LumberJocks

Finishing with Poly (will I ever get it right?)

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by MarkShx posted 08-08-2009 06:23 PM 7101 views 2 times favorited 16 replies Add to Favorites Watch
View MarkShx's profile

MarkShx

8 posts in 2677 days


08-08-2009 06:23 PM

I am trying to finish a bar top and have had many problems. I have applied and removed more coats then I care to mention. I started brushing one product, it was too thick & gooey. Then changed to Minwax, and applied a pretty good coat but could never get a clean topcoat (bubbles and over-brushing). So I changed to Minwax wipe-on, this was ok but the finish did not have as good of a shine as brush on. So I changed back to brushing the Minwax but thinned it 15-20%. Now I am getting way too many bubbles. I am using a natural china bristle brush.

My wife thinks I am crazy but I am considering spraying it on now!

One of my problems is that the bartop is rather long and has a curved edge. Preventing drips or sagging over the edge all while trying to get a nice continuous coat on the top is rather hard. Now if you throw in a bunch of bubbles it starts to seem like an impossible task!

Lets start from scratch. Can someone tell me the proper way to brush poly including the amount to put on the brush and how to deal with bubble while you are brushing. (I tried to pop some by blowing slightly or by touching them slightly with the brush but that seems to leave wavyness especially if they aren’t handled instantly)

-- Mark, New Orleans


16 replies so far

View AaronK's profile

AaronK

1440 posts in 2928 days


#1 posted 08-08-2009 06:57 PM

i should be the last one to talk, but i guess i’ll be the first.

you mention that the minwax wipe-on had less gloss. that seems strange to me, as long as both of them are “gloss” finishes. anyway, supposedly the only part that gives the gloss is the top surface anyway, so do you think you could use the wipe on to build up the finish (seems weird, but…) and then do something special for the final top coat to give it the gloss you want?

another thing is, i thought 2-part epoxy coats were the bar-top standard? might want to look into that before investing in spray equipment/infrastructure.

View Scott Bryan's profile

Scott Bryan

27251 posts in 3286 days


#2 posted 08-08-2009 07:07 PM

Mark, it is natural for the first coat or two to have some bubbles form in it. Bubbles come about from a variety of sources- overworking the poly, brushing too fast or from the wood itself. Open grained woods like oak have air entrained within the wood itself that will show up when the top coat skims over and traps them in the finish. But in your case I do not believe that bubinga would be an open grained wood. To get rid of them simply lightly scuff sand the topcoat after it has cured and proceed with another coat.

I generally get best results using a wipe on oil base poly product. However, as the name implies this is meant to be wiped on which can be done with a pad made from clean lint free cloth or paper towel. I can apply a wipe on finish as quickly as I can spray one. The advantages of the wipe on products are that they dry quickly, are self leveling and are not prone to runs and sags. I can generally apply a second coat on in as little as 4 hours, depending on the ambient temperature. The only drawback with this type of topcoat is that wipe on products need to have more coats applied to build the finish since they are generally a 50:50 mix of poly and mineral spirits. For most of my cabinetry I generally can get by with 4 to 6 coats of wipe on gloss poly. This gives me a nice glossy sheen that protects the wood well and is water resistant.

If you want to go this route save yourself some money and simply dilute an oil base poly 50:50 with mineral spirits.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View MarkShx's profile

MarkShx

8 posts in 2677 days


#3 posted 08-08-2009 07:40 PM

Thanks Scott. How do you prep the surface between wipe-on coats?

-- Mark, New Orleans

View John Ormsby's profile

John Ormsby

1283 posts in 3201 days


#4 posted 08-08-2009 08:14 PM

I always try to spray on the final coat when using poly. I rarely use a brush to apply coats. I have found that using the applicator pads sold at the Borg stores work great. Just put some poly in a paint tray. I usually put aluminum foil in side the tray to save on trays. Then spread the poly onto the surface evenly. The edges get just a bit lighter coat in order to prevent sagging and runs. I have never had a problem with bubbles. The pads are the small ones that are white and green. About 3” x 5” . Make sure you let the ply dry thoroughly between coats before sanding. I will also spray a couple of wet on wet coats at the end. This works very well.
Good Luck, John

-- Oldworld, Fair Oaks, Ca

View grizzman's profile

grizzman

7798 posts in 2767 days


#5 posted 08-08-2009 09:14 PM

hi mark..sorry your having troubles, ive used the minwax poly for many years now…i use a good quality brush to start…make sure the poly has not been shaken, use a stir stick to make sure its mixed…then brush it on with good but thin coats, brush in one direction , with the grain of coarse and let it dry well..sand between each coat , i use at least a 220 grit..then i wipe with a lint free rag with paint thiner, in one direction , ive had great succses with it …very smooth …you want low humidity..and a warm room..i pretty much do a 4 coat topping for all of my tops …good luck..if you spray make sure you keep your hand in motion and same thing light coats with sanding in between…..

-- GRIZZMAN ...[''''']

View teenagewoodworker's profile

teenagewoodworker

2727 posts in 3232 days


#6 posted 08-08-2009 09:42 PM

i personally am not a fan of minwax. i like a good quality poly like general finishes arm-r-seal or waterlox. when you rub it on the coats are going to be thin so you are not going to start to get a shine for a few coats. in all you should get at least 5 coats. rubbing poly is a better idea than brushing it generally. easier and poly is designed to go on in thin coats and the brush will generally leave it to thick. so even if you apply it with a brush if should be wiped back with a cloth.

another note dont spray poly. its just not a good idea. oil baseds just arent designed to spray and dont spray well and its rough and takes forever and its just not a good idea.

