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Low temperature filling

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paul330

Well Known Member
I am struggling to finish my RV-10 canopy and doors and am up against a deadline - she is booked in for paint in 10 days.

Part of my problem is that I am in an unheated hangar in England in the Spring. Day time temperatures are around 15 (or 60 in US money) and it is generally taking 2 days for the epoxy filler to harden enough to sand.

I am making the filler using 2 part epoxy and glass balls. The epoxy/hardener ratio is 2:1. Here's my question - since this is non-structural filler, would it be acceptable to increase the ratio of hardener (say 3:2) and would that actually make it harden quicker?
 
I feel your frustration working with epoxy and glass balloons. It is slow to cure and much too hard for a filler. But in the old days that was the best product available.

A local body shop owner is doing some final finish work for me around the wind screen. He uses Everglass. At 60F it cures in about a half hour and sands easy. Great stuff, if ever I do another canonpy I will use it instead of epoxy.

http://www.evercoat.com/productDetail.aspx?pID=36
 
paul330 said:
I am struggling to finish my RV-10 canopy and doors and am up against a deadline - she is booked in for paint in 10 days.

Part of my problem is that I am in an unheated hangar in England in the Spring. Day time temperatures are around 15 (or 60 in US money) and it is generally taking 2 days for the epoxy filler to harden enough to sand.

I am making the filler using 2 part epoxy and glass balls. The epoxy/hardener ratio is 2:1. Here's my question - since this is non-structural filler, would it be acceptable to increase the ratio of hardener (say 3:2) and would that actually make it harden quicker?
Click to expand...

Epoxy must always be mixed in the exact ratio as specified by the manufacturer, otherwise it may not cure. With some brands, you can get a different hardener ('fast hardener') to accerate the cure.

The suggestion here to use an Evercoat filler are fine as long as you are not filling large voids where the strength of epoxy is required.
 
Even using Evercoat, you may need some thermal assistance. I would use a heat gun to warm the area to ensure full curing. You will see a gummy skin on the surface that quickly fouls sand paper if it is not cured enough. I won't say fully because it will get rock hard later. There is a sweet spot where it is hard enough to sand and not shrink further. This can be facilitated with heat.

Good luck!
 
paul330 said:
I am struggling to finish my RV-10 canopy and doors and am up against a deadline - she is booked in for paint in 10 days.

Part of my problem is that I am in an unheated hangar in England in the Spring. Day time temperatures are around 15 (or 60 in US money) and it is generally taking 2 days for the epoxy filler to harden enough to sand.

I am making the filler using 2 part epoxy and glass balls. The epoxy/hardener ratio is 2:1. Here's my question - since this is non-structural filler, would it be acceptable to increase the ratio of hardener (say 3:2) and would that actually make it harden quicker?
Click to expand...

Don't change the ratios recommended by the manufacture, as previous pointed out. But, can you tent the area with a blanket or two and some light bulbs or a small heater? I've done this to work on areas in the winter with excellent results.
 
Thanks for the tips.

I assumed that most automotive type fillers are polyester resin based. In the manual, VANS specifically say not to use a polyester based resin/filler on the canopy/cowl etc.

I'm not doing anything structural - basically building up/sanding at the canopy/door interface to get the right fit. Seem to have been doing it since Pontius was a pilot......

Thoughts?
 
And.......

All the small filling, blending jobs I did with standard automotive bondo.

Yes it's polyester, it goes rock hard in 20 mins and sands beautifully.

Get a pad of onion skins to mix them on - much cleaner.

Your local trade auto paint supplier will have them, if you are stuck, email me and I will post some.

M
 
Thanks everyone - seems polyester bondo is fine. Will visit Halfords on my way to the airfield.

Did I mention that I HATE fiberglass? :mad:
 
I'm always amused to hear about the wonders of cheap polyester filler on a 100K airplane....when most folks go to great lengths to avoid even a whiff of it on a used car.

Not sure what epoxy you're using (2:1 ratio?), but West with 205 hardener cures down to 40F.

If you've been adding filler, then sanding, then adding more filler, then sanding, well, you're doing it wrong. Always try to apply an excess of filler and cut/sand one time. Doing so means you have a consistent sanding hardness; no soft and hard spots to cause a wavy surface.

Filling isn't fiberglass work, and good fiberglass work doesn't need much fill.
 
I have been doing several things - laying up around the windows, covering rivets and blending to the aluminium bodywork and adjusting the door fit. Clearly, I'm not that good with fiberglass because I have been at it for some considerable time. However, I am almost there.

I am using a stock epoxy resin from a UK supplier which specializes in boats. In hindsight, I should probably have opted for something like West but it didn't seem worth paying a large premium for non-structural work.

The work on the fairings has been fine - it's just the canopy/doors that have given me grief!
 
Well, I got to the limit of my ability and left the final touches to the experts. It's back from the paint shop and I have to say they have done a FANTASTIC job. It appears that all the filling and rubbing down paid off in the end with the fiberglass/aluminium boundaries near invisible.

Plain white at the moment; graphics arrive mid-week. Photos then!

No more rubbing down - yeah :D
 
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