Which clear coat is better for fiberglas door?

2ajsmamaSeptember 10, 2009

I "painted" my f/g Thermatru door with Zar oilbased stain. I want to clear coat it on Sunday (next day the sun is out). I have either Thermatru water-based poly that is supposed to last for 5 yrs, but my can expired "21 20.09", or new can of Sikkens Cetol Door and Window Clear Satin.

Thermatru can be recoated in a matter of hours, no sanding between coats. Recoat as necessary to maintain gloss (satin), just wipe door down with mineral spirits first. However, there is the expiration date problem. Does this stuff turn into a pumpkin as soon as it reaches the "best by" date? Thermatru has given me 2 different answers the 2 times I've called (guess I should call again?).

Sikkens Cetol D&W requires 24 hours between coats (OK if Monday and Tuesday are sunny as well), but brochure just says "contact Tech Support" about prep for fiberglas. I'm worried about maintenance. It's supposed to last 2-3 yrs on southern and western exposures, 3-4 yrs north and east. I have west-facing door but a 7ft deep front porch, the late afternoon/evening sun gets intense (esp. on bottom of door) in the summer, rest of the year not bad. So maybe I'll get 3 years. But then what do I have to do to recoat it? Sand it? Strip it?

Which would you use?

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We've got many Sikkens products at our ACE...
The Door & Window series is some nice stuff!

Your maintenance...
* No, you don't have to strip it!! Yay!
* It's GRREAT you have a covered porch protecting the entry. Because of this, you may get "5 yrs. off" between maint.-coats!
* For the maintenance: Wash the door, let dry. If you can, take door off.
* Evenly scuff-sand so door is evenly-dulled. Use ~ 100-120-grit paper.
* Remove every molecule of dust!
* Then just re-apply an even coat or 2 of your D&W.
* If you use this "stay-ahead-of-the-damage" approach (Sikken's mantra...), the door will look great for many years.


    Bookmark   September 13, 2009 at 12:54AM
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Thanks Faron. Sand a f/g door? Ahh (shudders)! I guess if I have 3 coats of D&W on I'd only be sanding the finish, not the door. But do you have to sand b/t coats when you're first putting it on (allowing no more than 24 hrs b/t coats)? What do you wash it with? Do I have to wash it before I put the first coat on today or tomorrow? Maybe wash today and let it dry, start coating tomorrow?

We have a gravel drive so I will never be able to remove every molecule of dust (at least from the sidelights, we can take the door off if DH promises not to hit the ceiling again, don't want to have to repaint the ceiling every time we recoat the door LOL).

I didn't post over on other forum, I never know what to say, and have been emotionally exhausted myself (memorial service for my godfather yesterday). But how's Sashi doing? I guess I should post to roselvr too. ((((HUGS))))

Thanks and take care.

    Bookmark   September 13, 2009 at 7:55AM
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The covered porch will greatly extend the life of the coating, but a storm door with a glass panel will greatly decrease it if you have sunlight shining directly at the door at any time during the day. That makes it like an oven in between the storm door and the door itself, almost like cooking the finish. If you use 100 grit sandpaper, you will likely remove some stain, which is really something you do not want to do. The worst part about these Therma-Tru doors is that if you actually remove stain or nick it to where you need to touch it up, it's nearly impossible to get it to blend in, even if you are using the exact same stain you used when you originally stained the door. This is why it is imperative that you do not let the weather wear away that topcoat protecting the stain. I usually have an old, beat up sanding block on hand that hardly has any grit remaining to sand the doors before re-finishing them. Really, you just want to knock down any remaining sheen some before recoating.

    Bookmark   September 13, 2009 at 10:48AM
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Thanks paintguy - I emailed Sikkens and hope to have answer tomorrow about how to prep the stained door for the first coat of Cetol. I don't have to sand it before the first coat, right? Just scuff it between coats? Or only when adding a coat every few years, and not in between the initial coats (as long as I don't go more than a few days between coats)? What grit do you recommend? Used 220 paper? Scothbright (what color?) pad?

I don't have a storm door. I tried talking DH into a screen door but he didn't even want that since we have AC, he and DS have allergies so he'd rather run AC than open windows/doors. I guess I shouldn't have bothered ordering a screen for the slider when we built the house (or screens for any of the windows) LOL.

    Bookmark   September 13, 2009 at 5:00PM
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Yeah, no sanding until you need to recoat the door. I would only sand in between coats if it is rough and it really shouldn't be because it is not wood so the grain should not raise. I may even opt for 400 grit.

    Bookmark   September 14, 2009 at 12:42AM
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Thanks - I have to do one coat a day on door *and* sidelights b/c I just checked the weather, Wed may be cloudy, 20% chance of showers and the rest of the week til next Wed is even worse! So can I start today after just wiping them down with mineral spirits/naptha instead of washing and letting it dry first (Sikkens brochure says let it dry 3 days - not often we have a solid week with no rain this year!)?

