# Frustrated first-timer has questions about using spar urethane



## SierraTrout (Sep 29, 2016)

Hello. I am refinishing a 30-year old solid wood entryway door which was previously stained, not painted. I am currently working on the indoor-side where the stain was still in excellent condition but the topcoat needed to be redone. I am using Varathane Spar Urethane, Oil-Based, in Semi-Gloss (I chose a spar urethane because I’ll also be refinishing the outer side of the door). I sanded the indoor-side with a fine grit. With the door lying flat, I applied the first thin coat using a high quality natural brush and with the product diluted to 50% urethane/50% mineral spirits. Right away I noticed that some areas were dull while others were shiny. I don’t know whether it’s because I applied the finish unevenly; whether some areas “absorbed” the varnish more than others; or whether the product is faulty. I stirred the varnish thoroughly before applying. Is this common for semi-gloss spar urethane? Will the shine be consistent all over after additional coats?

Another concern is drying time. The product container says that drying time between coats is 10-12 hours (and this is at full strength). I expected my first coat to dry faster as it was diluted 50-50. The weather daytime high was mid-80’s; the evening was low 60’s; humidity 40%. At 12 hours the finish was slightly tacky. At 22 hours the finish was drier but not hard and smooth. I tried a fine grit on a small area and while the paper didn’t “gunk up,” the sanding wasn’t producing a fine powder nor a smooth surface, and it would be possible to scratch the surface with a fingernail. Am I doing something wrong or is this typical? Should the surface be hard and fairly smooth to the touch before applying additional coats? I have guests arriving in 9 days and the door needs to be back in place by then. At this drying rate, I don’t think it’s possible to get the interior and exterior sides done. I’m willing to consider switching products, if that’s what it’ll take, like possibly a water-based varnish. Or would it make sense to reinstall the door on its hinges (but without the other hardware) and continue to apply the finish using the wipe-on method so it can be done vertically? I know that method involves several additional coats but at least the guests can come in through the front door instead of through the garage. I would really, really appreciate your ideas and help.


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## Jim Frye (Aug 24, 2016)

50/50 dilution produces wiping varnish. Wiping it on produces much thinner coats that will cure faster. Brushing this mixture on likely left a lot of finish on the surface. First coat may well have soaked in in spots due to the mineral spirits and produced the dull areas. Also other areas that did not soak in would dry slower due to the thicker application. At this point, I would let the entire application cure before any sanding. Normally, I thin varnish 10 to 20 percent for brushing, depending on the brand and type. Finishing the door vertically with wiping is doable, but runs and sags are more prone to occur so more care is required.


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## jorma (Feb 24, 2016)

A lot pf Paint thinner (unless this was new wood) may very well take just as long to dry. It probably just sucked in, in some spots, and others that had more existing finish are taking longer to dry.
Oil base Varnish/Paint takes Several Weeks to cure. There is no way it is going to powder up the next day.
For inside, or even outside if the door does not see The Sun, you might want to use a Non-Spar Varnish.
When i read "Spar" i think of varnish that is meant for heavy sun and weather, and is not necessarily meant to dry "hard" like Varathane does.
For what you are doing inside, i would prefer something like Polyurethane or the original Varathane brand if that is still being made.
Even the "outside" Deft Defthane does seem to dry Faster/Harder than something that says "Spar" on it.
Talk to somebody at your local:
Kelly Moore
Sherwin Williams
Dunn Edwards
paint store
Or maybe just pick up some "Poly" at Home Depot.


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## Steve Neul (Sep 2, 2011)

The experience I've had with varnishes is it takes a lot longer to dry if you thin it. At this point I wouldn't worry about it though, just wait it out and I mean wait it out. You can't rush it, the finish has to take it's own time. If though another day and the finish doesn't dry then you might worry you left some paint stripper on the wood. 

Thinning the first coat will make a better bond but I would not thin it anymore for the next coats. It's also normal for the first coat especially if you thinned it for there to be some shinny spots and some dull spots. The wood has hard and soft spots and the soft spots just drink up the finish. This should get a lot better with the second coat.


