Wipe on poly issue/question

[Matt Uchida]

I decided to add a satin wipe on poly finish to my monkey pod dining table due to having babies that spill and whatnot. Prior to that it only had multiple layers of danish oil, which also left a dull coat when I wanted a little bit more of a sheen. (It is end grain) So I sanded it with a random orbit sander with 220 or 320 grit disk lightly and cleaned off the dust.
This original project can be seen here.
http://www.sawmillcreek.org/showthre...d-dining-table.

The first layer went down nice and smooth. I came back maybe 14 hours later and it was slightly tacky. I live in HAwaii and in an area that rains a fair amount so we have high humdity and this was being done in doors. So i figured that since it has been a half a day and the can says 2-3 hour dry time I would be safe. I also had a fan pointing at it for like 5 hours. Windows were open of course.

Well I put the oil on a rag just like I have always done and tried to spread it around but it resisted. It went from spreading a wonderfully glassy smooth product to spreading honey. It was streaky and the rag would slip out of my hands. I again let that fry for about 10 hours or so but it was still tacky and I tried again, same results. The wipe on poly did not want to spready nice and glassy but it felt very sticky when trying to glide the rang over the surface.

The product hasn't gone bad because I have been using it recently like this week without this problem.
Would a porous end grain affect how the poly urethane dries or cures?
Is my problem simply from not letting it dry all the way before putting on another coat? I am guessing my mistake was in trying to apply a new coat when it was still slightly tacky.
Do you think humidity and indoor conditions are to blame for the overly long dry times?
Should I just buy a spray can of poly urethane so i get an easy smooth coat with a satin sheen on top of the existing 3 coats and call it a day?

I wanted to finish this before my wife and kid comes home 12 hours from now so that they don't have be around the smell. I guess I wont be able to finish it because as this last coat was drying 10 mins after it applied the finish was still dull and a little bit streaky so while it might have a seal to it it is not a nice satin finish yet.

[Howard Acheson]

I am not familiar with monkey pod wood so I don't know if there are known specific finishing issues. But, from you description of the reaction of the wiping varnish, it sounds like in could be some sort of incompatibility of the finish with the oils in the wood. This type of incompatibility is quite common with tropical woods. Another issue could be the oil/varnish finish you had previously applied. If you have applied the oil/varnish a number of times, it may never have fully cured when it soaked into the end wood. The usual "fix" for both of these problems is to first remove all the finish with a chemical paint stripper containing methylene chloride. Then create a barrier coat between by applying a coat of dewaxed shellac. Then apply your oil based varnish or poly varnish finish.

[Matt Uchida]

I am not familiar with monkey pod wood so I don't know if there are known specific finishing issues. But, from you description of the reaction of the wiping varnish, it sounds like in could be some sort of incompatibility of the finish with the oils in the wood. This type of incompatibility is quite common with tropical woods. Another issue could be the oil/varnish finish you had previously applied. If you have applied the oil/varnish a number of times, it may never have fully cured when it soaked into the end wood. The usual "fix" for both of these problems is to first remove all the finish with a chemical paint stripper containing methylene chloride. Then create a barrier coat between by applying a coat of dewaxed shellac. Then apply your oil based varnish or poly varnish finish.

I have used the poly on top of danish oil before and not had the problem, plus this table had been treated with the danish oil about a year ago so for sure it has cured. Actually now that I think about it i did put a thin layer of gunstock oil but I am not sure if I put it on both tables. (I made two identical and recoating them both)
So I kind of doubt it is a compatability issue. The danish oil can says you you can cover it with polyurethane and i have covered danish oil with polyurethane before.

I could try paint on for the final coat but it always seems to leave streaks when I do it or bubbles maybe.

I don't know if monkey pod is oily or not but i suppose it could be the problem. I am checking the tables now after a full 24 hours and they are not tacky but don't feel like the poly has cured fully, maybe not as hard as I would have thought? I am thinking about trying to put another coat of wipe on poly in the morning so that will be about 36 hour dry time or so and see if it goes on all nice and smooth again. I did read another thread where people wiped on some sort of naptha? or other mineral spirit on top of sticky polyurethane and it helped it dry/cure. I don't have any of these but I can try that if it doesn't work cure right.

