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Author Topic: sanding sealing and waterproofing  (Read 343 times)

Philbyuk

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sanding sealing and waterproofing
« on: May 01, 2020, 08:18:20 PM »

hi there all , not far off sealing  my boat .. got 2 tins of sanding sealer ,but realised they are  cellulose based , i'm going to be painting hull, decks etc with acrylic paint. is this going to be a problem?
also will sanding sealer  help waterproof the wood  inside and out , or better to try something else . suggestions very welcome.
Thanks in advance.
Phil .
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JimG

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Re: sanding sealing and waterproofing
« Reply #1 on: May 01, 2020, 09:03:22 PM »

Acrylic over cellulose generally not a problem. (the reverse is) However best to leave it for at least a week for the cellulose solvent to fully evaporate before overpainting with acrylic. If you don't the surface of the acrylic will probably crinkle and need sanded back to the sealer. Sanding sealer should waterproof the wood as long as you don't sand through the surface in your preparation before add ing the top coat. For the hull inside I would prefer to use thin finishing epoxy which will soak into the wood and harden the surface.
Jim
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coch y bonddu

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Re: sanding sealing and waterproofing
« Reply #2 on: May 01, 2020, 09:41:43 PM »

why take the chance of a reaction simply get some acrylic laquer spray and give the hull 3 coats this will seal the wood for you and defo as Jimg states finishing epoxy on the inside of the hull




Dave
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Philbyuk

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Re: sanding sealing and waterproofing
« Reply #3 on: May 01, 2020, 10:58:40 PM »

would fibre glass resin work as good as epoxy resin finish ? a;so if i use the sanding sealer and prime before painting be ok ?
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RST

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Re: sanding sealing and waterproofing
« Reply #4 on: May 01, 2020, 11:22:11 PM »

...been a few posts about sanding sealer recently.  I don't ever remember it being a "covering" or a "coating".  I mean it's fantastic for sealing things "hairy" like balsa or any raggedy edge end grain materials but never heard of it as a full "coating" until recently -when folk are perhaps rightly to say not to, because, maybe its just me but I never saw it used that way before over a big surface on a model?

...Polyester versus epoxy.  Well enough out there already.
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Tug Fanatic

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Re: sanding sealing and waterproofing
« Reply #5 on: May 02, 2020, 08:58:43 AM »

would fibre glass resin work as good as epoxy resin finish ?....................

This is my pinion & others will tell you different.

The answer is no!

The other thing is that the epoxy resin that you use needs to be a thin epoxy (a laminating or finishing type). I would never recommend anyone to thin a thick epoxy resin.
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tonyH

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Re: sanding sealing and waterproofing
« Reply #6 on: May 02, 2020, 09:56:43 AM »

I know it's a bit of a side issue but does sealing wood with sealer affect the stickability of the wood with either epoxy or superglue?
Cheers
Tony
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Tug Fanatic

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Re: sanding sealing and waterproofing
« Reply #7 on: May 02, 2020, 10:11:16 AM »

I know it's a bit of a side issue but does sealing wood with sealer affect the stickability of the wood with either epoxy or superglue?
Cheers
Tony

Perhaps you should extend that to any of the common adhesives after sanding sealer. I would identify 2 problems for you to consider:

1. I would observe that there are at least two different types of sanding sealer & their adhesive performance probably differs.

2. I suspect that there is a real lack of data - I certainly have not seen any. Sticking at all and sticking without changing adhesion performance are two different things.
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Gardener

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Re: sanding sealing and waterproofing
« Reply #8 on: May 02, 2020, 10:44:58 AM »

Used Deluxe water based sanding sealer with Acrylic paint over it on my Springer  no problems !
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Gardener

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tonyH

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Re: sanding sealing and waterproofing
« Reply #10 on: May 02, 2020, 10:52:04 AM »

Thanks Tug,
I've got to fit wood (1mm ply or 6mmx1mm mahogany strip) bulwark capping to the edge of a f/glass hull.  The wall thickness is about 2mm so it's fairly good area wise. Normally I'd prep the wood with cellulose sanding sealer before fitting because it would be pretty well impossible to finish the wood properly in place, so........?
Tony
Sorry Gardener but d/l doesn't mention any reaction with the adhesive.
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Gardener

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Re: sanding sealing and waterproofing
« Reply #11 on: May 02, 2020, 10:59:06 AM »

Just answering original question !
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tonyH

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Re: sanding sealing and waterproofing
« Reply #12 on: May 02, 2020, 02:55:36 PM »

Sorry old chap,  just got carried away!
 %) Tony
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unbuiltnautilus

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Re: sanding sealing and waterproofing
« Reply #13 on: May 02, 2020, 05:30:56 PM »

...been a few posts about sanding sealer recently.  I don't ever remember it being a "covering" or a "coating".  I mean it's fantastic for sealing things "hairy" like balsa or any raggedy edge end grain materials but never heard of it as a full "coating" until recently -when folk are perhaps rightly to say not to, because, maybe its just me but I never saw it used that way before over a big surface on a model?

...Polyester versus epoxy.  Well enough out there already.




I have been using cellulose sanding sealer for more years than I care to remember as first coats ( usually three or more ) on timber/plywood models. Often slightly thinning the first coat for timber penetration. Then followed with spray or brush on primer, finally finishing off with either enamel or acrylic top coats. No adverse reaction problems yet!


The photos show my latest build, LCT-6 from 4mm ply over a glassfibre donor hull. The timber was sanded down and filled first. Then I tried Guild Materials Spray Sanding Sealer. It seemed counter intuitive to have a grain filling cellulose based product in a spray can, it wasn't an issue and it worked very well. The top coats were also from Guild, their light grey enamel aerosol, plus their brush on dark grey enamel. These products seem to be a replacement for the old Flair paints, and I thought I would give them a try. Happy so far.


The rest of the job will be a mix of brush on enamels and acrylics for detailing, plus whatever works for weathering effects.

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