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-   -   Sig Koverall and Minwax Polycrylic (https://www.rcuniverse.com/forum/kit-building-121/10563983-sig-koverall-minwax-polycrylic.html)

sensei 06-10-2011 05:00 AM

RE: Sig Koverall and Minwax Polycrylic
 
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I love covering with the Stits Lite and Dacron cloth from Aircraft Spruce & specialty, the cloth comes 72" wide and any length you want to order on the roll. This stuff is so easy to use, tighten, and finish, that I just say enough good things about it. Here are just a couple of airplanes that I have used it on over the years.

Bob

Lone Star Charles 06-10-2011 09:13 AM

RE: Sig Koverall and Minwax Polycrylic
 


pacoflyer

Hi Paul

I use the Stits Poly-Tak to hold the fabric to the frame. It seems to work best when I use a brush to paint on the Poly-Tak around the perimeter of the frame and then imbed the fabric into the P-T. I usually will then go over the glue line with another coat of Poly-Tak thinned about 50-50 with MEK. Let it dry overnight before trying to shrink. If you get to much P-T on the fabric, it will make a mess on your iron, but does not seem to hurt the final finish.

Charles</p>

Rcpilot 06-10-2011 09:27 AM

RE: Sig Koverall and Minwax Polycrylic
 
1 Attachment(s)
Bottom has 2 coats of polycrylic now. Time to sand. You can see the brush marks. I was very careful to only brush from LE to TE. Never sideways. At least all the brush marks go the same direction. Can still see some of the seams, but they are beginning to disappear as the polycrylic builds up. I think part of the reason you can see the seams is it's because all still clear. I can see putting a few more coats on it - seams will all but disappear. Then prime and paint it - you'll never see 'em.

Top has 1 coat and a nasty run. I need to sand that out before I move ahead with another coat. Tried to brush it out, but it was already sticky. Wasn't coming out without making a bigger mess, so will have to let it dry and sand it out.

I'll probably put one more coat on the top this morning and then sand the whole wing this evening with 400 grit or 600 grit after all the poly is dry.


EDIT:
Tried to sand out the drip. It was still a little gooey. I was able to very carefully use an exacto knife to slice through the center of the drip. I didn't cut the fabric. Just sliced all the way across the drip from one side to the other. Then I was able to lift the center of the drip and begin to peel it up. Then using the edge of the knife blade, I peeled the drip off in a circular spiral. Not something I'd try if I had shaky hands.

2nd coat is on the top and it's got to sit for a few hours and dry.

jester_s1 06-10-2011 10:55 AM

RE: Sig Koverall and Minwax Polycrylic
 
When you guys talk about sanding between coats when filling, are you sanding over the open bays too or just the sheeted part?

crash bandicoute 06-10-2011 10:56 AM

RE: Sig Koverall and Minwax Polycrylic
 
<span style="font-family: Comic Sans MS">what do you use to sand it with? i imagine a sanding block would only get the high spots, i.e. the ribs, spars, and edges? do you use a sanding sponge or something like 000 steel wool? i covered a set of G.P. floats afew months ago with the poly-c and .5 oz. glass cloth that turned out real nice, but that was solid structure sanded with the 3M sponges and then 000 steel wool. appliance epoxy paint anda little car wax on the bottom of the floats and they were slicker than a babies butt.</span>

sscherin 06-10-2011 11:31 AM

RE: Sig Koverall and Minwax Polycrylic
 
I sand with either a hard rubber or hevy paper (gasket material) pad on curves, sanding block for flats and the gasket material pad or by hand on open bays..
Watch the edges on open bays.. you'll sand through the fabric much quicker than you would think..

wet sanding makes the sand paper last much longer (that is if you are using a wet/dry paper)

Seams and patches completly disappear after the primer stage and first color coats.

This is where I am with the Citabria.. Every time I get ready to finish it I get sent off towork in some darn far away town..

http://images.rcuniverse.com/forum/u...77/ql35383.jpg

sensei 06-10-2011 11:35 AM

RE: Sig Koverall and Minwax Polycrylic
 
Why don't you go here and get a few of your answers. http://www.google.com/url?sa=t&sourc...0f9-_SIn89S9dg

Bob

Rcpilot 06-10-2011 11:39 AM

RE: Sig Koverall and Minwax Polycrylic
 
Since my structure is mostly open bays, I was planning to sand with a soft sponge and 400 grit.

I have 2 coats on now. Will start sanding when it's all dry.

AFTER I sand this 2nd coat, I'm planning to thin the minwax and hopefully that will make the brush marks disappear on the 3rd, 4th ... 5th.... coats. I might also switch to a foam brush. Don't want brush marks. I'll probably sand with 1000 grit between these final coats.