View Scott Bryan's profile

Scott Bryan

27251 posts in 3286 days


#7 posted 08-09-2009 04:40 AM

Mark, in between coats I lightly scuff sand with 320 grit. I only sand enough to knock down any dust nibs that may have gotten into the finish and to generate some very light scratches on the surface of the poly. Wipe the dust off before applying the next coat. Poly bonds to the previous layer by mechanical adhesion so it needs a “roughened” surface to bond to.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View AeroClassics's profile

AeroClassics

15 posts in 2831 days


#8 posted 08-09-2009 08:46 AM

Throw the poly away! (Or dispose of it in an environmentally friendly fashion!) In any case get rid of it. I cannot think of any reason to encase something in plastic! AaronK is correct, two part epoxies such as System3 Mirror Coat are the preferred finish for a bar top. Certainly a commercial bar top. For a home bar I would suggest Behlen’s Rock Hard Table Top Finish, Arm-R-Seal or Waterlox. For the record NONE of these is a poly. Poly is the common vernacular for polyurethane. These products are varnishes. Urethane varnishes. Behlen’s and Arm-R-Seal are alkyd varnishes. Very hard and excellent resistance to household wear and tear. Waterlox is a phenolic varnish and is very tough and also flexible. Flexibility is a useful trait in a varnish.

The real beauty of varnishes are twofold: 1) They are tough and stand up to household chemicals, water and alcohol (both the drinking and non-drinking types); 2) They are almost goof proof which means for the average woodworker they are easy to apply and almost cannot be screwed up.

If there is a downside it would be the drying time, 8 hours to recoat generally and the slower build up as compared to other finishes.

So if you do not want to try epoxy then I would suggest you move to varnishes. I think you will be pleased at how easy they are to work with and how beautiful they leave your project.

Doug

-- Doug, Carrollton, TX. www.djswoodworks.com

View moshel's profile

moshel

865 posts in 3148 days


#9 posted 08-09-2009 09:21 AM

I had the same problems that you are having, and I spent my days in dark despair….
I was saved by the wood whisperer finishing DVD. its clear, its simple, it works.

Bottom line – Poly diluted 50:50 with terps, wipe on with clean cloth, sand first layer with p180 when really dry. next layers 240, 320 and then wet sand (with water when dry!) with 400 and 600 (each grit is a layer). mirror like finish…
see http://lumberjocks.com/projects/12048 for an example of this finish. I am not an expert by any means, but I progressed from being very sad to having really good and shiny finish.

-- The woods are lovely, dark and deep, but I have promises to keep...

View Kindlingmaker's profile

Kindlingmaker

2656 posts in 2990 days


#10 posted 08-10-2009 04:02 AM

Wipe on, wipe off, dry one day, wipe on, wipe off, dry one day, etc. until you build up the layers you want with your poly. It is a fact that you do have to wait a day for each coat to get good and hard before sanding with 320 or 400 grit and reapplying the next coat but it is all worth the waiting… I use Johnson’s wax after the last coat and a week of drying and another sand with 400 grit. my 2 cents…

-- Never board, always knotty, lots of growth rings

View MarkShx's profile

MarkShx

8 posts in 2677 days


#11 posted 08-11-2009 02:31 AM

Well guys… I wiped on a coat. I got a little 3×5 sponge with a soft cloth exterior. I thinned my poly 50/50 with naptha, stirred it up and poured it into a new paint tray. I wiped in one direction stopping to reload the sponge half a dozen times. All went ok BUT… The surface of the bar where I had to stop and restart the wiping now has a visible ridge. Keep in mind that it is a long bar. There must be a better technique. I can’t wipe it in 10-12 foot swipes!

-- Mark, New Orleans

View moshel's profile

moshel

865 posts in 3148 days


#12 posted 08-11-2009 03:31 AM

don’t use a sponge. use old cotton t-shirt folded. it release the poly in a more consistent manner.
another trick to prevent ridges is to start about 30 cm into the unpainted area, go the wrong way and then the right way. this will even the ridge (I think this was also from the wood whisperer DVD). anyway, if after the sanding you can’t see the ridge – its ok. you can make the last layers even more diluted.

-- The woods are lovely, dark and deep, but I have promises to keep...

View MarkShx's profile

MarkShx

8 posts in 2677 days


#13 posted 08-11-2009 04:02 AM

Great tip! Now let me go sand off those ridges!

-- Mark, New Orleans

View teenagewoodworker's profile

teenagewoodworker

2727 posts in 3232 days


#14 posted 08-11-2009 04:18 AM

also poly or varnishes have a long working time. you dont want to just wipe it on and leave it. thats why you really shouldnt thin it so it dries so fast. just to clear it up its only dried not cured once the solvent leaves. any and all oil based products are made to be flooded on the surface and wiped off. not to just be wiped on and left. like moshel said use a folded t shirt or another cotton rag… lint free of course.

View ND2ELK's profile

ND2ELK

13495 posts in 3238 days


#15 posted 08-11-2009 05:19 AM

Polyurethane is all I ever have used on all my cabinets. After staining the cabinet and letting it dry I would brush on a coat of polyurethane. When dry I would steel wool with 000 steel wool and vacuum off. Then I would brush on the second coat of polyurethane. After it dried I would wax the cabinets and compoent parts using 000 steel wool to apply the wax. I have never had any problems using polurethane.

God Bless
tom

-- Mc Bridge Cabinets, Iowa

showing 1 through 15 of 16 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com