What varnish to use on a canopy?

[tcoral]

what type of finish is good to use on an aquarium canopy? I bought both Varathane diamond spar Urethane but it says for outdoor (exterior) wood with no mention of interior use. It dries clear which is a plus on my reddish wood finish.

I also have indoor/outdoor Helmsman Spar Urethane, but being oil based it'll dry with a yellowish cast?

Many of the others that say indoor/outdoor and are good against water are oil based and have a golden cast, which I don't think I want.

So the question is, what is a good finish to use on a canopy? How clear is it? Is it safe to use Varathane Spar Urethane outdoor, indoors? I also want something that's safe after curing for me and my aquarium

 

[Donw]

Outdoor just means it can handle the moisture. Its perfectly safe after it cures for indoor use. Spar in general will cast a yellow haze including the diamond. Spar will give the stand great protection but is not a great finish in terms of look and feel. Any poly including the waterbase poly's will provide ample protection. If done right the newer water based poly's are great. Laquer will provide protection and grain clarity but is nasty to apply.

Don

 

[Phyxius]

I used the polyurethane on the outside of mine and its worked great. I have heard of people using the Helmsman Spar Urethane on the inside of the canopies since its an " outdoor" version of the urethane.

I just painted the insides of mine with white marine enamel and the outside with 2-3 coats of poly..

 

[tcoral]

Thanks! What brand and type of finish would you recommend? I saw on the water based minwax poly that it couldn't be used over their Mahogany stain but they didn't say why. I want to make sure I get the right one! Also, I'm trying to match the pre-made stand, so a yellowish finish may throw off the match.

 

[Phyxius]

Check out their website and see. I remember reading some things about the water based stuff being used ONLY with certain stain products like you said...
Sorry couldn't be more help on it. I have always used the Minwax Fast dry poly on mine


Heres a link to Minwax to check above though if it helps
Urethane

 

[Donw]

Minwax finishes are quirky so you have to follow manufactures suggestions. I'd use a better brand of finsh especially if trying to match a commercial finish.

Don

 

[tcoral]

OK, did some more research online and it seems like the mahogany stain has a lot more or a type of pigment that interacts and changes color with the water based polyacrylic product. (the Minwax site says that their Polyacrylic is incompatable with their mahogany stain.) The Varathane product I got is water based too, so maybe I shouldn't risk it with that either? So I guess that leaves the Helmsman? There was another Spar product too that I saw and was debating on called McCloskey Man O'War Spar Marine Varnish. It says it's OK on Mahogany wood but how about the stain? It's an oil based product so it should be OK?

 

[Donw]

All top coats will lift some of the stain especially if its dark. They say it ok on mahogany because they are selling spar to boaters and want the boat market. Stain the wood and use a sanding sealer or dewaxed shellac over the stain and the lifting will be minimized.

Don

 

[tcoral]

I think there's more to it than lifting:

Looking at the Minwax site FAQ they said:

"Q. Can Polycrylic® be used over Minwax® Wood Finishâ"žÂ¢ stains?

Yes, provided the Wood Finishâ"žÂ¢ has dried completely, which generally takes 24 hours. The one exception is over Wood Finishâ"žÂ¢ Red Mahogany Stain. Polycrylic® and Red Mahogany are not compatible. "

Also, online someone tried the two together and it totally eliminated the red pigment turning it brown. Maybe I should be safe and use their Helmsman product. . (on a test scrap first of course ). Now looking at it I used Mahogany Gel Stain, I wonder if that's the same as the Wood Finish product?

 

[Donw]

Thats why you use shellac or laquer based sanding sealer. It will lock the stain and the top coats will just be top coats. Shellac is alchol based so its dry in less than a minute and laquer is solvent based and will be dry in 5 minutes. The top coat wont be able to react with the stain.

Don

 

[38bill]

IMO water based poly sucks. It dries too fast and will leave brush marks and it doesnt want to flow out smooth like a solvent based finish will. It also wont give you the "depth" that a solvent based finish will, as it tends to look "flat". I think the big difference in most int poly and ext poly is that there is UV protection added to the varnish. I believe the Helmsman uses a iron compound and this will darken the finish. I actually like the darker finish when used with a heavy grained wood like oak. I think it evens out the color.

 

[Logzor]

+1 that polyacylic is a nightmare you can not get the brushstrokes out.

 

[Donw]

<a href=showthread.php?s=&postid=13334117#post13334117 target=_blank>Originally posted</a> by Logzor
+1 that polyacylic is a nightmare you can not get the brushstrokes out.

Thats operator error or the brush itself. Its self leveling and with practice you can get real close to a sprayed finish.

Don

 

[tcoral]

<a href=showthread.php?s=&postid=13333559#post13333559 target=_blank>Originally posted</a> by 38bill
IMO water based poly sucks. It dries too fast and will leave brush marks and it doesnt want to flow out smooth like a solvent based finish will. It also wont give you the "depth" that a solvent based finish will, as it tends to look "flat". I think the big difference in most int poly and ext poly is that there is UV protection added to the varnish. I believe the Helmsman uses a iron compound and this will darken the finish. I actually like the darker finish when used with a heavy grained wood like oak. I think it evens out the color.

Ok, tried both the varnishes on a stained scrap. I agree that the water based looks flat. It also isn't as shiny. I got the semi-gloss solvent based and it's shiny! Also, the waterbase isn't as smooth and got bubbles. I guess that solves which one to use.

 

[Donw]

<a href=showthread.php?s=&postid=13336921#post13336921 target=_blank>Originally posted</a> by tcoral
Ok, tried both the varnishes on a stained scrap. I agree that the water based looks flat. It also isn't as shiny. I got the semi-gloss solvent based and it's shiny! Also, the waterbase isn't as smooth and got bubbles. I guess that solves which one to use.

Water borne need a nylon brush and oil a china bristle brush. NO brush is usable right out of the package. Both need to be soaked in mineral spirits for a few hour but preferably over night. Lightly ring out the brush just before use and you will have no bubbles. This will flow the finish rather that brushing it on. Clean the brush frequently.

Don

 

[tcoral]

Thanks Don, I can tell though that the water base has a different finish quality than the oil based one though (maybe the difference in brands)? I don't think I like the exterior one. Asked Minwax directly on the stain compatability and here was their answer:

"Thanks for taking the time to contact Minwax. There will no compatibility problems with using Polycrylic over any Gel Stain colors. The Polycrylic mutes the red tones in the Wood Finish Red Mahogany stain so we had to make the warning."

So it's OK. I didn't see any changes to the color using either stain, and I had to use tintsall to increase the red of the Gel Stain too.