crystal clear polyester

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#1

hello ppl. i got myself a kg of totally clear polyester resin, thought i’d use it for cheapo overlays. It has one irregularity though. while polyester uses 2% catalyst, this one uses 0,3%!!

thats hard to measure, especially when i mix 30-40 gr for overlaying a small part. i dropped about 10 drops in 50gr and it worked ok, gelling on the manufacturer’s time.

does anybody know a good way to measure such small quantities?

also i heard that totally clear polyesters are not as strong as the normal ones…is that true?

#2

Get yourself a 100 gram digital scale should help. Or even a triple beam scale

#3

Very strange. That seems like an awfully small percentage. Even on a gram scale that would be difficult to measure properly.

#4

The clear polyester casting resin I have used was much softer when cured compared to tooling polyester resin i used.

I’m not sure if what you bought is clear casting resin though:confused:

It should be fine for overlays but as i recall it has zero uv protection and will yellow with age. ( casting resin that is )

#5

i added a bit more catalyst than i thought necessary, weather being cold and all, and one day later the thing was soft and sticky…i added another layer, just to see (hey if the part’s ruined, why not experiment?)…if the resin does not have wax additive, how sticky should it be? like gelcoat?

#6

The Silmar stuff I use also needs a very small amount of cat compared to other resins.
You can usually tell if there is wax in the liquid as it forms a kind of dull skin on top, or like you say, it sets like gelcoat. You will have difficulty sanding it with no wax additive - it just clogs up the sandpaper.

#7

Aga,

if you put 2% catalyst is not so matter. I use it in the past and now too. The only think is the geal coat cure more faster.

No problem.:wink:

#8

Speaking of clear polyester, is it ok to brush this on then do an infusion? Or will I be getting some “wavy” surfaces? Does this stuff self level well or can it be thinned to do so?

#9

First you put clear polyester with spray or brush or what ever and then you make the infusion with all other materials. If you make after the infusion then you will have “wavy” surface and too much work to make it shine.

#10

^^ Sorry, I think I may have made myself hard to understand or maybe its the other way around??? :smiley:

What Im trying to ask is that normally when you brush gelcoat into a mold you get these “wavy” brush stroke marks. What Im wondering is if I brushed in the clear gelcoat, would these mark show through after I do my infusion?

Not talking about any overlay here.

#11

Aaaaa ok,

Yes,I think 80% those mark shows will be through after you do your infusion.

It happen to me too. :frowning:

#12

So I guess the only way to do an infusion and get a nice finish is using a compressor and spraying? Is there no other way of doing it?? :frowning:

#13

Spraying is the proper way of applying poly and vinyl ester coatings.
Brushing will do OK at best, and is never ideal. For small parts, just spray several things at once.

#14

For small cups, I used a 3ml plastic eye dropper, my composite supplier sells them for about $0.50 each :slight_smile:

#15

some weeks later, and though the carbon is stuck to the surface (it was an overlay) , the fabric that is hanging out of the part is soft… maybe it was a casting resin?

#16

Improper cat. hardener to resin %.

But sometimes you can save it by heat / sun curing or adding another layer very HOT mixture.

#17

I found this today on ebay…

http://cgi.ebay.com/Clear-Resin-For-Carbon-Fiber-Fiberglass-Kevlar_W0QQitemZ120448947163QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1c0b5113db&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A3|39%3A1|293%3A2|294%3A100

If anyone needs any the same company sells it on their website.
www.compositeenvisions.com

#18

it was casting resin after all :rolleyes:

#19

i dont know how easy its where you are but a diabetic syringe is what i use to measure small amounts of catalyst. They are cheap and usually reusable 8 odd times before the rubber gets hard. Cost about 20c. I pull the top out first and dip it in catalyst this helps the rubber glide in the bore an makes it last longer before having to throw it out. Be careful not to wipe the outside where the graduation is printed as it will rub off once dipped.

#20

i just use a digital scale myself…