Help with Shellac and mft3 mdf

[festal]

hello all
I decided to refinish my mft3 top.  I sanded and applied shellac.  It worked great first time but I ended up getting marks from rockler pucks i used to elevate them. So i decided to sand it lightly again and
apply shellac again.  2nd coat came out horrible so back to sanding and reapply shellac.
3rd time was better but not as good as first time. i think reason first time came out good was because most of it got absorbed by mdf.  Subsequent ones were not absorbing.
So now as you can see in the pictures i have runs and blotches.

Few upclose pictures

Any good easy way of fixing this?  maybe wipe it with DNA to dilute it and feather it out?  not sure what I can do.

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[Michael Kellough]

Shellac is great a sealer coat but I don’t like much after that as it dries so fast I can’t get it on evenly either.

 

[rvieceli]

I think frankly you might be better off sanding it down and calling it a day. You’ll probably have some protection from the coats that were absorbed.

I try to throw down a piece of the red rosin paper like this when doin glue ups on the top.
https://www.lowes.com/pd/Danco-36-in-x-167-ft-500-sq-ft-Red-Rosin-Paper-Roof-Underlayment/3395978

Ron

 

[Packard]

Shellac will dissolve shellac.  For adhesion, I find that sanding is not required.

I have successfully wiped on Sealcoat, which is already cut and ready to use.

I would try that, wiping until the shellac has become uniform looking.  At that point the Sealcoat will have dissolved and merged with the original shellac.

Sealcoat is dewaxed and water-clear.  It can be used as a sealer/primer for almost any finish.  The axiom that gets bandied about is probably true:  Shellac (dewaxed) will stick to anything and anything will stick to shellac (dewaxed only).

Also, not a factor here, shellac, when dry, is child-safe and edible.  Every M & M you have ever eaten was coated with shellac (food grade called “confectioner’s glaze” or “food glaze”.

But shellac will dissolve with alcohol, an issue if you spill alcoholic drinks on the surface.  I had a friend that preferred shellac over modern clear finishes.  If his furniture got scratched, he would dip a rag in shellac and wipe over the scratch to repair.  Repairs on acrylic involve a lot more work (but acrylic is far more durable).

 

[festal]

Shellac will dissolve shellac.  For adhesion, I find that sanding is not required.

I have successfully wiped on Sealcoat, which is already cut and ready to use.

I would try that, wiping until the shellac has become uniform looking.  At that point the Sealcoat will have dissolved and merged with the original shellac.

Sealcoat is dewaxed and water-clear.  It can be used as a sealer/primer for almost any finish.  The axiom that gets bandied about is probably true:  Shellac (dewaxed) will stick to anything and anything will stick to shellac (dewaxed only).

Also, not a factor here, shellac, when dry, is child-safe and edible.  Every M & M you have ever eaten was coated with shellac (food grade called “confectioner’s glaze” or “food glaze”.

But shellac will dissolve with alcohol, an issue if you spill alcoholic drinks on the surface.  I had a friend that preferred shellac over modern clear finishes.  If his furniture got scratched, he would dip a rag in shellac and wipe over the scratch to repair.  Repairs on acrylic involve a lot more work (but acrylic is far more durable).

Thank you. This is actually dewaxed sealcoat is what I applied

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[Packard]

Try wiping.  It is easier to control.  I use Scott “Rags”, a tougher than normal paper towel for my wipe on finishes.  I allow the towels to air dry while draped over the edge of my trash can.  Once they are dry, I toss them in the trash.

Wipe on leaves a much thinner film than brush on.  About three coats of wipe on = 1 coat of brush on.  The shellac dries so quickly that I can apply three coats in an afternoon.  An no brushes to clean.

Once I switched to wipe on, my brushes have gone on vacation.

 

[festal]

Try wiping.  It is easier to control.  I use Scott “Rags”, a tougher than normal paper towel for my wipe on finishes.  I allow the towels to air dry while draped over the edge of my trash can.  Once they are dry, I toss them in the trash.