[Matt Uchida]

Well I bought naptha and wiped the table down twice and put on a new coat of wipe on poly urethane. It doesn't seem very tacky now almost 18 hours later but just very slightly tacky perhaps. On some parts the naptha seems to have taken off all of the polyurethane so even after the new coat it isn't even yet. Also this most recent coat still came out a little streaky.

I went out and bought some zinser no wax shellac and am going to wipe down the table a few more times with naptha and seal it with the shellac then try some polyurethane on it. I will report how that comes out.

Two questions, any experience with shellac? It seems somewhat thin but the can says use a brush.
Second I was thinking about thinning the poly urethane just a tad since it was still a little streaky. I am down to the last 1/4th of the can so I am wondering if maybe it thickened a little after using it on various projects.

[Scott Holmes]

First time user with shellac; I suggest a pad and a quick and I mean QUICK wipe like the kid wipes the table at the fast food place. Don't overlap and do 2 quick wipes about 20 mins apart.

Better and easier is to buy a can of spray shellac.. It's de-waxed and it will be even easier.

Light coat is all you need.

[Matt Uchida]

What do you mean by pad? How about old shirt/underwear cloth? 20 minutes is long enough to put on a second layer? Would a little longer be ok since I am in a humid environment?

Thanks

[Howard Acheson]

Wiping down with naphtha or other paint thinner like mineral spirits is NOT the thing to do. It will not help in drying out the finish. That technique is only used when an oil based stain is not drying properly.

At this point, shellac whether brushed on or wiped on, is not something to do either. You should not apply any thinners or other finishes unless the surface you are coating is fully dried. Give the item 4-5 days with a fan gently blowing over the surface and see if it dries. Once dried, it should be scuff sanded with 220 paper, vacuumed and a coat of oil based poly applied. If it doesn't dry you will have to use a chemical stripper containing methylene chloride and start over.

BTW, poly is not really a hard finish. In fact it's quite soft. It takes 4-7 days to begin to feel "hard" and 3-4 weeks to cure and become as "hard" as it can.

[robert raess]

I live in AZ.,and have applied urethane on wood floors over many years.They all dry in 7-12 hrs.A few notable exceptions were:1.sanding and coating southern yellow pine, that smelled like turpentine and filled up my sandpaper with resin.I came in 24 hrs. later and it had not dried,and gave it another day and it was dry.#2. working in wisconsin my dry times were longer than here in az.#3.I used McCloskey Gym seal[good product and all that] but i was just starting out..and it took a long time to dry..and now i use other urethanes.
I have seen the alcohol in shellac wrinkle poly. esp. if not cured.Some poly's cure faster than others[that comes with exp.].Two things that have helped speed things up are :Japan drier and Naptha,i have even used those successfully mixed together.Re. wiping polys,Fine woodworking[i believe] rated Minwax WOP as one of the better ones, and before that Hopes was one of my fav.'s.Poly's, can take 24-72 hrs. to dry and 30days to fully cure. Hope this helps. Rob

[Barry Richardson]

I had this problem when living in San Diego by the beach and there was high humidity. I'm guessing your entire problem is humidity related, as mine was. The first coat of poly on raw wood usually dries normally, but each successive coat will take longer to dry. You've just got to be patient. I've used thinner like you, to clean up when I had these problems and it worked fine for me, contrary to what Howie said.
Different Subject: Question for Howie. I always understood that Poly was a hard finish. If it's not, what is a hard finish?

[Matt Uchida]

Wiping down with naphtha or other paint thinner like mineral spirits is NOT the thing to do. It will not help in drying out the finish. That technique is only used when an oil based stain is not drying properly.

At this point, shellac whether brushed on or wiped on, is not something to do either. You should not apply any thinners or other finishes unless the surface you are coating is fully dried. Give the item 4-5 days with a fan gently blowing over the surface and see if it dries. Once dried, it should be scuff sanded with 220 paper, vacuumed and a coat of oil based poly applied. If it doesn't dry you will have to use a chemical stripper containing methylene chloride and start over.

