Furniture, Wood and Cabinetry Finishing - table refinishing
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larryc
05-11-03, 12:18 PM
My brother wants me to put a coat of polyurathane on a dining room table he bought at auction and the wood type is unknown(it's an oval table laid out in what looks like 4 sections. The grain is laid out in a "V" type pattern on each end). He doesn't want the look to change, just wants a more durable surface. He had been using table protectors that came with it. The grain is actually able to be felt(uneven), but the finish is very good and looks nice.
Myproblem is, do I simply wipe down with lacquer thinner and apply polyurethane, or am I going to have to do something different. I don't want to ruin the table top, so am kind of afraid to do anything. help!
Myproblem is, do I simply wipe down with lacquer thinner and apply polyurethane, or am I going to have to do something different. I don't want to ruin the table top, so am kind of afraid to do anything. help!
chfite
05-11-03, 09:09 PM
It sounds as if the veneer is delaminating. When you look across the table top, can you see ridging along the lines where the veneer sheets meet?
If this is a nice table, finding out what the finish is currently and renewing it may be the best course of action. Finishes such as lacquer, tung oil, and shellac can be renewed by adding to them.
Look on the underside of the the table for a manufacturer's identification. That may help.
If this is a nice table, finding out what the finish is currently and renewing it may be the best course of action. Finishes such as lacquer, tung oil, and shellac can be renewed by adding to them.
Look on the underside of the the table for a manufacturer's identification. That may help.
Bob I'm not
05-14-03, 02:24 PM
you can determine the finish type by doing a solvent test .
first dab on a small amount of denatured alcohol ; if the finish softens , it is shellac . most likely , this is not the case .
if the finish is not affected by the alcohol , dab on a small amount of laquer thinner ; if the finish softens , it is laquer . this is more probable . this could also point to water based finish , but highly unlikely as factories hate using it and most weekend finishers use polyurethane / varnish .
if the laq thinner has no affect , the finish is either varnish or some type of conversion finish ( as in stock from the factory ) . this is the most likely outcome .
as chfite stated , laquer and shellac can be reamalgamated . varnish , water base , and conversion finishes cannot be .
as for the grain that can be felt............ is it possible that a very heavy coat of varnish was applied over a poorly sanded surface ? it's hard to explain in writing , but this will look and feel different than delamming veneer . you will feel the pointy peeks where bad veneer is starting to buckle . in the case of a finish applied too thick , you will only feel " high points " over the grain if it is a coarse wood , but the high spots wont be pointy . know what I mean ?
as for applying poly over the existing finsh......sure it can be done . it's been done thousands of times , I'm sure . is this the best of the possible solutions ?..................... no its not .
if a solvent test points to varnish , it wont ruin whats already there . the 2 layers may not bond properly , and over time it will fail . but it kind of sounds like your brother is unhappy with it's current appearance , so maybe a cheap fix is better than none at all . you can sand the existing finish with 220 grit SANDING PAD and then apply your wipe on poly . but be advised : if your wipe on poly is not compatible with the existing finish , IT MAY FAIL IMMEDIATELY .
by the way , the best fix would be to remove the existing finish completely , and then refinish . this is assuming that the veneer is intact . if the veneer is failing................ well , thats a whole new thread;)
first dab on a small amount of denatured alcohol ; if the finish softens , it is shellac . most likely , this is not the case .
if the finish is not affected by the alcohol , dab on a small amount of laquer thinner ; if the finish softens , it is laquer . this is more probable . this could also point to water based finish , but highly unlikely as factories hate using it and most weekend finishers use polyurethane / varnish .
if the laq thinner has no affect , the finish is either varnish or some type of conversion finish ( as in stock from the factory ) . this is the most likely outcome .
as chfite stated , laquer and shellac can be reamalgamated . varnish , water base , and conversion finishes cannot be .
as for the grain that can be felt............ is it possible that a very heavy coat of varnish was applied over a poorly sanded surface ? it's hard to explain in writing , but this will look and feel different than delamming veneer . you will feel the pointy peeks where bad veneer is starting to buckle . in the case of a finish applied too thick , you will only feel " high points " over the grain if it is a coarse wood , but the high spots wont be pointy . know what I mean ?
as for applying poly over the existing finsh......sure it can be done . it's been done thousands of times , I'm sure . is this the best of the possible solutions ?..................... no its not .
if a solvent test points to varnish , it wont ruin whats already there . the 2 layers may not bond properly , and over time it will fail . but it kind of sounds like your brother is unhappy with it's current appearance , so maybe a cheap fix is better than none at all . you can sand the existing finish with 220 grit SANDING PAD and then apply your wipe on poly . but be advised : if your wipe on poly is not compatible with the existing finish , IT MAY FAIL IMMEDIATELY .
by the way , the best fix would be to remove the existing finish completely , and then refinish . this is assuming that the veneer is intact . if the veneer is failing................ well , thats a whole new thread;)