Model Boat Mayhem
Technical, Techniques, Hints, and Tips => GRP & Epoxy => Topic started by: Garabaldy on January 10, 2009, 11:05:54 pm
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Is this ok to do? All the frames on my current build have a coat of white paint on one side as the wood was salvaged from a building site. Will i be safe enough to just glass over them or should i sand the paint off first? I really want to avoid doing this as it will take days.
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You should really get rid of the paint as any type of resin will not stick to paint,can you possibly paint strip the paint with nitromours or similar
Stavros
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Hi all.....from experience you must sand prior to any application of a polyester resin.............remember the sanding <*< is to take any smooth surface away & provide a KEYING surface for the polyester to lock into...... :-)) so the rougher [within reason] the better...Derek
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would turps be ok to aid in getting rid of the paint? It is only the frames which will be on the inside of the hull but i would be much happier if i could glass the inside to add strength. hmmmm i should really get the paint off so i can glass it.
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would turps be ok to aid in getting rid of the paint? It is only the frames which will be on the inside of the hull but i would be much happier if i could glass the inside to add strength. hmmmm i should really get the paint off so i can glass it.
No, turps will not remove dried paint.
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Garabaldy
Why do you need to glass over the frames and inside of the hull?
Bob
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just to increase the strength of the hull. I suppose i do not NEED to but i would like to.
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Garabaldy
Unfortunately as has been stated above you will need to provide a key for the resin.
Bob
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Yes, i feared this. Do i need to remove ALL the paint? I just removed all the paint from one side on frame 5. To touch the sanded side is far smoother than the painted side. I am considering just leaving the paint. A good layer of glass on the outside of the hull should be plenty strong.....
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Part of the key is that the resin will "soak" into the surface of the wood via osmosis.
Where the wood is painted the resin can only adhere to the paint so the strength can only be as good as the paint adhesion on the wood.
Bob
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Ahhhh. I will go and think about this. Good info though. Thank you all.
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Slightly off topic but I'll ask any way. Why do people want to resin/fibreglass the inside of hulls? I'm not trying to be rude or anything but it seems odd to me to fibreglass the inside of the hull then spend hours filling and sanding the outside. Surly it's better to glass the outside and then you get the strength and finish in one go. Or am I missing something?
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It just strengthens and waterproofs the hull on the inside from leaks, spills and oil etc.
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hi all,
I ended up sanding all of my frames. I got every last bit of paint off. It was a painfull 4 evenings with the sander but i got there. Im glad i did it.
As Martin says. Thats exactly why im doing it. Mainly for the strength. Im building from plans which i nearly doubled in size with a photo copier so the frames in the middle are quite far apart. Theres alot of flex in the wood so putting GRP on the inside and out will hopefully make it bom proof. I will probably use the fibreglass matt inside hull but im not that far on yet.