Epoxy tooling surface coat anomoly?

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#1

Ok so I am testing an epoxy tooling surface coat and I had a weird thing happen. Once it was all mixed up(very well mixed with no bubbles and weighed on a scale) I proceeded to pour on the surface coat onto the very smooth plug. I levelled it all out and everything in the lay up went like normal.

But once I removed the cured mold off the plug there were these strange swirl marks on the mold surface of the epoxy coat, kind of like swirl makes left over from where the surface coat was poured onto the plug everywhere. It’s not bubbles but just a bit textured looking… anyone know what this is?

#2

got a photo?

#3

Here are the best I could get them.

#4

well, it doesnt look like it affects the surface … right?

#5

I get the same thing on the epoxy surface coats I applied. I can always see where I poured the surface coat on to the mold. I think it is just the way the fillers are in them. It looks like you have some surface purosity, make sure you mix your surface well in one cup then transfer to a second cup and mix, then degass to remove any remaining air, this will help keep your surface purosity down.

#6

Thanks good tips! Will that pervernt the pouring pattern or just the porosity?

How long are you degassing for? How long is the pot life of the stuff you work with? The one I have is about 18min…

#7

it does affect the surface, it leaves it a little bit rough where it happens, these pics are after light sanding and some polishing, I didn’t hink to take pics before I got my hands dirty… hojo hit it right on with what it is.

#8

about resin, the one i use has 40 minutes pot time, but in about 5 minutes , it has degassed… its up to the resin, in some resins the bubbles dont move towards the surface as much… you can always build a vacuum chamber, its not hard…

#9

I always use huntsman 8026 epoxy surface coat, and I usually degass it for atleast 5 minutes. huntsman has atleast 3 different speed hardeners for that, I have used slow and medium, medium is about 45 minutes, and slow is about 60-75 minutes gel time. personally I always like to use the slowest speed hardener because I like to have some gravy space and dont like being rushed. if you dont want the swirl marks dont pour the stuff on, put the surface coat on to something flat and use a squeegie to apply it.

#10

i will give the squeege technique a try. Are you able to sand then buff the marks out? Mine came out ok. My resin is Al filled and very thick non sagging

#11

they usually sand out, the 8026 is also aluminum filled

#12

i dont know about the brands you guys use, but i also used an epoxy mold resin last weekend and the stuff was damn thick, like automotive sealer. however, the instructions however said to use a brush…

#13

I never liked using a brush because it is too thick and is hard to control thickness. I always have found that a squeegie works best