smooth finish on rough wood? - Page 2 - Woodworking Talk - Woodworkers Forum
 1Likes
Reply
 
Thread Tools Display Modes
post #21 of 34 Old 11-15-2017, 06:25 PM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
Quote:
Originally Posted by desertsp View Post
Thanks Steve. It's great to be able to get such quick feedback!

That's a good point that oak usually has a grain texture and it might look strange without. I just had my wife go and look at the table and she thinks it's fine as-is...but I'm so tempted to try the AquaCoat clear filler!

Do you think there's any significant benefit (or risk) to the AquaCoat filler versus just more coats of poly sanded back between coats, in terms of achieving a smoother surface within the next two days? (the final coat of poly has to go on by Friday evening)
I've never used the AquaCoat so I don't have any experience with it. I have a hunch if you were going to use it that it should have gone on before the poly. I would find out from the manufacturer if it can be used over poly before doing that. You could create a problem that would lead to chemically stripping the finish off.

I normally use an oil based grain filler and it is used first before any stain or anything.
Steve Neul is offline  
Sponsored Links
Advertisement
 
post #22 of 34 Old 11-15-2017, 11:34 PM Thread Starter
Senior Member
 
Join Date: Apr 2016
Posts: 113
View desertsp's Photo Album My Photos
Whelp I went ahead and added the grain filler. It?s like nothing I?ve ever used before (which doesn?t say much!). Basically it?s a thick gooey paste the texture of a heavy machine grease, which goes on bluish white and turns clear. Suspiciously like an ultra-thickened polyurethane finish, I wonder if it?s a similar chemistry?

It does shrink somewhat, as evidenced by crackling in the deeper areas filled, like >1/4? diameter nail holes that I hadn?t totally filled to the brim with epoxy in an earlier step. This AquaCoat filler probably shrunk by 10-20% in volume as it hardened in those areas and the crazing resulted. Oh well...I really don?t think anyone will notice!

The call to the manufacturer didn?t go through (I think it?s my phone, hopefully) but I found a lot of online reviews suggesting it will work over polyurethane. The manufactures instructions don?t warn against that, either.

Fingers crossed but I think it?ll work out and be ready by Saturday!
desertsp is offline  
post #23 of 34 Old 11-16-2017, 08:05 AM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
It doesn't sound good. The product was intended to use on smooth surfaces and just fill grain. I don't know what to think about allowing it to puddle. It may be if you allow it to dry very well and sand the crazing off it might be alright, I just don't know. At this point it really doesn't matter, it will either work or it won't. Might as well go with it and if it lifts strip it off next summer and do it over.

When I use an oil based grain filler it's thinned to about the consistence of mayonnaise. You brush or spray it on and let it thicken to a paste. Then with a coarse cloth it is rubbed into the grain removing all the excess. Only the grain retains the grain filler. Then it's allowed to dry and lightly sanded and stained before applying the finish.
Steve Neul is offline  
Sponsored Links
Advertisement
 
post #24 of 34 Old 11-16-2017, 10:47 AM Thread Starter
Senior Member
 
Join Date: Apr 2016
Posts: 113
View desertsp's Photo Album My Photos
Quote:
Originally Posted by Steve Neul View Post
It doesn't sound good. The product was intended to use on smooth surfaces and just fill grain. I don't know what to think about allowing it to puddle. It may be if you allow it to dry very well and sand the crazing off it might be alright, I just don't know. At this point it really doesn't matter, it will either work or it won't. Might as well go with it and if it lifts strip it off next summer and do it over.

When I use an oil based grain filler it's thinned to about the consistence of mayonnaise. You brush or spray it on and let it thicken to a paste. Then with a coarse cloth it is rubbed into the grain removing all the excess. Only the grain retains the grain filler. Then it's allowed to dry and lightly sanded and stained before applying the finish.
I think you're definitely right to be concerned about the crazing. Fortunately it's only in a few small areas (nail holes) and I was able to Dremel it out and replace with black epoxy, which I should've done in the first place. If this weren't a rustic style table it would have been a deal breaker!