I'm not looking for perfect here. It's a Yard Bee and it's electric powered. Weight is a concern. It's a BIG Yard Bee and it has plenty of wing area, but I still don't want to weigh it down with too much filler and paint.


sscherin 06-10-2011 02:05 PM

RE: Sig Koverall and Minwax Polycrylic
 
I'd give the foam brush a shot.. it works well with the nelson paints. I didn't find brush marks to be an issue but I was using a nice art brush I got on clearence at a craft store..
the cheep coarse hair bushes do ted to make heavy brush marks.

I brushed the poly and primer coats on my stick. after wet sanding there were none left you could notice.

That one got a rattle can color coat and brushed on exterior urethane clear coat.

You won't believe the strength this covering adds to your airframe..

As an example.. I made an unintended full throttle touch and go in the long grass with my stick ( low pass gone to low)
The counter balance on the elevator caught the grass, sheared 3 robart pin hinges at the joint and snapped at the joiner dowel..

This was just a simple stab made from 1/4" sheet balsa.. I believe if it had been covered in plastic film it would have shattered the elevator rather then snapping the hinges.

It also pulled both wheels off the wire gear, bent the gear back at 45deg angle and sheared the hayes mount off leaving the flange bolted to the firewall..

the only damage to the fusealage was the elevator and a small spot on the corner of the firewall where the engine had turned back and hit it.

WacoNut 06-10-2011 02:14 PM

RE: Sig Koverall and Minwax Polycrylic
 
Another tip, I found that by thinning the PolyC about 15% with water made the coats go on much smoother. I can't stress enough to be careful sanding. When sanding over open bays you will sand thru the fabric in a hurry where it meets the edge of sheeting or cap strip. Sand very lightly after the 2nd coat and each coat after. You can give it a better sanding after the 4th or 5th coat.

Good LucK!!!
Anthony

Rcpilot 06-10-2011 07:35 PM

RE: Sig Koverall and Minwax Polycrylic
 
Thank you.

Not a lot of work today. Got stalled.

Sanding the 2nd coat now.

pacoflyer 06-11-2011 01:56 AM

RE: Sig Koverall and Minwax Polycrylic
 
Thanks Charles
I was just wondering if you or anyone else have ever used the water base stuff with the Stitts. I'll probably just "stick" with using the Poly Tack

paul

ARUP 06-11-2011 04:40 AM

RE: Sig Koverall and Minwax Polycrylic
 
Hi RCPilot- just saw this thread. A foam brush will spread the Polycrylic better than a brush. A brush tends to push the Polycrylic thru the covering and cause 'pooling'. Ask me how I know! A light sanding between coats works well. 3-4 coats should be sufficient to seal but not fill the weave.

Rcpilot 06-11-2011 06:38 PM

RE: Sig Koverall and Minwax Polycrylic
 
1 Attachment(s)
Initially I put 2 coats of polycrylic on the fabric and then sanded with 400. I didn't go crazy with the sanding. I just worked on a couple runs and a few spots where a piece of dust or lent landed in the paint.

Then I thinned the polycrylic with denatured alcohol. I had about 1/2 a pint can left at that point, so I only added about 1 tablespoon of the alcohol to thin. It was quite a bit thinner. Brush strokes disappeared. I kept on using the same brush throughout this entire phase of the project. I just washed it in warm water each night with a little liquid hand soap. During the day when I was working with the brush I stored it in a jar of water.

2 more coats of thinned and sanded with 600 grit between coats. It's FAR from perfect.

Shot thin layer of white primer. Krylon paint. Sanded the primer and shot another very thin layer. Sanded with 600 grit. Then shot white Krylon satin gloss. I had it lying around and it was a new can that matched the same brand of primer I sprayed on earlier, so I used it. I shot the first coat and let it dry about 4hrs. Sanded a few spots with 1000 grit and shot it again.

The clear strips on the bottom of the wing will get a few coats of krylon clear. I'm going to put an LED light kit inside the fuselage. The angle of the side windows will allow the light to shine up inside the wing...... I hope.

Pretty much done with the wing. Couple coats of clear and a little more sanding. I am going to move forward with the fuse and tail surfaces. Will use same techniques. Let me know if you want to see pics of that.

huck1199 06-11-2011 06:46 PM

RE: Sig Koverall and Minwax Polycrylic
 
Looks very nice.  Why did you thin with alcohol instead of water? 

Rcpilot 06-11-2011 07:19 PM

RE: Sig Koverall and Minwax Polycrylic
 


ORIGINAL: huck1199

Looks very nice. Why did you thin with alcohol instead of water?

Thanks.

Dunno. Figured it would evaporate out. Next time thin with water? [sm=confused.gif]

It ain't pretty from up close. It's got little bubbles all over in the finish. I made the mistake of shaking the minwax polycrylic. It was full of micro-bubbles and they didn't brush out of those first 2 layers.

STIR your polycrylic.

DO NOT shake it.

