If your going to lay a coat of primer on stay away from water.  Primer absorbs water and nowadays you won't find a body shop sanding down for primer using water.

[Nordlys]

John, the hull shape that has emerged from my build is really very similar to your RTTL, I have learned a lesson to be rather more accurate cutting out the notches for the chines and stringers, I am struggling a little at this stage with inaccuracies due in part to  sketchy lines on the plan itself, leading to me cutting too shallow or too deep!  Nightmare!
Im hoping it will gradually turn into an acceptable effort with the aid of filler and paint - you know.
Thanks for the pictures, I will try to get one of my hull on here tomorrow.
N

[Nordlys]

Here are my two hull photos - Seaplane Tender 41" showing the resin finish.
Work in progress I think!
Nord.

[John W E]

hey that is looking canny mate 


How brave are ya?


you could rub it all back - so the hull is nice n smooth - and follow what I did with the RTTL build and also with the Air Sea Rescue hull - that's add an extra layer of mahogany planking over the top.   I purchased this from Jotika and it comes in 4mm wide by 0.5 mm thick - and it comes in one metre lengths in a pack of 10.  What I did was glue the strips on in the opposite direction to my first layer of planking - this represents the scale width planking of the original vessels.  Then, when you have finished planking the exterior of the hull, rub it down very carefully and give it two coats of Z Epoxy finishing resin.  This is not a polyester resin its an Epoxy resin.  This is nice n easy to work with.


Something to think about.


John

[Nordlys]

John,
The hull already consists of two layers of diagonal plywood planking with 3 coats of Z-Poxy Finishing Resin. Is this Resin not the same as you have recommended?
I would say its not that easy to rub back.
N

[John W E]

Hi Nordlys


I didn't realise you had used ZEpoxy, everyone thought you were using a polyester resin which is a different ball game.   ZEpoxy is waterproof.   What I suggest you do is rub it back down with oxide paper so you get rid of all the lumps and bumps and see what the finish looks like if you have sanded through back into the timber.


If you have, give a very thin coat of ZEpoxy and use an old bankcard to spread it thinly over the area and keep it smooth.    I wouldn't bother about adding tissue mat or woven roven material as with you putting two layers of plywood planking on - it should be built like a tank /skin like a rhino




I like the build - keep the pictures coming


John

[Nordlys]

Ive been rubbing it down for an hour now plus scraping with a blade, that works well, its starting to look a bit healthier already!
80g 120g and 180g paper has removed most of the imperfections, just left with areas that I will fill with body filler. Or Epoxy?
I think overall it is of tank like strength John!
Ive used Balsa at the bow which is not holding up too well, easier than planking in that area but nothing like as strong unfortunately.
N

[john44]

Hi Nordlys, on my whaleback build I used a balsa block shaped to the frames ( before planking)
And planked over it giving strength at the bow.


John

[Nordlys]

That sounds like a good idea. But how did you get the planking to match up to the adjacent layer of planks?
N