Oxidised Fibreglass

[Underwood]

I just removed much of the vinyl graphics on the Nynja I bought and as they have been on there for about 12 years then there is a noticable difference between  where the vinyl has kept the fibreglass nice and white to the slight yellowing of the exposed areas.

I did think perhaps T-Cut and an orbital polisher but the boat forums all say not to use that but something called starbrite.

But I'm not sure how similar the very thin fibreglass on a Nynja is to the boat stuff (is it the same but just thinner?

 

 

Has anyone tackled this on their Nynja or similar airframe?.

 

[turboplanner]

47 minutes ago, Underwood said:

I just removed much of the vinyl graphics on the Nynja I bought and as they have been on there for about 12 years then there is a noticable difference between  where the vinyl has kept the fibreglass nice and white to the slight yellowing of the exposed areas.

I did think perhaps T-Cut and an orbital polisher but the boat forums all say not to use that but something called starbrite.

But I'm not sure how similar the very thin fibreglass on a Nynja is to the boat stuff (is it the same but just thinner?

 

 

Has anyone tackled this on their Nynja or similar airframe?.

 

The material is Fibreglass Reinforced Plastic.

The Fibreglass is the glass strands which act like steel mesh in concrete.

The "plastic" is a Thermosetting Resin, usually Polyester Resin.

There are hundreds of different makes and types of polyester resin.

The outer or visible surface which is painted onto the mould is also a resin pigmented to the desired colour. This is called a Gel Coat.

 

In your case it sounds like there might be some oxidising of the gel coat.

 

I would talk to the Nynja manufacturer to establish whether Starbright gel coat restorer would be suitable for the materials used in the Nynja laminate to ensure you don't get a nice white surface but then have to replace a weakened panel.

 

In boats and vehicles and other products, painting, spraying a new gel coat then laboriously cutting out the high spots to get a moulded finish are options, but add too much weight for a small aircraft like this.

 

If the oxidation is through the gel coat and into the laminate there will be structural deterioration, so replacing the panel my be the cheapest option.

 

 

 

 

 

 

 

 

 

 

 

 

Edited Friday at 07:31 PM by turboplanner

[FlyBoy1960]

"The "plastic" is a Thermosetting Resin, usually Polyester Resin."

 

It could also be epoxy resin, Polyester is so last century.   Need to follow your good advise and check with the manufacturer!

[skippydiesel]

19 minutes ago, FlyBoy1960 said:

"The "plastic" is a Thermosetting Resin, usually Polyester Resin."

 

It could also be epoxy resin, Polyester is so last century.   Need to follow your good advise and check with the manufacturer!

That's interesting - I was advised to make my cowling out of polyester,  it's supposed to have greater heat tolerance than epoxy. I know very little about composites, so I just followed the advice of my local composite materials supplier.😈

[turboplanner]

Epoxy resin is most commonly used as an adhesive.

[Red]

On 24/01/2025 at 9:36 PM, FlyBoy1960 said:

"The "plastic" is a Thermosetting Resin, usually Polyester Resin."

 

It could also be epoxy resin, Polyester is so last century.   Need to follow your good advise and check with the manufacturer!

Yes most glass sailplanes use epoxy resin, I'm not at all sure about the Panels of a Skyranger Paul Dewhurst at Flylight is probably the person to ask

[BrendAn]

On 25/01/2025 at 8:58 AM, skippydiesel said:

That's interesting - I was advised to make my cowling out of polyester,  it's supposed to have greater heat tolerance than epoxy. I know very little about composites, so I just followed the advice of my local composite materials supplier.😈

its cleaner and quicker and cheaper.   epoxy is excellent for strength.   even if the skyranger is epoxy it probably has some sort of poly gelcoat.  

any marine gelcoat restorer will do the trick. i have brought a couple of boats up like new by rubbing oil onto them. restorers probably do something similar.

[Blueadventures]

I give mine a hand cut / polish / wax with a good quality Meaguires product about twice a year; just keep off any decal areas.  Starbrite is more like a water stain remover.  I'd try the hand polish on an under surface; it should work and most likely you will always notice a different shade where the decals were.  Paul or Mark Hilton will have some ideas especially Mark as they restore and repair a lot.

[Underwood]

Thanks for replies, I tried the Starbrite stuff that the boast forums recommend and its expensive rubbish, made no difference whatsoever.

I think I'll try good old T-cut on an small area and see what that does

 

[turboplanner]

25 minutes ago, Underwood said:

Thanks for replies, I tried the Starbrite stuff that the boast forums recommend and its expensive rubbish, made no difference whatsoever.