The product did serve its intended purpose of filling the grain, and the table is now smooth enough to wipe clean even for something like peanut butter or soup. I think it would have required at least four more coats of polyurethane to do that. So I'm going to call it a success, but will be observant of future issues.

Next time I'll follow your protocol of filling grain BEFORE finishing instead of as an afterthought.
desertsp is offline  
post #25 of 34 Old 11-16-2017, 11:02 AM Thread Starter
Senior Member
 
Join Date: Apr 2016
Posts: 113
View desertsp's Photo Album My Photos
Here's what happens with the AquaCoat Clear Wood Grain Filler if you get it into a deeper recession. That's a divot about 5mm wide and 2-3mm deep. This is 8 hours after application and the material feels hard and dry, however it stayed white and cracked.

Not judging the product...this is user error.
Attached Images
 
desertsp is offline  
post #26 of 34 Old 11-16-2017, 11:23 AM
Senior Member
 
Join Date: Mar 2016
Location: Fresno, CA
Posts: 265
View mackman's Photo Album My Photos
Just in case you ever use it again: If you ever do use it before finishing, you need to make sure to sand down to bare wood afterwards. Otherwise, as I said before, it'll interfere with the finish absorbing into the wood and result in an ugly, uneven finish. Definitely not something you could have done on an uneven surface like the one you started with here.
mackman is online now  
post #27 of 34 Old 11-16-2017, 11:27 AM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
If you are going to use the Aquacoat again you better study up on it. Since it is clear I bet it would seal the wood like a glue stain and then you wouldn't be able to stain it. It might be you need to stain the wood first, use the Aquacoat and then the finish.
Steve Neul is offline  
post #28 of 34 Old 04-07-2018, 12:47 PM
Senior Member
 
Join Date: Mar 2016
Location: Fresno, CA
Posts: 265
View mackman's Photo Album My Photos
Quote:
Originally Posted by Steve Neul View Post
No, don't do that. Poly will dry on the surface and stay wet underneath for months. It's different with epoxy. Once mixed with hardener you could pour it into a jar to the top and put a lid on it and put it in a vacuum chamber completely free of air and it would harden all the way to the bottom in a matter of hours.

I believe I misunderstood the objective with the finish. I though you were trying to get the surface just smooth enough to be able to keep it clean. If you are trying to completely level the surface then epoxy is the only answer. It may have a plastic look to it but so would polyurethane. You could brush a few hundred coats of poly on letting it dry completely between coats but poly isn't elastic enough to deal with wood movement. The first time the wood expands or contracts poly would crack. It's just too hard for that application.
Sorry for the thread necro, but I'm working on a very similar project now and the client wants a completely smooth top over rough-cut oak. I suggested epoxy, but since it's a four-foot-wide table, I wondered how well epoxy generally handles that kind of potential movement. Some internet sources suggest that epoxy is terrible with wood movement, and others suggest it's just fine. But here, you seem to say that epoxy is actually better with wood movement than standard polyurethane would be? Could you let me know your thoughts? (it wouldn't be a terribly thick layer: Just thick enough to fill in the saw marks and level the surface).
mackman is online now  
post #29 of 34 Old 04-07-2018, 05:39 PM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
Quote:
Originally Posted by mackman View Post
Sorry for the thread necro, but I'm working on a very similar project now and the client wants a completely smooth top over rough-cut oak. I suggested epoxy, but since it's a four-foot-wide table, I wondered how well epoxy generally handles that kind of potential movement. Some internet sources suggest that epoxy is terrible with wood movement, and others suggest it's just fine. But here, you seem to say that epoxy is actually better with wood movement than standard polyurethane would be? Could you let me know your thoughts? (it wouldn't be a terribly thick layer: Just thick enough to fill in the saw marks and level the surface).
A finish thicker than a lawn and leaf trash bag is considered a thick finish. Any thick finish whether it is epoxy or polyurethane can be trouble with wood movement. What it comes down to mostly is the moisture content of the wood when you do a thick finish and if you also seal the underneath side. If the wood moves very much the finish has the tendency of cracking. The wood needs to be very dry.
Steve Neul is offline  
post #30 of 34 Old 04-07-2018, 05:46 PM
Senior Member
 
