problem with french polish

[astrid]

Hi,
I am new to using forums so please be patient
i have a small homebased restoration business and do my best to rescue working class antiques.
although i am self taught i an not a "cowboy" and try to only use traditional materials and methods.
now having got that out of the way to my problem.
a year or so ago I fp a piece of walnut furniture for a client,
the timber was stripped right back and properly neutlalised and prepared.
a few weeks after delivery the client said the iten was blistering.
I re did it
same thing happened
the client assures me that she is not useng anything odd to dust it and is not putting it in the sun.
I read on a website a while back that this can be caused by bacteria or fungus in the timber but cant find the reference again.
has anyone else heard of this and if so what can i do?

Thanks

[ubeaut]

Hi Astrid - Welcome to the forums.

Firstly......... Never trust a client or what they say they haven't done.

If you really want to get to the crux of the problem I need a bit of info. Heres a few quick questions that may give us an idea as to the problem.

Did you notice if the blistering was in the same place as the last time?

Did you French polish with a rubber and use oil as a lubricant?

What oil did you use(if any)?

Did you properly remove all traces of the oil from the polish?

Did you just apply a heap of coat of shellac to the work with a brush?

Did you wax the surface as a final thing or use any other preparation on the final surface?

Did you sand before applying further coats of shellac?

If so what grade and type of abrasive and did you use a lubricant like soapy water or turpentine to aid in the sanding.

Was the polishing done inside or outside?

Was there anyone using welding equipment within 300 meters when you were polishing.

How fresh was the shellac?

Did you mix it yourself or buy it premixed?

If premixed did it have a use by date in it or was it from a shop that has a really high turnover of shellac.

Did you use pure alcohol with the shellcs or was it just a cheap brand with no marking saying either Industrial Methylated Spirits (100%IMS) or 95%IMS.

There's a number of more questions I could ask to try and get to the bottom of this but this'll do for a starter.

Cheers - Neil

[MacS]

Could you better explain your definition of "blistering".

Can you take a few photos and attach them to the forum.

Do the "blisters" look like they are burnt, scalded, are there seperations in the defects, are the defects similar in shapes and sizes or different, can you tell us if the "blisters" are hard, if you press down on one does any fluid come out.

Could they be broken bubbles?

[astrid]

Hi Astrid - Welcome to the forums.

Firstly......... Never trust a client or what they say they haven't done.

If you really want to get to the crux of the problem I need a bit of info. Heres a few quick questions that may give us an idea as to the problem.

Did you notice if the blistering was in the same place as the last time?

Did you French polish with a rubber and use oil as a lubricant?

What oil did you use(if any)?

Did you properly remove all traces of the oil from the polish?

Did you just apply a heap of coat of shellac to the work with a brush?

Did you wax the surface as a final thing or use any other preparation on the final surface?

Did you sand before applying further coats of shellac?

If so what grade and type of abrasive and did you use a lubricant like soapy water or turpentine to aid in the sanding.

Was the polishing done inside or outside?

Was there anyone using welding equipment within 300 meters when you were polishing.

How fresh was the shellac?

Did you mix it yourself or buy it premixed?

If premixed did it have a use by date in it or was it from a shop that has a really high turnover of shellac.

Did you use pure alcohol with the shellcs or was it just a cheap brand with no marking saying either Industrial Methylated Spirits (100%IMS) or 95%IMS.

There's a number of more questions I could ask to try and get to the bottom of this but this'll do for a starter.

Cheers - Neil

[astrid]

HI NEIL
THANKS FOR YOUR REPLY
BLISTERING WAS IN SAME AREA
i USED A RUBBER NO LUBRICANT ( IONLY USE LINSEED IF THE WAETHER IS A BIT WARM)
BRUSHED ON FIRST 2 COATS (THIN MILK CONSISTANCY)
USED LIBERON NEUTRAL WAX SPARINGLY FINAL COAT
I mix my own shellac with pure meths and use good quality flakes well strained
shellac was fresh
i rubbed back between with high grade 400 grit paper ( that blue stuff from switzerland)
polished inside
no one was weilding
I can't think of any contaminant
this idea of a dorminant bacteria would make sense if it starts growing under the shellac after 3-4 weeks but it this is the problem what will kill it and not cause further problems?

thanks
astrid

[munruben]

the timber was stripped right back and properly neutlalised and prepared.

Might help if we knew what procedures you used to achieve this. Did you use a chemical to strip the timber.? and what did you use to neutralize it with and what preparation treatment are we talking here. Could be some kind of chemical reaction.

[astrid]

thanks john,

used meths to strip completly clean then fine sanded. let dry overnight.

astrid

[ubeaut]

Sounds very much like a contaminant of some sort in the timber, but not necessarily. Fungishield (feast Watson) should kill a fungus but I doubt very much that it's a fungus as that is usually something to affect only new timber. If it was a fungus it would have affected the original polish which you stripped.

I would be stripping the surface with a good quality paint stripper not caustic but the stuff that burns your skin if you come in contact with it. Wash it down really well with metho (no steel wool) sand until only sanding dust clogs the grit, then sand some more.

It is possible that it had been polished with MR Sheen or some other silicon containing rubbish over the years prior to your work and if the surface was crazed or cracked some of the silicon may have gone through into the timber.