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## SierraTrout (Sep 29, 2016)

Good morning, everyone, and thank you for your responses. It was hard being in limbo all day yesterday, but thanks to you I feel much better about this project's outcome.

Jim - I was using the 50/50 dilution as a sealer, and also to practice brushing varnish as I'd never done it before and I was worried about the dreaded brush marks and dust nibs. Sadly, everything I know about stain and varnish is from the internet! After this coat my plan was to use a 10%-20% dilution. It's good to know that working on a vertical door can be done ... carefully. Thanks, Jim.

Jorma - Thanks for the comment about not expecting powder. I thought I had read that producing powder was one of the ways of knowing the surface was ready for another coat. Our front door is fairly recessed and does not receive direct sunlight, and our temps here in California are mild, so I will definitely consider a non-spar varnish. I thought all varnishes dried to the same hardness, so it never occurred to me to put a different type of varnish on each side of the door. I asked some questions about this project at a local paint store and the guy kind of brushed me off, maybe because I'm a woman? Anyway, I'm glad this forum is taking me seriously. Thank you.

Steve - I'm glad to report that after 36 hours the door was finally dry. Thanks for the reassurance that I probably haven't ruined the door or wasted all this time, and I will definitely go with less dilution on future coats. Have a great day!


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## Steve Neul (Sep 2, 2011)

The best way to eliminate brush marks is to make as few strokes with it as possible. The more you brush the finish the more air gets into it and it sets up too fast holding the brush marks in place. With fewer strokes the finish tends to flow together almost eliminating the brush marks. The softer the brush you use will also make it easier and better.


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## Rick Mosher (Feb 26, 2009)

If possible I would use a foam roller to apply the varnish to each area and then tip off with a quality brush. That is the best way to get a smooth surface, with an oil based product a few drops of linseed oil will help the finish flow out better and cover any brush marks. Don't use too much though because the linseed oil retards the drying.


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## SierraTrout (Sep 29, 2016)

Steve - Thanks for the great advice. Yesterday I actually switched to a water-based poly (and a soft synthetic brush) for the interior side of the door in order to speed things along. The poly was ridiculously easy to apply after dealing with the spar varnish. It leveled well with an even sheen, and was smooth and sleek to the touch after 1 hour. The instructions said I could re-coat in two hours without sanding (using a chemical bond, I guess); but I decided to wait 24-hours, sand, and then re-coat. After this recent success I'm tempted to give up on using the oil-based spar on the exterior side and go to a water-based. Again, thanks for your help.

Rick - I hadn't heard of the foam roller technique or the use of linseed oil. Thanks for your help.


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## Steve Neul (Sep 2, 2011)

SierraTrout said:


> Steve - Thanks for the great advice. Yesterday I actually switched to a water-based poly (and a soft synthetic brush) for the interior side of the door in order to speed things along. The poly was ridiculously easy to apply after dealing with the spar varnish. It leveled well with an even sheen, and was smooth and sleek to the touch after 1 hour. The instructions said I could re-coat in two hours without sanding (using a chemical bond, I guess); but I decided to wait 24-hours, sand, and then re-coat. After this recent success I'm tempted to give up on using the oil-based spar on the exterior side and go to a water-based. Again, thanks for your help.
> 
> Rick - I hadn't heard of the foam roller technique or the use of linseed oil. Thanks for your help.


If you have started the door with an oil based spar I wouldn't put a water based spar over the top. It's not likely to adhere very well. 

When I finish a door with a brush you kinda have to go all the way across the width of the door at the top and then work your way down going back and forth across the width of the door, always brushing in the direction of the grain. This keeps a wet edge while you are working your way down the door. With a varnish if you brush on a spot and then work another area and go back the finish will set up to the point the brush will hang in it and drag as though it was glue. 

Another thing that would help you brush it is Flood Penetrol. It's an additive you can add to the varnish that would slow down the drying time.


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## SierraTrout (Sep 29, 2016)

Wow, Steve, you explain things well and I get what you're saying. I guess I should give the oil-based spar another try, and will check out Flood Penetrol if I run into trouble. Thank you!


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