Help applying dope with all this humidit...

I have tried to apply clear over my nitrate and silkspan fuse twice now and I am getting an orange peal finish. I'm using Brodak clear with about 40% thinner and 10% retarder. I am using a brush (I haven't got a compressor yet). It does fine over the open bays of the wing but just wants to bubble up over the hard surfaces. What am I doing wrong? PLEASE HELP!!
Butch

First sand all the clear dope off the substrate (nitrate and silkspan). Then wipe with paper towels (don't trust old tee shirts, etc) soaked in prepsol or thinner or some type of prep to remove any and all oils. Oils can and do get on the surface from the air, our hands, etc. I ran an engine in the garage one rainy day to hurry up and get it ready to place in a plane. The castor fumes settled on everything and for a week I had fits trying to do any type of painting. Next time the engines run in the rain, whether they like it or not:-).
When painting dope with a brush, use a 1 inch or at least a 3/4 inch brush with good hair, not a cheapy. Reduce the clear to at least 50/50 or 50% dope, 20% retarder and 30% thinner. Brush a fully loaded brush in ONE direction only and use short strokes of about 2 inches. Dip the brush and do again. Take your time. After the dope has set for one day, sand it with 320. Wipe again with prepsol and do the second coat, same mixture. Ditto a third coat. Sand again then appy a base coat of silver or gray and sand and mask and apply your color coats. My biggest advise is to get a compressor and use spray equipment. It's not all that expensive and the time saved and quality of your work will be better. Others will be along with their technique and answers, so wait until you read them all. Tight lines.

Ty, Thanks for responding. So let me get this right, it might not be the humidity or the mixture but because it has been sitting for a while before I applied the clear, oils or whatever settled on the surface causing the orange peal look? I can deal with that. I thought I was mixing wrong or got some bad dope or something. Thanks again maybe I will give it another shot this weekend.
Butch

Hi Butch. The orange peel look is from the paint being too thick and drying before it gets to flow to an even thickness. The 20% retarder and 50% thinner will help alleviate this. The bubbling may be caused by oils settling on the surface. Be sure to sand until you think it is done, then sand somemore . Remember, with dope that drys fast, you can't paint with back and forth strokes, like enamels for instance. Just use 2 or 3 inch strokes in one direction. Let the dope flow. Make you over laps, but not too much. You'll know when you go too far. This is just one of those things that only practice will show.

One more Question. Can I use Sig color dope products over Brodak dope?
Butch

>One more Question. Can I use Sig color dope products over
>Brodak dope?
>Butch

You can, and you also may run into troubles. They are both Butyrate dopes and compatible (theoretically you can mix them together).

However, they use a different thinner base. The SIG thinner, being slower drying, will eat more into the underlayers and cause softness in these layers as it skims over and will take a while to "gas off". The Brodak dope cures faster, but not if the SIG thinner eats back into it. Too much slow drying thinnger (SIG thinner, Brodak with too much retarder) and you could suffer meltdown where the thinner goes down through the layers and mushes them all together. You can also have problems with it skimming over on top and gassing underneath causing the layers to separate and bubble up.

I had a biplane (real plane that you ride in) that the previous owner had recovered using dope with enamel over the top (pretty, shiny coat). However, the bubble up problem occurred while the dope underneat continued to "gas off" and I could just take the enamel and peel it off (which I did and repainted in dope).

>>One more Question. Can I use Sig color dope products over
>>Brodak dope?
>>Butch
>
>You can, and you also may run into troubles. They are both
>Butyrate dopes and compatible (theoretically you can mix
>them together).

Beware! I have heard of very little good coming from attempting to use SIG over Brodak. They don't seem very compatible at all. I can't speak for the other way around, but they are very different animals and I would go very carefully and test a lot before trying it. I can't remember which way it went, but for example, one of the thinners will not thin the other, but instead curdles up when you try. I want to say it was SIG dope in Brodak thinner, but I could be wrong.

I use Sig Nitrate for the first coats of clear, then silkspan using Brodaks thinner and use Brodaks butyrate and colors and clear over it. No problems. I never use Sig over Broadaks paint. They are not very compatable. In fact, I had some bubbling when I tried to paint Aero Gloss over Sig dope. Stick to one brand for the entire plane. The Sig Nitrate as a basic balsa filler is ok.

>The 20% retarder and 50% thinner will help
>alleviate this.

Add more thinner, and be very careful using retarder. What some of us call 50% thinner, is really equal parts of thinner to dope. That is a starting point, thinned 100%, or one to one.

Also be careful mixing brands of products. If you value your time, stick with one brand throughout, and try to keep things simple. Nitrate, and other tricks can bite you back.

I would just lightly sand your model and give it several coats of thinned clear. You can thin clear to silly numbers, so don't be afraid to go 2 parts or more of thinner to one part dope, just don't over-brush it.