BTW, poly is not really a hard finish. In fact it's quite soft. It takes 4-7 days to begin to feel "hard" and 3-4 weeks to cure and become as "hard" as it can.

Thanks for the reply. What you said appears contradictory to a lot of other advice I read on here, maybe I need some clarification.

When reading the can of shellac it says dewaxed shellac can be used as an undercoat for polyurethane.
Will the stripper remove the danish oil because I don't want it to do that, I am guessing it won't go into the wood though.
It was my understanding that poly is the best finish for something that will get higher use with water and food, without going to that thick stuff they pour on wood at bars that make it look plasticky of course.

EDIT: i just tried the dewaxed shellac on a small test space and it is clear that the polyurethane needs to be stripped off first. I didn't realize the shellac is so thin and it does nothing to blend the line between where some poly remains and where the naptha pulled off all of the poly. I may have to do this indoors and it sounds like the strippers are pretty bad stuff though. I live in a condo. I could take the random orbit sander to the couple of layers of poly that are on the table. It is 3 inches thick of solid wood so I am not going to be worried about too much wood lost, plus I think the danish oil went pretty deep in the wood since it is end grain.
Thoughts?

BTW is all shellac as thin as the zinser sealer coat or is that thinned shellac? I can't imagine using it to build up layers.

I have used the danish oil, and poly urethane many times on poplar in the same environment and never had issues with the dry time so I can't help but think it must be a problem with the wood itself and not the environment.

Since Naptha did apparently help to dry out the poly or at least made it not sticky I am wondering if i could jsut sand the existing poly off since it has streaks in it and then naptha between each coat of poly.

Or should i try something else all together like waterlox or that Behlen's rockhard? I don't want a plasticky thick look but it needs to be durable and water resistant because of one1year old and another on the way. I have heard the waterlox is not very water resistant (raised grain when a cold glass was left on the table)

[Harvey Pascoe]

Different Subject: Question for Howie. I always understood that Poly was a hard finish. If it's not, what is a hard finish?

All varnishes except spar cure to the same approximate hardness. A product like Minwax poly which is designed for floors cures very fast and reaches its hardness much faster than a typical alkyd. I judge this by how soon a varnish can be wet sanded and polished. For most polys its 1-2 weeks, but for alkyd its 4-5 weeks.

High humidity retards varnish drying at temps below 80 degrees. What many people don't realize is that dewpoint can really mess up a varnish finish. Before varnishing in the morning or late afternoon you should check what the dewpoint temperature is. If you close to that you need to wait until the temp comes up if you have an open shop or spray booth.

[Scott Holmes]

Howie makes a good point. I failed to tell you that the shellac can be used as a barrier coat ONCE the surface is dry. Appling a fresh coat of anything to a tacky surface is asking for trouble.

[Matt Uchida]

The surface seems dry now, probably not fully cured but dry. So I am either at the point of sanding it all off then shellac then poly OR shellac everything and hope that the poly can cover up the old streak marks and the areas where there is poly vs the areas that the poly got wiped off by the naptha.

[Matt Uchida]

Well I finished the tables but am a little disappointed, I learned a lot but my wife just wanted it done rather than be perfect. I put on 6-8 layers of zinser seal dewaxed shellac... mistake, 2 or 3 would have been good. They built up and were not smooth. The sealer did allow the wipe on poly to dry well. The wipe on poly I found doesn't necessarily work better when thinned more. It is thinner but it also dries faster and seemed to leave streaks. The sanding inbetween certain coats did not come out right and I can see scratches in the coat.
But I learned a lot so when my kids bang through this stuff in 5-10 years I will sand it off and re-coat nice and new.

I have noticed a problem. Maybe about a month after finishing I noticed the finish rubbing off on my computer table on the portion where you sit and I cannot figure it out. My wife has a condition where she sweats a a bit from her hands and I am wondering if this extra sweat or unique sweat could have eaten through 4-5 layers of wipe on poly. The portion is right where one might rest their wrists when typing on thekeyboard.
Thoughts?