Wipe on leaves a much thinner film than brush on.  About three coats of wipe on = 1 coat of brush on.  The shellac dries so quickly that I can apply three coats in an afternoon.  An no brushes to clean.

Once I switched to wipe on, my brushes have gone on vacation.

Thank you. Trying it now. Do you do spit treatment or one coat to entire thing?

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[Packard]

I find that the wiping process goes really fast.  You will want to do a coat of all the surface at one time.

My radial arm saw has a MDF table.  Each time I did a wiping job, I wiped the saw table with what was left on the rag.  I probably did a third of the table each time  the various coats blend so well, you could not tell that I was scavenging shellac from other jobs.  Wiping is very forgiving.

I also wipe oil based poly over water based finishes where I want the durability of poly along with color.  Only on dark colors though.  It will make light colors noticeably yellow.  And gloss or semi-gloss work well.  Satin and mat look cloudy from the dulling agents.

 

[festal]

Did one coat yesterday. A bit better

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[Packard]

The wipe on acts as bothe a coating and a solvent.  Where you need to blend the old finish with the new, apply extra and work it a bit with the rag.  It will likely dissolve the old finish enough to blend.

When you are happy with the appearance, lightly go over the surface to assure an even application of shellac.

 

[festal]

The wipe on acts as bothe a coating and a solvent.  Where you need to blend the old finish with the new, apply extra and work it a bit with the rag.  It will likely dissolve the old finish enough to blend.

When you are happy with the appearance, lightly go over the surface to assure an even application of shellac.

Thank you

 

[ElectricFeet]

Did this myself the other day. I used a shellac cut that was far too thick to start with and then I started running out, so I thinned it down … and down … and down. Was a bit of a farce towards the end  ;D

But it did the job. It was a bit grabby on the thicker parts at first, but after a few days’ use, it’s not a problem. I actually see it as a feature, rather than a bug. The less slidey, the better. 

The thinner cut came out way better. Maybe you need to add some more alcohol to yours too?

I see you’re painting it screwed down to the table. Never a good idea to paint only one side. My tip? Unscrew it, turn it over (you’ll need to take out the threaded inserts and replace them the other way up), and paint the new top (the old bottom). That way, you can use all the experience you’ve gained the first time round and you’ll reduce the chance of it cupping due to humidity only being absorbed on one side.  By the time you want to flip it over again, maybe years from now, it’ll have settled down for sure.

 

[festal]

Did this myself the other day. I used a shellac cut that was far too thick to start with and then I started running out, so I thinned it down … and down … and down. Was a bit of a farce towards the end  ;D

But it did the job. It was a bit grabby on the thicker parts at first, but after a few days’ use, it’s not a problem. I actually see it as a feature, rather than a bug. The less slidey, the better. 

The thinner cut came out way better. Maybe you need to add some more alcohol to yours too?

I see you’re painting it screwed down to the table. Never a good idea to paint only one side. My tip? Unscrew it, turn it over (you’ll need to take out the threaded inserts and replace them the other way up), and paint the new top (the old bottom). That way, you can use all the experience you’ve gained the first time round and you’ll reduce the chance of it cupping due to humidity only being absorbed on one side.  By the time you want to flip it over again, maybe years from now, it’ll have settled down for sure.

I actually did paint the bottom before.  I painted both sides when they were off the legs.  Problem was that i placed mft on the rockler pucks and black rubber squares from the pucks imprinted into the corners of the mft.  So in my half assed attempt to fix it, i started this mess lol.  All i had to do was use the triangle pyramids that came with the pucks.  No idea why i didn't use them lol.

I ended up applying few more coats of shellac and then did light sanding with maroon festool vlies and my etsc150.  came out great

 

[jaykojc]

Run your track saw across it.  Once you get a few grooves cut in there, you won't notice blotchy shellac!  That top looks way too new...