Minwax Wipe on Poly - water or oil based?

[ortho85]

Minwax Wipe on Poly is often recommended as a sealant.  I bought some but picked up gloss by mistake.  When I went back to get satin, I realised that the product sold in Bunnings (Australia) is oil based.

 

I'm trying to avoid painting the hull.  Do you advise oil or water based for sealing walnut?

 

Thanks,

 

Brett

[mtaylor]

Hi Brett,

 

Water-based will give you some issues as it raises the grain and would require re-sanding and re-applying.  Polyurethane is a finish, so glue won't stick to it and paint is problematic.  If you just want a sealer so you can paint over it, get some sanding sealer which should do what you want. 

[Pete Jaquith]

Brett,

 

I use Minwax's oil based wipe on varnish (satin finish) for sealing the exterior hull planking/copper sheathing after all attachments are complete. I use a somewhat thicker Bartley's oil based gell wiping varnish for sealing/finishing decks. I tried the water based products and was dissatsified with the results. I do, however, use water based acrylic paints.

 

Pete Jaquith

Shipbuilder

[davec]

Brett - both oil and water base work just fine, but look very different. Oil really brings out the color of the wood. The water based doesn't. I use both. I use the water based on holly. The oil based gives it a yello w tinge, while the water base preserves the white. I use the oil based on everything else.

 

Dave

[mog]

Sanding sealer works very well , clear smooth, very hard finish, fills in minor defects,     however you want to stain, put at least one  good well rubbed in coat  first, then seal. Light sand and stain again   if desired. I often rub stain over the seal, attempting to gain a different effect.  As with any finishing it’s all trial and error on scrap wood to get the effect you like.

MOG

[Blue Pilot]

I use both.  I agree with davac above that the oil based will give light wood a yellowish tint you may or may not want.  So on light wood like bass or holly use the waterbased otherwise I like the oil based.

[Modeler12]

 

Hi Brett,

 

Water-based will give you some issues as it raises the grain and would require re-sanding and re-applying.  Polyurethane is a finish, so glue won't stick to it and paint is problematic.  If you just want a sealer so you can paint over it, get some sanding sealer which should do what you want. 

Careful Mark. Minwax is also a polyurethane and apparently there have not been issues about glue or paint not sticking to it.

 

I haven't used it for years (it is hard to clean brushes, etc and does not last long in an opened can). Instead I am a firm believer in water based urethane (Varathane in particular). I have used it on many pieces of furniture and other projects and never had a problem with PVA, epoxy or CA glue sticking to it.
The issue of the grain rising because of the water is, in my opinion, not that critical as long as you apply a thin coat. However, if you use water based stain (and apply a heavy coat) then, yes, fibers tend to raise their head up into the air. But a light brushing with fine steel wool takes care of that quickly.

[ortho85]

Thanks for the replies - but I'm more confused than ever (and that's saying something!).

 

I guess I'll take MOG's advice, and test a few methods.

 

I'm mainly looking to seal and finish over bare or painted top layers of walnut, so the glue is not a concern.  Off to experiment!

 

Cheers,

 

Brett

[Modeler12]

That's the way to do it Brett. 

 

However, if you don't mind, I would like to make one more comment about glue and paint 'sticking'. It really is a matter of degree in strength. 

I don't think we should bluntly say that glues and paint don't stick to wood surfaces that have been treated with any of the above mentioned materials. Surely it would be ok to say it is no good when you try to use carpenters glue to bond two pieces of metal or glass. But a product that is meant to be used on wood will produce some degree of strength when bonded.

 

Just for fun I bonded two pieces of oak scrap that had a couple coats of urethane finish; two more were bare wood. One set was with CA glue, the other with PVA. Results???

I had to use a hammer to shear off the joints on all of them. I'll grant you that the bond area was about one square inch and the one with the PVA on bare wood was definitely stronger. But for all practical purposes, I would not hesitate using any of them for 'casual' bonding.

[Modeler12]

From my experience until now I have 2 confirmed NO's which I try to take into consideration:

1./ Carpenter's glue does NOT stick to a surface which had been oiled (by Scandinavian Oil or Danish Oil in my case)

2./ Superglue does not stick to a surface which had been stained with Feat Watson stain.