It'll work. I'm learning a new technique and it's fun. I wish I had learned to use fabric a long time ago. Love the way the seams disappear. A buddy came over and took a look. He said it all feels smooth and looks great.

huck1199 06-11-2011 09:03 PM

RE: Sig Koverall and Minwax Polycrylic
 
If the alcohol works then why change.  Like you said; it may dry faster.  The reason I asked was I never heard of using alcohol before and thought you might have a new technique.  If it works, thats great, I may try it. I really like using fabric. I did a beaver and I am now using on my Spacewalker - see my thread - http://www.rcuniverse.com/forum/m_10..._7/key_/tm.htm

Rcpilot 06-11-2011 10:02 PM

RE: Sig Koverall and Minwax Polycrylic
 
1 Attachment(s)
Got off in a little bit different direction but don't worry, it's along the same lines as the Koverall. ;)

I'm using minwax polycrylic and 0.6 oz cloth on the horizontal stab and elevator. Painted one layer of poly onto the 3/16" slab balsa. Let it tack up for a few hours. Sanded real quick with 400 and then 600. Sanded easy. Knocked the fuzzy spots off and hit it with the tack cloth. Placed the fiberglass cloth on and brushed it down with a coat of polycrylic. I'm letting it tack up for 30-40min and then hit the edges with the covering iron set to 1/3 power. Planning to sand and fill this. One coat of full strength poly out of the can. Sand it. Then thinned poly for one layer and sand it. Prime and paint.

Bottom of the stab before cutting off excess.

After cutting off and sealing edges with iron.

Rcpilot 06-12-2011 01:27 AM

RE: Sig Koverall and Minwax Polycrylic
 
1 Attachment(s)
Stab is ready for paint. Top of the elevator is still drying.

bps 06-12-2011 03:02 AM

RE: Sig Koverall and Minwax Polycrylic
 
I use a latex filler and glue from Michaels Craft Stores called Modge Podge. I use a latex conditioner Floetrol to thin the MP. Seal the framework first and a light sanding followed by another sealing coat and light sanding. Then using the MP brushed around the edges of the Koveral attatch the fabric just like you would using dope. I use the same MP thinned just a bit more to fill the weave of the fabric after shrinking and trimming. Latex paint and then a top coat. Very easy and does not stink!

WacoNut 06-12-2011 04:24 AM

RE: Sig Koverall and Minwax Polycrylic
 
If you get bubbles in the PolyC then you need to make sure your are sanding away the top of the bubbles before getting to your final coats. You can actually use these bubbles to gauge how much you are sanding. I found that by thinning by 15% and using the foam brush I did not get near as many bubbles to deal with.
Your wing looks pretty good and you will only get better with each piece you do.
Later!!
Anthony

Rcpilot 06-12-2011 09:29 AM

RE: Sig Koverall and Minwax Polycrylic
 

ORIGINAL: WacoNut

If you get bubbles in the PolyC then you need to make sure your are sanding away the top of the bubbles before getting to your final coats. You can actually use these bubbles to gauge how much you are sanding. I found that by thinning by 15% and using the foam brush I did not get near as many bubbles to deal with.

I shook the minwax can at Lowes - got bubbles in the liquid. I realize a better sanding job would have got rid of the bubbless. But I don't have a whole lot of sand paper at this time. I'm using cut off scraps from past projects - leftover sheets. Elbows and wrists are sore from sanding with worn out paper. If I wanted to spend $10-$12 on a package of quality sand paper and a couple foam brushes, the bubbles would not be there. I'm just trying to keep it cheap and learn a new technique for right now. The finer details will come when I'm working on a serious project with a bigger budget.

Thank you for the compliment.



DUCO 06-12-2011 11:15 AM

RE: Sig Koverall and Minwax Polycrylic
 


ORIGINAL: WacoNut

I have used Sig Koverall and PolyCrylic on several planes. The results are well worth the effort. I found 4-5 coats of the polyc gives me the results I am looking for. My 33% Waco is covered in this manner and is painted with latex paint.
It is nice not having to worry about the covering starting to wrinkle over time of the edges lifting.
Later!!
Anthony
I just luv ole school ways!

Lowvoltage 06-12-2011 05:55 PM

RE: Sig Koverall and Minwax Polycrylic
 
1 Attachment(s)
1. I glued the koverall to the trailing edge of the wing and wrapped the fabric underneath and around the leading edge and all the way back to the trailing edge again.
2. I only applied adhesive (polytack) to the trailing edge and the wing tips after Ihad the cloth where Iwanted it.
3. I didn't stick the fabric to the ribs or spars until the fabric was heated twice.
4. Then I used a 1/2" wide chipping brush to put policrylic on all wood parts that are covered with fabric.
5. After that, I started putting the policrylic on with a sponge brush.
6. It's obvious that koverall and policrylic can make you look very good almost any way you put it on!

This is my first koverall job
Joe


Rcpilot 06-12-2011 07:19 PM

RE: Sig Koverall and Minwax Polycrylic
 
Looks awesome Joe. Very nice job.


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