On Tue, 14 Apr 2009 10:11:53 +0100, IanM
wrote:

(PeteCresswell) wrote:
Most of my glass work is small ding patches.

Mixing up, say, an ounce or less of resin and getting the
resin/catalyst ratio right (especially with epoxy) escapes me....
so I waste a lot of resin.

Anybody got a system?

For polyester, I'd think it would be counting drops of catalyst
into some amount of resin that's easy to pre-measure.... like
maybe a rounded tablespoonful or some standard-sized very small
paper cupful.

For epoxy, the hardener I have doesn't drip so well...


Anybody got a system?
'Blue Gee' do a general purpose epoxy system with fast and slow
hardeners and a 2:1 mix ratio. Their small packs come in bottles with
built in measures, 10ml fixed for the resin and 10ml calibrated in 1ml
units for the hardener. This allows a minimum mix of 15ml.
If you use little calibrated measures similar to those supplied with
cough syrups and similar medicines, you can mix down to three times the
unit calibration for a 2:1 resin but only six times for a 5:1 system.
The trick is to MIX IN THE MEASURE and measure the least viscous
component first then drip in the other one on top. As the measures tend
to be tapered and are made of a waxy plastic, set leftovers can easily
be popped out of the measure so you can reuse it.

Polyester resins are a lot easier as the mix ratio is far less critical.
Calibrate your hardener dropper bottle using a clean measure and your
preferred hardener. Calculate the number of drops for the correct mix
ratio in 10ml of resin IIRC for Blue-Gee it's three drops in 10ml.

Measure the resin in a clean measure, pre-wetted with resin and drained
for one minute. Always drain your measure for the same time after
measuring. This compensates for the resin stuck to the sides. Decant
into a polypropylene disposable plastic cup and drip in the hardener
while mixing thoroughly. I like the small disposable chopsticks as
supplied in Sushi boxes for mixing sticks as the shape lets you get
right down into the bottom corner and avoid unmixed resin lingering
there to **** up your result.

I'd love to have a digital scale with 0.1g resolution, but can't justify
the expense or storage space on board.

If its non-critical bulk and surface repair, 'Plastic Padding' do a
polyester resin product in tubes. There is a thickened glassfibre filled
resin suitable for minor bulk structural repairs not requiring too much
tensile strength and a thickened white gelcoat paste. You just measure
equal lengths from both tubes. Minimum mix quantity is about 1ml.

I have been small tubes of epoxy for decades. They all have been
50/50. Two same sized puddles on a piece of paper and mix with a
spatula, a popsicle stick works. Reloaders scales are accurate to a
tenth of a grain, or a hundredth of a gram, flip a switch. Put the
paper on the pan. Scale fits in a shirt pocket.

Casady