 

I proved these quite a few times for myself already but I still try these things again and again in a rush - and then the swearing session begins!

Janos 

Janos, I am not surprised that real oil does not work. But then there is 'Tung Oil' which does work.

Here is what I did. Took a couple pieces of bare oak (3/4 x 3/4), applied some Minwax tung oil and within five minutes applies some CA and clamped the pieces together. After a couple hours I was able to break them apart very readily.

Then I repeated this. Applied a heavy coat of tung oil but let it dry (cure, whatever you want to call it). Then a few hours later I put on the CA, clamped it and about 24 hours later tried to break the joint. No go. I had to use a hammer to shear the pieces.

My contention is that if the material has a chemical reaction that provides a 'hard' surface (as well as some penetration of the wood), some reasonable bond strength can be expected with CA, PVA and epoxy. If it is real oil, grease, wax, etc than all bets are off.

[Modeler12]

Jay

Interesting. I did not try CA this way yet, but I will!

Janos

Ok, Janos, and thanks. Please let me know how those 'oils' work out.

I also would recommend not to be in a hurry when it comes to surface preparations. Most of this stuff takes time to 'heal' or cure.

 

I may sound like an expert (sorry, didn't mean to), but after about thirty years of industry experience (and a lot of wood-working besides) I still maintain that the 'new' is not all that much different from the 'old' when it comes to common sense. 

Meaning that

1. anything 'grease' should be avoided.

2. let it cure or give it time to do so.

3. don't bond metals to anything with PVA (it is intended to chemically link to fibers, not metals).

4. be careful with bonding plastics (there may be a release agent on the surface). Solvent types are ok.

 

Would anyone like to add to this?????

[ChrisLBren]

Sure Ill add to the discussion - I use pure tung oil as a finish.  In order to glue a part to the finished surface - all you need to do is sand the area with 320 grit or scrape.  Then you glue (PVA or Cryno) - and after dry reapply the oil for a perfect finish. 

Chris

Edited May 23, 2014 by ChrisLBren

[Modeler12]

Janos, first of all, I always liked your carving skills and results. I wished I has some, even a tiny bit of yours would help.

 

Since I am not familiar with Feast Watson stain, I cannot comment about that. But, like I mentioned about the Tung oils experiments, if the surface is still 'wet' and you apply CA (or PVA) too soon things go wrong. Some epoxies react when wet (water) but that is not the norm.

[Modeler12]

Sure Ill add to the discussion - I use pure tung oil as a finish.  In order to glue a part to the finished surface - all you need to do is sand the area with 320 grit or scrape.  Then you glue (PVA or Cryno) - and after dry reapply the oil for a perfect finish. 

Chris

Chris, again you are doing it right with 'pure tung oil'.

But would you agree that it takes some time to have that finish 'cure', settle, or harden, before you do the next step? Are you doing the sanding or scraping after the tung oil has saturated and the surface is nice and smooth?

If you can sand it, it must be free of 'oil', NO??

[ChrisLBren]

Hi Jay,

My process with pure Tung Oil is simple - apply first coat thinned 50 percent with mineral spirits (this is key for your base coat for maximum absorption) - let dry for 24 hours.  Lightly steel wool with 0000 - then apply second coat full strength - let it sit for 10 -15 minutes then buff with t shirt - watch for seepage (you shouldn't get much - since you thinned your base coat). Again let dry for 24 hours - steel wool and apply final coat full strength and remove excess after 10 minutes or so.  Let dry 24 hours and you're done - I don't steel wool final coat.

 

Keep in mind this is using pure Tung Oil on a hardwood (in my case Pear) - you should be good to go after letting the final oil coat cure for a few days.  I've never had a problem glueing a part to a surface i have applied this finish to - again you do need to sand or scrape the area you will be glueing the part to - then just reapply some oil after the part has dried - works like a charm.

Chris

[dgbot]

Chris,  instead of steel wool have you experiemented with bronze wool?

David B