Poly-C opinion?

[Matt Carlton]

Hello all, 

Has anyone used "Poly-C" as below? 

 

Poly C

 

If so, what did you think? Considering it as a cheaper and healthier alternative to epoxy for a glassed finish, but wondered how well it takes paint. My idea would be to use something like Krylon Fusion from a rattle can over it, but wonder if it would react weirdly? 

 

Any experiences are gratefully received!! 

 

Cheers

 

Matt

[Frank Skilbeck]

I used it to cover a model fuselage last year, Poly C and Nylon, it takes more coats than epoxy but goes on well and dries quick. I sprayed it with cheap rattle cans, it went OK. On the same model I glassed the wings and couldn't detect much difference in spraying either surface.

[Murat Kece 1]

Hi Matt

I used it a couple of times on my gliders. It works very well. It is easy to apply and clean. It takes 6-8  coats with light wet/dry sanding in between to fully cover/fill the fiber cloth but at the end you get a good finish. It takes the paint well too. I used the Plastikote aerosol spray paint from a can. See the example below.

 

 

Edited April 28, 2021 by Murat Kece 1

[Kevin Fairgrieve]

Sprayed with rattle can grey primer.

 

Covered in lightweight glass cloth and PolyC.

Takes a lot of coats.

I also usually use it on engine bays, but it does take a long time to fully harden in my experience.

 

[Ace]

 

The application is directly onto a 68" white foam wing with inset spars top & bottom and a ply brace as opposed to usual balsa/veneer sheeting first? 

So in order of ding resistance thoughts on my assumptions?

Epoxy/glass

Poly C/glass

Poly C/brown paper

PVA/brown paper

Film

 

Has anyone tried brown paper applied with Poly C rather than the traditional PVA? 

Does it soak and stick and is it tougher than PVA?

 

I have used PVA/brown paper directly on blue foam 1/12 scale combat models but their expected life was short and would dent if handled roughly.

[MattyB]

Poly C is fine, but as others say it does require a of coats and time to get a good finish. I'm not honestly sure it's any better than any standard polyurethane varnish though - I've used clear Ronseal Diamond Hard for small repairs with good success, and it's a fair bit cheaper.

[Nigel R]

2 hours ago, Kevin Fairgrieve said:

Sprayed with rattle can grey primer.

 

Covered in lightweight glass cloth and PolyC.

Takes a lot of coats.

I also usually use it on engine bays, but it does take a long time to fully harden in my experience.

 

 

Hi Kevin

 

Which rattle cans?

 

I guess, a coat or two of poly-C to fuel proof, after the colour?

[Mike T]

I used it once directly on a balsa fuselage.  Following the instructions not to sand until the final (about 8th) coat, I ended up with a very bumpy fuselage, as the grain-swelling induced by the first coat had been faithfully reproduced and magnified by the succeeding ones!

So TOP TIP - coat balsa with dope and rub down to a sealed finish before applying Poly-C (or any WBP)

[Alan Gorham_]

It strikes me that any finishing system where you have to start using dope prior to using the other system is flawed and you may as well carry on using dope.

[James Green2]

1 hour ago, MattyB said:

Poly C is fine, but as others say it does require a of coats and time to get a good finish. I'm not honestly sure it's any better than any standard polyurethane varnish though - I've used clear Ronseal Diamond Hard for small repairs with good success, and it's a fair bit cheaper.

Absolutely and if you use brown paper you don't have a weave to fill so requires fewer coats. 

[Matt Carlton]

Interesting responses, thankyou everyone. One thing strikes me is that rather than using lots of coats of Poly-C, would it be feasible to use a high build primer like this:

 

Krylon 2in1 primer

 

To fill the weave and provide a surface to spray a top coat onto. Might be heavy? Not sure. 

 

 

[Andy Stephenson]

I have used 1000 grade lining paper on EPS foam with good results but I have always filmed it afterwards. Next time I may try attaching it with hard glaze as the PVA I have been using tends to shrink too much. I suppose it depends on the water content of the of what you are using.

[Mike T]

42 minutes ago, Alan Gorham_ said:

It strikes me that any finishing system where you have to start using dope prior to using the other system is flawed and you may as well carry on using dope.

With hindsight (or should that be fore-knowledge) I should have dampened the fus. to raise the grain then lightly sanded with new, sharp sandpapers to knock off the high spots without compressing the grain.  I'd bet it would still ripple slightly though.

I like dope - you know exactly where you are with it. OTOH I dislike epoxy resin.  You only have to look at the bottles and it's all over your hands! ?

[Mike T]

11 minutes ago, Andy Stephenson said:

I have used 1000 grade lining paper on EPS foam with good results but I have always filmed it afterwards. Next time I may try attaching it with hard glaze as the PVA I have been using tends to shrink too much. I suppose it depends on the water content of the of what you are using.

It's great for drawing on too - takes a pencil really well! But what is 'hard glaze', Andy?

[Andy Stephenson]

Mike,

Hard Glaze is one of the newer water based varnishes that come from Dulux and Ronseal, It's like Deluxe Materials Eze Kote but much cheaper although you have to buy a minimum of 1 litre.

 

It can be used instead of epoxy for finishing a glass covering etc.

[Murat Kece 1]

Pol-C and varnishes mentioned above are the same thing! They are water based varnishes..

[Glenn Philbrick]

I've used poly c for many models, both Brown paper covered and glassed. Often mix poly c with lightweight filler to a cream like consistency to fill the weave. I believe some call it spakle, also good for filling polystyrene models.

[Kevin Fairgrieve]

8 hours ago, Nigel R said:

 

Hi Kevin

 

Which rattle cans?

 

I guess, a coat or two of poly-C to fuel proof, after the colour?

Just a high build grey primer from the local car repair shop.

 

A while ago now but if I am correct it was about 3 coats of PolyC, rubbed down lightly between coats then 2 coats of primer again rubbed down. 

Final coat of primer then more PolyC. Probably eight or nine coats in total.

 

To be honest it was a lot of work and I think it came out on the heavy side.

Edited April 28, 2021 by Kevin Fairgrieve

[ron evans]

On the model in my avatar I used glass and the filler/poly mix on the foam fuz.

The balsa sheet wing had a couple of coats of the mix, rubbed down in between. The surface is a bit chalky so a final coat of poly before spraying with a rattle can.

Ron

[Don Fry]

34 minutes ago, ron evans said:

On the model in my avatar I used glass and the filler/poly mix on the foam fuz.

The balsa sheet wing had a couple of coats of the mix, rubbed down in between. The surface is a bit chalky so a final coat of poly before spraying with a rattle can.

Ron

did the filler/poly mix go brittle with time Ron? I’m asking because, as an epoxy user, it’s a shock every time you buy some. I don’t much care if it’s not fuel proof, I know it is not, but I would care if it cracks, and breaks, my 2 pack top layer. 

[ron evans]

One of my models with an epp fuz is finished this way, the glass is applied with neat poly, rough edges sanded off then a few coats of the mix, lightly sanded with a coat of poly before paint.

The epp is quite flexible and will give if gripped too hard when hand launched. It's six years old and no cracks at all.

I use Wilko poly.

[Don Fry]

Cheers Ron, quick, cheap, light. What’s not to like.