"Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

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Aquarius
Posts: 105
Joined: Thu Jul 13, 2017 11:08 am
Location: Woodbridge Suffolk

"Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

Post by Aquarius » Wed Aug 16, 2017 9:40 pm

Has anyone had any luck with oxalic acid to remove the dreaded black stains where the varnish failed?
CVRDA eligible:
1962(?) Firefly F3163 "Aquarius"
1946 International Fourteen K478 "Galatea"
Not CVRDA eligible:
1991(?) Nethercot IC K229, "Ogaf the Unbearable"
Squib. possibly number 251, "Squirt"

chris
Posts: 2419
Joined: Sat Sep 18, 2004 7:43 pm
Location: somerset

Re: "Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

Post by chris » Sun Aug 20, 2017 4:41 pm

yes a few appliocations completely removed a very black area onn aan Albi - just remeber it is acid!

Aquarius
Posts: 105
Joined: Thu Jul 13, 2017 11:08 am
Location: Woodbridge Suffolk

Re: "Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

Post by Aquarius » Sun Aug 20, 2017 10:31 pm

chris wrote:yes a few appliocations completely removed a very black area onn aan Albi - just remeber it is acid!
Thanks Chris. First application has turned "black" to "grey" and incidentally I noticed that it has a cheering up effect on the colour of the surrounding intact wood.

The Firefly is sitting in the shed ahead of the Fourteen, both scraped back and getting detail attention and they make an interesting study.

The Y shaped keelband bits in way of the centreboard case are the same, the rudder hangings are the same and so, to my surprise, is the space between gudgeon and pintle which means that the spare Firefly fixed "duck's foot" rudder is now a spare Fourteen rudder!

The Fourteen had one black spot in the lower transom in way of the drain holes (also identical!) and that vanished with one application.

The bad news is that the Firefly has delamination in the centrecase sides. It hasn't been leaking, and I only found it when scraping the bottom...
CVRDA eligible:
1962(?) Firefly F3163 "Aquarius"
1946 International Fourteen K478 "Galatea"
Not CVRDA eligible:
1991(?) Nethercot IC K229, "Ogaf the Unbearable"
Squib. possibly number 251, "Squirt"

chris
Posts: 2419
Joined: Sat Sep 18, 2004 7:43 pm
Location: somerset

Re: "Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

Post by chris » Mon Aug 21, 2017 8:26 am

Yes Oxalic usually works very well on solid mahogany. On a moulded hull the glue will have penetrated the veneer which can make it more difficult.

Aquarius
Posts: 105
Joined: Thu Jul 13, 2017 11:08 am
Location: Woodbridge Suffolk

Re: "Out, Damned Spot!" (oxalic acid on a Fairey agba hull?)

Post by Aquarius » Wed Aug 23, 2017 3:33 pm

chris wrote:Yes Oxalic usually works very well on solid mahogany. On a moulded hull the glue will have penetrated the veneer which can make it more difficult.
Thanks again.

This is after two applications:

Image

The worst bit (had been black):

Image

Should I have another go? Or is this as good as it gets?

Here's the Fourteen's transom "before":

Image

And "after" (sorry about the varnish run it's the first coat...)


Image


Thanks

Andrew
CVRDA eligible:
1962(?) Firefly F3163 "Aquarius"
1946 International Fourteen K478 "Galatea"
Not CVRDA eligible:
1991(?) Nethercot IC K229, "Ogaf the Unbearable"
Squib. possibly number 251, "Squirt"

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