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-   -   Ultracote covering over Auto Primer?? (https://www.rcuniverse.com/forum/questions-answers-154/11618047-ultracote-covering-over-auto-primer.html)

dksnyder 06-05-2015 10:55 AM

Ultracote covering over Auto Primer??
I just built a kit wing. The LE balsa sheeting was very old, dry and weak. It would crack whenever I put any pressure on it!
I covered it with very light weight silk and thin CA. It greatly improved the strength, but is was not very smooth and even!
I used gray auto "sandable primer" to smooth things out.(Iron Armor brand, said it was good for metal fiberglass or wood.)
It worked OK, but I was left with "blotchy" gray and (balsa) tan spots. II tried to cover with Dark Yellow Ultracote.... the spots showed thru terribly!!!
Now I don't know what to do....
It didn't seem that the Ultracote adhered as well to the primer as is does on wood. Maybe it's OK.... but, not sure!!
I would like to paint over the primer, or use another coat of primer (maybe white primer, if I can find it)

What would you suggest? Even coat of primer (white or gray), or paint over the primer (what paint would be best?)
Does Ultracote work on painted surfaces?
Should I apply "Balsarite" (can this be applied OVER the primer?)


Don Snyder

Gray Beard 06-05-2015 06:13 PM

Ca shows through ultra as a dark spot, I have used lacquer white paint over areas that had filler on it so it didn't show through the covering and it stuck well. The heat tends to soften the lacquer and the covering adheres well to it. Yellow is still a very light opaque color and often shows through any blems.
With really old kits I bring the kits into the bathroom so when we shower the wood absorbs the steam/moisture. I leave them in there for a week or two.

dksnyder 06-05-2015 07:04 PM

Many thanks for the response, "Gray Beard" (LOL..... love the moniker)
That's just the info I needed. Sounds like I will be able to save the project....
What brand/type lacquer paint do you suggest?

Gray Beard 06-05-2015 10:25 PM

It's not something I have done often or recently so I had to go look. I think it was the LusterKote but I have a few other brands out there in white but the LK is a lacquer. Only time I use primer is when I glass and paint or on glass parts I'm going to paint.
By leading edge did you mean the true LE or the sheeting?? I'm thinking sheeting because I can't understand anyone putting pressure on the leading edge that would crack it.
If it's the sheeting then wet it before you try to shape it and glue it down. I use a 50/50 blend of water and ammonia and only spray one side, the top side and as it soaks in the wood it will bend to shape easily if you do it slowly. I have several of those spray bottles you can buy at the dollar store. I'm old school and use the ammonia but even just straight water will work.
Gray Beard was a hunting accident and I have kept the name in memory of a friend. It was really only used for three days and then forgotten. The name was used with great effect though.

jaka 06-10-2015 07:11 AM

5 Attachment(s)
You should not have use CA glue! When you want to reinforce a thin balsa surface, instead you should have used 24-30 hour epoxy (or polyestser resin) and 25gram glass fiber.
All plastic films are easily stuck to a balsa surface covered with thin glass fiber. Here is how I rebuilt and recovered my "Viper" Q-500 racer using 24 hour epoxy,brown micro balloons and 25g glassfiber when the tail got cracks.Covering is Oracover (Ultracote to you Americans).
Plastic film does not stick to a primed surface!http://www.rcuniverse.com/forum/atta...mentid=2101833http://www.rcuniverse.com/forum/atta...mentid=2101834http://www.rcuniverse.com/forum/atta...mentid=2101835http://www.rcuniverse.com/forum/atta...mentid=2101836http://www.rcuniverse.com/forum/atta...mentid=2101837

dksnyder 06-11-2015 09:43 AM

Thanks jaks,
I found the Ultracote to not stick (well) to the primer, as you suggested.
I'm well past the point of using glass cloth and epoxy...( too heavy, anyway)
So, I'm stuck!
I have since painted over the primer with a lacquer paint.
One reader said the covering will hold well over lacquer paint.
(I HOPE SO!!!)

jaka 06-14-2015 05:17 AM

It will not!
Sand it and cover it with thin /light 25g glass/epoxy....or replace the balsa with sturdier sample.

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