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Author Topic: How to create a smooth finish  (Read 6030 times)

bbdave

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How to create a smooth finish
« on: April 03, 2015, 08:48:52 am »

I have just finished glassing a balsa 1 meter yacht hull with 100g cloth I now have the textured finish how best do I get a smooth finish I am trying not to add weight but I think if I wet and dry it I will take to much cloth away. Shall I add a thin coat of resin and sand back a couple of coats may be required or will a clear varnish be a better option?


Dave
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inertia

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Re: How to create a smooth finish
« Reply #1 on: April 03, 2015, 09:27:33 am »

Dave
I would add the resin and rub back. If you sand through the cloth from where you are now then you'll have to recoat with resin anyway. You can thin out epoxy with rubbing alcohol (isopropyl alcohol) to make it easier to brush on thinly and I have found that silicon-carbide paper is "kinder" than W&D, at least for flatting down http://www.toolbank.com/0/p/FAIARS115180
If you are going to use an opaque paint finish then you could also use a high-build primer/filler prior to primer and gloss.
DM
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JimG

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Re: How to create a smooth finish
« Reply #2 on: April 03, 2015, 10:38:06 am »

Dave,
from my experience in skinning planes with glass.
First give a light sanding to the surface to make sure that it is clean and wax free. Then paint on a coat of epoxy, no need to thin it down as you will sand away much of it. Leave it for several days to make sure that the epoxy has hardened completely or it will tend to clog up the paper even when used wet. Then give it a coat of spray primer before sanding, this will help to show up any high spots in the resin and help in achieving a smooth finish. When the primer is all removed you might want to give it another light spray of primer and re-sand to check for smoothness. You can then give it a light sanding with finer paper to get a better finish, you can get a near polished finished using very fine paper this way.

Jim
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john44

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Re: How to create a smooth finish
« Reply #3 on: April 03, 2015, 11:02:17 am »

Hi, Dave, as above, I use silicone carbide or wet&dry. Do not use sandpaper
I always use them wet when rubbing
Down resin, helps keep dust down, but wear a mask anyway :-))  I use a block shaped
As appropriate, spray the hull, and sanding block with water, rub the sanding block on a bar of soap,
rub the bar of soap over the hull and start sanding.Using the soap gives the sanding block better
Suction to the hull.


John
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bbdave

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Re: How to create a smooth finish
« Reply #4 on: April 03, 2015, 12:20:25 pm »

Ok thanks after the final rub down will a spray of clear lacquer keep the clarity I'd like to show the planking if possible


Dave
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Nordlys

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Re: How to create a smooth finish
« Reply #5 on: April 03, 2015, 05:13:22 pm »

Dave, I have fibre glassed a number of my boats now as they were ageing and the ply delaminating. At the stage you are now at
I wouldn't expect to see much of the hull planking through the resin and glass cloth?
Rightly or not I sand down the resin/glass finish as even as I can then use a filler to fill in any remaining hollows etc.
Followed by many coats of primer and paint and sometimes a varnish to seal further.
All very time consuming as coats need to dry thoroughly really.
There are also many posts on Mayhem that recommend NOT to use wet & dry.
N.
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John W E

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Re: How to create a smooth finish
« Reply #6 on: April 03, 2015, 05:23:34 pm »

hi there Dave

Have a quick look at this link

http://www.modelboatmayhem.co.uk/forum/index.php/topic,20758.50.html

its the RTTL hull which I built a few moons ago :-) and although this is double diagonally planked (inner planks 1.5 mm thick x approx. 10 mm wide Obech and outer planking was 0.5 mm thick x 5.00 mm wide Mahogany) and had 3 coatings of Z-Poxy finishing resin.   Each coat was rubbed down with various grades of wetndry and then it was finished off with a very fine wetndry - I noticed on the build that some of the pics are missing on the RTTL build - but if you click onto the little square it seems to bring the pic on the separate page - at least it does on my candle powered box :-)

aye
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bbdave

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Re: How to create a smooth finish
« Reply #7 on: April 03, 2015, 06:08:06 pm »

Dave, I have fibre glassed a number of my boats now as they were ageing and the ply delaminating. At the stage you are now at
I wouldn't expect to see much of the hull planking through the resin and glass cloth?
Rightly or not I sand down the resin/glass finish as even as I can then use a filler to fill in any remaining hollows etc.
Followed by many coats of primer and paint and sometimes a varnish to seal further.
All very time consuming as coats need to dry thoroughly really.
There are also many posts on Mayhem that recommend NOT to use wet & dry.
N.


The planking is quite visible through the cloth and resin as they cure clear.


I have wet and dried it to key it and wiped it off with IPA , i have added a coat of resin I'll let you know how it looks after a rub down.


Dave
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Netleyned

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Re: How to create a smooth finish
« Reply #8 on: April 03, 2015, 06:19:32 pm »

A photo of the work so far would be appreciated
Dave.

Ned
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bbdave

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Re: How to create a smooth finish
« Reply #9 on: April 03, 2015, 09:00:00 pm »

Ok here's work so far this evening


Dave
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carlmt

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Re: How to create a smooth finish
« Reply #10 on: April 03, 2015, 10:53:08 pm »

That's a tidy spot of planking  :-))
 
No wonder you would want to keep it visible!!!!
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