Blotches on my Jarrah

[Pete]

Help!!
I have just finished this very nice sofa table for SWMBO and started the finishing steps. I had decided on a high gloss polyurethane and after reading the Feast Watson instruction commenced treating the surface with Fungishield. Applied well, looked good wet.
However, when I came to start sanding it back today I see that it is covered in little black blotches. Not on all of the faces just where you look end on into the grain. I assume that the fungisheild has reacted with something in the timber. Any ideas on what's happened and more importantly how do I fix it?

Thanks in advance,
Pete

[Shane Watson]

I think your first mistake was to follow there directions...... http://ubb.ubeaut.com.au/ubb/wink.gif Why they would recommend the use of a fungicide is something I would question.

I would recommend contacting them direct, ask to speak to a technical representative and talk to them about the process you used and the problems you have encountered. If they can't help you, they shouldn't be working for the company!

By the way, I am in no way associated with them, even though they share my name! http://ubb.ubeaut.com.au/ubb/biggrin.gif

Cheers!



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Shane Watson..

Combine Love & Skill & You Can Expect A Masterpiece!

[Pete]

Well I read the instructions again and the fungishield is a dual purpose antifungal treatment and primer. I have looked at the blotches in more detail and they appear to go well into the timber. They do not go away with sanding. Looking at some of the boards it appears that they follow a line perpendicular to the radial growth pattern of the timber. I'm starting to wonder if the fungishield has been wicked into cracks and is simply more concentrated in these areas.
I treated a couple of scraps of Jarrah I had left in an attempt to replicate the problem and of course.... Nothing happened! So, I've dropped an e-mail to Orica in the vain hope that they understand their product and its effect on timber.

In order to minimise the pain for the next time what would you guys recommend as a durable high gloss finish for Jarrah? The next job is a cabinet to hide the idiot box.

Cheers,
Peter

[Shane Watson]

Hmmmmm....primer.... Your not painting your car with this stuff are you?? http://ubb.ubeaut.com.au/ubb/confused.gif Maybe thats what its intended for http://ubb.ubeaut.com.au/ubb/wink.gif

If you want somthing easy to work and fairly durable, I would suggest maybe using a basic Nitrocellulose (sp?) Lacquer. Such as Mirotone, wattyl, croda etc. This stuff is used predominently by most furniture production factories. So obviously it is cost effective... And these companies also produce poly-u lacquers if you still want to go that way. Or there is always 2-part lacquers/poly-u's. One good thing about N/C lacquer is that it can be rubbed with a lacquer rubber in a similar fashion to Shellac. Technically its called pulling http://ubb.ubeaut.com.au/ubb/eek.gif Its done using a pulling liquid(which pretty basically is ethanol and n/c reducer) and rubber.

Obviously this fungy stuff had reacted to something in the timber. So will be interesting to hear what response you get from Feast Watson should you decide to contact them.

You know technically you don't 'need' to use a sealer etc before applying a finish to raw timber. All finishes themselfs can be used as an intitial 'sealer' coat.


Cheers.



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Shane Watson..

Combine Love & Skill & You Can Expect A Masterpiece!

[Pete]

Well,
The technical service person told me it was most likely tannin staining, due to the solvents in Fungishield drawing the tannin to the surface of the timber. The only way to remove it is to wash the article with their timber reviver, an Oxalic acid solution. I'm not sure that I like the idea of washing the table with Oxalic acid and having to re-sand all of the grain that will be raised from the whole exercise. Before I rushout and follow the manufacturer's recommendation (again) does anybody have any other suggestions?

[ubeaut]

A likely story, I don't think. True the timber is pretty rich in tannin so are many other common timbers including oak and almost all australian natives.

If there was a reaction it would not be in blotches but uniform. Not only that but you can bet that Orica don't make their product tanin reactive or else they would be up for millions in law suits. The most likely answer is that they don't have a clue and the easiest way to fob you off is to blame the tannin. Well, they're hardly going to blame the product, are they?

Did you use steel wool in the sanding or cutting back process? If so this may well have set off a reaction with the Fungishield and the tannin in the wood. This would also account for the blotchiness.

I would use a very thinned down white shellac as a base/sealer, then follow it with a fine sand and pretty well any finish you like.

Never use steel wool in the sanding process. It is designsd for use with metal. Not timber.

Hope this helps a little.

Cheers - Neil http://ubb.ubeaut.com.au/ubb/smile.gif

[Shane Watson]

I just had to go get some stock, so I checked out this Fungishield. It really sounds like it was developed for external use, but that dosn't determine why it has done what it has. I tend to agree with Neil. Although a great marketing ploy for them, One product ruins the timber, so they advise another of there products to recitfy the problem...... Hmmmmmmm Somethings smelling fishy..... http://ubb.ubeaut.com.au/ubb/wink.gif

[Pete]

No steelwool was used. I started off with 180 grit paper, followed that with 240, then 400 grit.
I think that this may just go down as one of those freaks of nature. I think I'll just live with the small blotches rather than messing around any more. Next time it's no Fungishield and maybe just a shellac sealer followed by copious rubbing with Polyurethane (thinned of course).
Thanks for your help guys.
Pete
http://ubb.ubeaut.com.au/ubb/biggrin.gif

[Ashley]

It probably won't help you much, but I have used Fungishield on both Jarrah and Merbau (generally when I have been using the timber for outdoor/semi-outdoor situations)without any drama's (I live in Darwin, so it is of benefit to protect against fungal spores). I don't ever recall having a problem similar to what you are describing, but I have had 'spots' develop on the merbau when washing/drying it to leach out the tanin prior to Fungishield & coating with FW Decking Oil. After this washing process I used the FW Woodclean, and no it did not remove these tanin spots (certainly it did clean up any dirty/grimey timber quite well however. I seem to recall reading/hearing that it is also supposed to remove 'waxes and oils naturally occuring in the timber and allow better penetration of decking oils & adhesion of surface coatings.

Hopefully the above is of some benefit,

regards,

Ashley