I think I'll try good old T-cut on an small area and see what that does

 

There's nothing wrong with Starbrite, probably the issue is not translated just by written word.

It could be that the oxidation which can be cut up at the surface has left the gel coat porous in which case you have to sand the gel coat off and apply new gel coat, and it could also be that the oxidation is into the resin, so maybe take a panel to an expert.

[skippydiesel]

One of my local flight schools uses exclusively Jabiru aircraft - all parked outside, most for very many years now. Only one or two with some very basic shade. The external surfaces are no longer shiny but appear to be in good order. 

 

I am impressed by their weather resistance.

 

What sort of composite are Jabs made of ??😈

[facthunter]

Fibre glass I believe. Plenty built them themselves. A few gained a bit of weight. ( the PLANES). They also survive Prangs well compared to a lot of other stuff and CAN Nearly always BE REPAIRED.  Nev

[turboplanner]

It's the gelcoat and resin that oxidise, not the glass fibre.

[440032]

Here's a thought.

Ask the manufacturer for some restoration advice - Leisurebuild in Bundaberg.

Aircraft | Leisure Build Pty Ltd

 

[BrendAn]

its a bit of oxidising for christs sake.  polish with one the many restorers avialable at any auto parts store or boat shop and wax it when your finished. 

[PureCaboose]

I am addressing this issue with my J160. It spent a few years outside on the handstand, with a pumpkin head cover, at least. The wings, tailplane, etc., were not covered by the pumpkin head cover; they were powdery to the touch and felt rough. The bugs take time to clean off after flight.

 

Over the last few days, I have been cleaning and cutting with Septone Cut and Prepare (Step 1) and following up with Septone Polish and Protect (Step 2). The areas I have done so far feel smooth and clean; the bug guts wipe off with a little spray cleaner, and water easily beads and runs off.

 

Being a wax, it can be removed for repairs when needed. I did a day of work by hand but struggled to use my arms the next day, so I upgraded to an 18v battery polishing/buffer machine, which is perfect. Once I have done the whole airframe (excluding windows), this will be an every 6 months maintenance task for me, especially as she sits in a hangar now and is no longer exposed to the elements, except when she flies.

 

[turboplanner]

A few scary things being tossed around here, just be careful where the laminate is structural or subject to wind pressure.

It sounds like the oxidation on this aircraft is deeper, than a polish treatment can handle.

 

FRP is Fibreglass Reinforced Plastic. (Plastic reinforced by glass fibres)

The plastic is structural augmented by the fibreglass.

 

The gel coat is not structural so you can polish or buff that away, but you need to put a new layer of gel coat on to stop the raw material picking up water and rotting.

 

However as soon as you start to lose the gel coat colour you're grinding your structure away so that's the time to look at a new panel.

 

In some cases the oxidation will already be deep enough to be powdering the FRP; if you have FRP skills, you can grind it down clear of the oxidation, then laminate back up to the original thickness or a little more but then there's a lot of sanding to get it looking like the original, as well as the sanding of the gel coat.

 

If you want to see this in action, look at a few boat transoms. The area oxidises, water gets in and rots the transom beam and the next thing you know the motor's in your lap.

 

 

[skippydiesel]

For what it's worth:

 

I have always shied away from using any cutting compound on paint/gelcoat.

Seems to me that the benefit (removing some esthetic blemish) is as short lived as the polish containing the abrasive or polishing applied after.

I also feel that the damage to the paint or gelcoat, may eventually lead to other problems, "down the track".

From my jaded perspective, this is a technique/system, much loved by second hand car dealers (& the like) to present their, suspect offering, in the best light.

😈

[facthunter]

It's an accepted practice to remove Old oxidised and faded paint to restore a good surface. OF Course there's a limit to the process when you wear through the colour. Waxes preserve the surface . You don't have to "Cut"it ever time you do it. Some washing detergents leave some wax on the surface.. The sun's rays are hard on rubber Plastics Paint  wood and your skin.  The plane should be out of the weather preferably. Dust contains chemicals too. .   IF you don't look after stuff it will rapidly degrade especially IF you are near the sea or an Industrial atmosphere.

[BrendAn]

In the boating world gelcoat is kept polished . Eventually it will wear thin, then it's gets a gelcoat respray or the preferred method these days is paint in 2 Pac epoxy. Lighter than gelcoat and long lasting.

I thought jabirus were painted in Matterhorn white 2 Pac instead of gelcoat.. someone will correct me .