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Cheap balsa filler, and WBPU.


Tim Hooper
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Just thought I'd share a couple of alternatives that I've been using for years!

Both are available from DIY outlets such as Homebase, and work out a lot cheaper than the model-specific varieties.

Lightweight filler - excellent for use on balsa.

**LINK**

Ronseal Diamond floor varnish. Excellent for giving a hard finish to your 'glassed' model. Maybe not as tough as 2-pack, but I've used it several times with success. Not much smell or mess, and your brush can be rinsed clean with water. Available in smaller tins too.

**LINK**

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I use the same stuff. The biggest problem I have is that the varnish sticks the lids on better than any adhesive. I now transfer it to plastic milk bottles (after emptying).

I have used other makes of WBV, as well other lightweight fillers. All seem much the same to me,

The only WBV I have found to be different was I think called "Eski", so hard, it was a pain., also tended to crack, being brittle, on the structures we use.

I also use the WBV with glass cloth, works really well. At least as well as laminating epoxy resin, although more coats are required. Importantly the weight does not build up to much.

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A word of caution with regard to lightweight fillers - some of them use a styrene type of bulking agent. Not a problem unless you paint the model with something like Solarlac, when your nicely filled seams suddenly reappear as the filler melts away. I found this out on my Skybolt, luckily it was on the rear underside where it doesn't show much.

But I know it's flawed...

Edited By Bob Cotsford on 04/02/2013 22:18:21

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It probably is worth emphasising Andy's point, the filler to use, who ever's brand it is, is typically sold as "light weight filler". As has been stated, the containers feel as if they are empty, it is that lightweight.

The other issue is that the filler is very friable. So any large volume is liable to easily fall out. To combat this, I fill the bulk with the void with the filler, previously mixed with a little PVA. Then immediately skim with a light topping of straight filler, which can easily be sanded. That is when the whole lot has dried. This technique will be strange to TH, only skilled butchers. need bother.

As to being dissolved by solvent, I am not sure. I think I used it on my Guillows Thunderbolt, which was subsequently covered with tissue and dope.

I generally find that when covering with glass cloth, the WBV, stabilises the lightweight filler, making it tough.

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Hi I use the lightweight filler and WBPU from Wilkinsons. £3.95 for 500ml of filler and around £6 for the wbpu 750ml that sets in 1 hour. For a great sanding sealer for foam try thinning the lightweight filler with wbpu so its like a creamy yoghurt. It brushes on and sands off nicely. Really helps fill the weave if glass has been used. Ady

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It may appear to be pedantic are they varnishes we are using, which I thought that Diamond Hard by Ronseal was a varnish, rather than a urethane or Polyurethane.

I have had a telephone conversation with a technician at Ronseal, that went into the differences as to why the varnish is not as hard, due to the solvent being a water, whereas the polyurethane product had a solvent, which with increasing environmental legislation, limited the solvents available. But to be honest I did not remember much of the conservation, mainly as i did not properly comprehend the science.

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WBPU = Water Based Polyeurethane Varnish.

Proof against glow fuel.... Errr that depends on who you listen to and what you buy. PolyC seems to be a WBPU type product with an adhesive added and that claims to be glow fuel proof. In practice I would say that if you clean an airframe down after each use itis OK, but that it is not as fuel proof as fuel proofer.

If you are wanting to glass an airframe, PolyC is very good, and does seem to contain an adhesive which does a better job of glueing the cloth to the airframe. It is no more expensive than the products mentioned and will spray [with care] over a coat of sprayed emulsion to provide adequate fuel proofing. It is also a silk finish rather than gloss.

Some of this is is glassed with poly C, [some with another product] sprayed with emulsion paint thinned with screen wash, and then sprayed with a coat of PolyC

And this is the same...

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This may sound weird and off-the -wall but One Day , I was scratching around for some lightweight filler at 10.30 pm !!! Didnt have any of course as I had run out . Had plenty of White PVA liquid adhesive --- so I raided the Cook.s domain ( She was safely at work !!! and came across a container of Soya Powder which mixes with anything .

Taking an empty clean butter container I then made an ad hoc mix until a creamy paste obtained .

Applied it with spatula and smoothed it over and left it until next am . Buffed it off and then proceeded

The excess mixture kept well in the sealed Container and was useable much later -- 2 Months without going hard . Even experimented further by re - mixing same kind of admixture to it .

No Problem -- its light and cheap .

The One Downside I found was the smell of the residue ---

Someone out there must produce an idea of ADDING something which will either kill OR better still make it smell like an airfreshener.!!!!!!!!!!!!!!!!!

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