    Bookmark   September 14, 2009 at 6:28AM
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I called this morning, Tech rep told me just wipe the door down with a damp cloth to get the dust off, no need to wash with TSP or use any solvent on top of the stain. Wait til the dew burns off and air is not humid to brush first coat on - said it should level nicely, don't thin. Wait at least 24 hours for the second coat, even a week should not be a problem. No sanding or solvents between coats, shouldn't even have to wipe down with water (unless it gets really dusty before I can get to the second coat). Just make sure to finish each coat at least 6 hours before the temp starts to drop and it starts to get humid again. Only 2 coats required for fiberglas.

    Bookmark   September 14, 2009 at 9:28AM
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Well, this afternoon I got an email back from Sikkens saying "We do not recommend our products over another stain. On a fiberglass door you apply 2 coats of Cetol Door & Window over an oil or acrylic primer."

So wouldn't a heavy (painted-on) coat of Zar oil-based stain count as an oil-based "primer"?

I'm putting the second cost on tomorrow, I don't plan on stripping and starting over. Should I expect some kind of problem?

    Bookmark   September 14, 2009 at 5:46PM
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No. They just say that to avoid liability. Generally speaking, it is best to stick with the same systems, but Sikkens does not make a stain that works well on fiberglass doors. None of them are heavily pigmented like the stains you can get from Therma-Tru. It's strange that they would say anything about a primer when you are staining the doors. I have been using the Sikkens finishes over several other stains for at least 15 years with no issues.

    Bookmark   September 14, 2009 at 6:46PM
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Thanks paintguy. Should I put on 3 coats if weather permits? I found out the hard way what you mean about the doors not touching up. I tried pulling a hair out of the sidelight (I know I got hairs on the door bending over the sawhorses, but I managed to get one on the bottom panel of one sidelight). Didn't get the hair out, but chipped the stain a little, wouldn't cover with an artist's brush so I ended up using a toothpick and dabbing it on. Clearcoated over it, dabbed more on over the clearcoat (that went on easier). I don't think I want to hang a wreath or anything on this door!

I was thinking 3 coats would be more durable than 2. Why do they say 2 coats on fiberglas and 3 on wood? Is that minimum, and 1 more is better (and eventually you'll get a lot more - I don't know at what point you have to strip instead of adding).

    Bookmark   September 14, 2009 at 7:37PM
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Well wood is wood and fiberglass is fiberglass. Wood has a porous surface and will expand and contract. Fiberglass is not porous and will never expand and contract. Therefore, it's easier to reach a point of maxiumum saturation (the point where successive coats are not sinking into the substrate any further) on a fiberglass surface than it is on a wood surface. The reason we apply more coats is to get better film build because it looks better and seals better but that can be achieved on a fiberglass door in two coats.

    Bookmark   September 15, 2009 at 12:48AM
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Yeah, I figured wood needed more coats b/c it's porous. But the question is, is 2 coats the minimum for f/g and would 3 be better for the initial coating? May be a moot point b/c of weather.

Today will be sunny and 70's, but they said to wait *at least* 24 hours b/t coats. That doesn't give much leeway for the "finish 6 hrs before it starts cooling off" (sunset) guide. If I finished at 11:45am (took 45 minutes to doo do and 2 sidelights), when can I start today? Anything after 1pm is pushing the 6 hr rule.

The next day with no precipitation and temps near 70 during the day, over 50 at night will be next Monday. Is a week too long b/t coats (1st and 2nd or 2nd and 3rd)? Esp. if I want to leave the tape up - will the first coat have hardened so much I won't be able to get it off clean?

    Bookmark   September 15, 2009 at 6:50AM
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I wouldn't worry too much about an oil based coating being wet when the temps dip at night. It's still going to continue drying even though it is colder. It will just dry at a slower rate. Now, if it were going down to freezing or below that would be different, but it's still summer. The door is safe to recoat if it is dry. If you can stick your hand on the door and rub the door and not feel any tack at all, then you are safe to recoat. Yes, I have done three coats on fiberglass doors and it is better than two coats, but if the door is protected from sunshine by an overhang, then that extra coat is less important.

    Bookmark   September 15, 2009 at 7:55PM
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Well, I took all the tape off today so I guess I won't do 3rd coat on the sidelights, but I may do another coat on the door (did one coat under middle hinge yesterday, bottom hinge today, so still have top hinge to unscrew and seal under). Is it OK to wait til Sat? Now that looks like the next nice day.

The bottom of the door/sidelights really gets hit by the sun - I opened the door all the way to dry *inside* today b/c this afternoon the sun was so intense! Maybe I should tape off the sidelights again and put another coat on them?

I had some stain leak under the tape so I have some touchup to do on the jambs - not a nice clean line, and even some spots where I overlapped the tape and stain leaked under, let a couple of good splotches in the middle of the jamb. When can I safely tape off the sidelights without peeling the Cetol off?

Thanks for all your help.

    Bookmark   September 15, 2009 at 10:14PM
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