Chris Bacon wrote:
On 14/06/2021 18:21, Paul wrote:
Chris Bacon wrote:
Ronseal wood filler seems to be styrene and talc, mixed, with
hardener you add and mix.

Sounds awfully like car body filler, which is lots cheaper. Is it the
same, or different (how)?


polyester resin and "cream hardener"

Not the same.

The big book of chemicals has one million compounds
in it. And that's just scratching the surface, so to speak.
You could easily fill a store with items, where no two
were the same.

As for the body filler idea, beware. My repair of an exterior
wood window frame, the body filler shrinks. And it shrinks, even
though it has several coats of paint over top. The issue is,
filler used on a car, you are only filling imperfections
and the amount used is not very thick. Whereas when replacing
a section of rotted wood, you might have a great thickness of
body filler, and that's when you'll notice the shrinkage after
five to ten years.

What the hell's "cream hardener"? Details, please, details.

Car body filler generally containd styrene and an inert substance,
normally talc, calcium carbonate or whatnot. So does Ronseal wood filler.

I've used car body filler to fill holes in timber before. I have not
known it to shrink Like the Ronseal stuff, it stays the same, but the
timber itself can change.

What filler did you use? Car body filler can certainly be used in thick
layers. Maybe the "imperfections" you refer to are filled with
"stopper", not "filler"?

https://en.wikipedia.org/wiki/Polyester_resin

"This compound is known as the catalyst within the industry,
but initiator is a more appropriate term. Transition metal salts
are usually added as a catalyst for the chain-growth crosslinking
reaction, and in the industry this type of additive is known as
a promoter; the promoter is generally understood to lower the
bond dissociation energy of the radical initiator. Cobalt salts
are the most common type of promoter used. Common radical initiators
used are organic peroxides such as benzoyl peroxide or
methyl ethyl ketone peroxide."

They show it being used for repairs here.

https://www.3m.com/3M/en_US/bondo-us/

There are choices.

https://www.autobodytoolmart.com/body-filler-howto

Standard - lightweight putty that cures in approximately 20-25
minutes. Standard grade fillers are typically only
used on small scratches and minor dents such as hair damage.

Medium - also known as a fiberglass filler, medium grade fillers
are useful for tiny holes or tears in either metal or fiberglass.

Premium or aluminum filler, is called such due to microscopic
aluminum particles in the consistency of the mix. The
benefit of using this expensive filler for larger repairs
and dents is that it doesn't shrink, is easier to sand,
and is stronger than other fillers.

I don't know if there were quite that many choices
at the hardware store in the auto body section.

Body filler is its own culture.

https://www.hotrodders.com/threads/m...e-honey.51195/

"fiberglass resin is usually catalyzed with mekp
while body filler is catalyzed with benzoyl peroxide."

Paul