If this is the case It should show when you apply the shellac, however shellac has the ability to stick to almost anything and might not show. Soak the top with cold water and see if there are any sections that try to expel the water and if so are they in the same place as the blistering. If they there is most likely a contaminant, probably silicon, but who knows. If silicon you should be able to fix it with a silicon wash.

I'm a cynical bugger and would like to see a pic of the damage as I still don't trust what clients tell me they didn't do.. The marks being in the same place seem to indicate one of 2 things. No 1 as above.... No 2 the client has put the same thing on the surface. Vase, pot plant, , tray, ornament or similar. or left it in the same place that gets concentrated beams of sunlight maybe through a leadlight window or some other heat source like a revere cycle AC or it's sitting over a haet duct, etc But again, who knows. Sorry I really am a bit cynical and like to cover all possible bases before blaming the tools.

The next lot is just the musings of a silly old bugger.
I manufacture one of the best waxes available for French Polished surfaces. However my recommendation for a French polished surface is to put nothing on it at all. I particularly don't like to see any wax etc on a surface for at least a few months. Not saying that's the problem. Just wondering why you'd put the wax on the top of a freshly French polished surface.

Just reread your reply. The 400 grit abrasive you're using is it silicon carbide, and what brand and is it worn or new? Nah.... doesn't matter the blistering is in the same place - rule out the abrasive. Although I'd be using a really good 600, 800 or even 1200 wet & dry rather than 400. It isn't paint so you don't need to rough it up to key the following coats to, also a lot less scratching to get out of the surface with following applications. Try using Paraffin oil instead of linseed, you can use it all year round and it won't scum or dry out.

Sorry..... Not trying to tell you how to suck eggs, just a few hints that might help.

Cheers - Neil

[munruben]

The marks being in the same place seem to indicate one of 2 things. No 1 as above.... No 2 the client has put the same thing on the surface. Vase, pot plant, , tray, ornament or similar. or left it in the same place that gets concentrated beams of sunlight maybe through a leadlight window or some other heat source like a revere cycle AC or it's sitting over a haet duct, etc.

I think you might be on the right track here Neil. Actually this is very likely, people have a habit of putting things in the exact same spot every time. I would even consider taking a trip to the said customer and see exactly where the piece of furniture has been standing and find out what has been placed on it. I remember we had an oak table way back in the 50s in the UK and there was 4 of us in the family and after a while you could see the 4 round rings of the hot plates that had been placed on the table where each member of the family sat, even though we always used a table cloth.

[astrid]

Thanks guys, I really appreciate this,
the sillicone idea is a possiability, were talking about the back of a maple (sorry I think i said walnut) bergier sofa so it wont have had things put on it,
however the original polish was completly worn in patches so her (or her cleaner) may have been using Mr sheen on nearly raw timber. I helped place the furniture and she is keeping it in a corner out of the sun but the house suffers from rising damp.
I did sand down pretty hard the second time round and the blistering is not so bad this time.
I think I'll hit it with both barrels this time for fungus and silicone and see what happens,
Ill also keep it under observation at my place for a few months and see what happens.
unfortunatly my workshop is too small to keep it there.

thanks enormously
astrid
PS dont like icons
but I really mean thanks, this has been driving me nuts

[astrid]

John and neil

By the way I totally agree that wax on a full fp is a waste of time but I am talking about 3-4 brush coates rubbed down with a rubber 2-3 times.
I find a good light wax gives a mellow burn without the glosyness of a full polish,
as I said I work in the working class antique area not haut antiques,
I know my limitions.

talk soon
astrid

[MacS]

Fisheyes and Blistering are 2 different problems, and would not look the same.

Fisheyes, are circular craters in the coating, whereas, blistering could look like the coating was scalded, burned, or it may appears as small pimples in cluster sometimes they maybe broken.

In most cases a few photos would be better then verbal explanations.

Could you post a couple.

MacS

http://www.macsimmons.com/

http://iswonline.com/OnlineFeatures/...of%20Finishing

[astrid]

I'm a bit of a trog when it comes to photo,s but I think we're on the right track with the silicone or mould idea, the blemishes are more like somthing is coming from under rather from an external influence but thanks for the imput
astrid

[Sebastiaan56]

Hi Astrid,

Moulds need specific conditions to grow. They are different for each group of moulds. If there was a localised drying or wetting they may happen. On older timber it would be throught the timber and would have damaged the structure in some way eg the surface would be powdery, or slimy to touch. If the piece has lived in a protected area it would show some kind of structural damage, broken bits etc.

Ethanol (Industrial meths) will kill off 90% of moulds. There will be spores, but trapped under the finish I dont see how they could propogate. I suspect Neil has hit it on the head with Silicones (Dimethylpolysiloxane). Best wetting agents on the planet. Ethanol will not shift silicones, sanding will eventually.

Im not much at finishing but I have 10yrs direct microbiology behind me. Dont ask how I found out so much about silicones, but if there was one group of chemicals I could get rid of....

[astrid]

Hi sebastiaan
thanks for this, i think you are probably right i just remembered a posting on another site about bacteria or mould.
maybe that posters timber was damp or somthing.
I did sand back pretty hard the second time but as i said the original finish was pretty worn and may have been mr sheened for years.
ill just have to sand harder.

astrid