Join Date: Mar 2016
Location: Fresno, CA
Posts: 265
View mackman's Photo Album My Photos
Quote:
Originally Posted by Steve Neul View Post
A finish thicker than a lawn and leaf trash bag is considered a thick finish. Any thick finish whether it is epoxy or polyurethane can be trouble with wood movement. What it comes down to mostly is the moisture content of the wood when you do a thick finish and if you also seal the underneath side. If the wood moves very much the finish has the tendency of cracking. The wood needs to be very dry.
According to my moisture meter, the MC of the oak is right around 8.5%. It'll be kept indoors in the California central valley, which is typically quite dry. I was intending to finish the underside with poly and the top with a thicker epoxy coat: Would that likely lead to disaster?

Last edited by mackman; 04-07-2018 at 05:51 PM.
mackman is online now  
post #31 of 34 Old 04-07-2018, 05:50 PM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
Quote:
Originally Posted by mackman View Post
According to my moisture meter, the MC of the oak is between 7% and 9%. It'll be kept indoors in the California central valley, which is typically quite dry. I was intending to finish the underside with poly and the top with a thicker epoxy coat: Would that likely lead to disaster?
That sounds alright. Go for it.
Steve Neul is offline  
post #32 of 34 Old 04-07-2018, 05:53 PM
Senior Member
 
Join Date: Mar 2016
Location: Fresno, CA
Posts: 265
View mackman's Photo Album My Photos
Quote:
Originally Posted by Steve Neul View Post
That sounds alright. Go for it.
Thanks! So you think an epoxy coat would have at least a shot at not splitting in this circumstance?

Luckily, it's for a family friend, so I would have the opportunity to repair the finish if necessary. Maybe this will be a good test case.
mackman is online now  
post #33 of 34 Old 04-07-2018, 05:57 PM
Senior Member
 
Join Date: Sep 2011
Posts: 25,995
View Steve Neul's Photo Album My Photos
Quote:
Originally Posted by mackman View Post
Thanks! So you think an epoxy coat would have at least a shot at not splitting in this circumstance?

Luckily, it's for a family friend, so I would have the opportunity to repair the finish if necessary. Maybe this will be a good test case.
With wood there is never guarantees but with the moisture contend as low as it is I don't think you will have any problems.
Steve Neul is offline  
post #34 of 34 Old 04-07-2018, 06:38 PM
Village Idiot
 
epicfail48's Avatar
 
Join Date: Mar 2014
Location: Springfield MO
Posts: 4,917
View epicfail48's Photo Album My Photos
Quote:
Originally Posted by mackman View Post
Thanks! So you think an epoxy coat would have at least a shot at not splitting in this circumstance?

Luckily, it's for a family friend, so I would have the opportunity to repair the finish if necessary. Maybe this will be a good test case.
Depends on the epoxy methinks. An epoxy meant for finishing wood will actually cure and still have some flex to it, something like Smooth On epoxy. Seriously, i have a sheet of run-off from that stuff that i poured 2 years ago, still flexible and pliable and yes, it was mixed correctly. Just meant to flex with the wood i guess.

A different sort of epoxy may not hold up as well though. Picture something like a conventional 5 minute epoxy, sets up rock hard. Try to flex it and it shatters. Stick to the dedicated finishing stuff though and id wager youd be fine

I need cheaper hobby
etsy.com/shop/projectepicfail
epicfail48 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
How to Finish a Wood Slab Bar Top Verno9 Wood Finishing 6 10-03-2017 10:15 PM
Buffing Wheel Finish - Briar Wood HHouck Wood Finishing 16 08-29-2017 08:23 PM
Rough cut lumber finish Boogeyman Wood Finishing 1 07-29-2017 08:24 PM
how to finish rough cut boards Dreadnought General Woodworking Discussion 20 04-25-2017 08:07 PM
UV darkening of wood and finish spidennis Wood Finishing 2 10-15-2015 02:38 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome