Teardrop Holes in Beaver 4.5?

[jrock22]

I feel bad constantly posting all these noob questions, so I appreciate how helpful ya'll are

Started pouring the beavers...had great success with my intended watermelon colors and initial black colors....but when I started pouring a recent black batch, stuff got weird. I can't isolate what I'm doing differently, but I'm now ending up with very small "holes" in the bait. I did the best I could to take a photo (see attached).

The recipe (which worked well with the watermelon green) is also attached. I do closely monitor temp with a thermometer.

Thoughts? Thx as always.

[ctom]

Its air coming from the pores in the sand cast aluminum. I'm thinking repeated injections could get rid of these pock marks, but you can also pick up a can of Hig Temp Engine enamel, black is fine. and spray the mating surfaces of the mold. Let it dry hard a couple days and then cast. The paint will seal the pores of the mold and the baits will have a much shinier appearance. Wash the mold good with alcohol or lacquer thinner and let dry an hour prior to painting.

[jrock22]

wow...interesting....ty!

[jrock22]

I notice in one of my senko molds the aluminum is a little rougher (and so that's reflected in the pour)...while the other mold is very very clean (and I get a much smoother senko pour)...I assume this could help that as well?

Any particular brand or will this to the trick?

https://www.amazon.com/VHT-SP145-Engine-Enamel-Gloss/dp/B000CPIMW6/ref=sr_1_2?crid=607PE3CO0TKL&keywords=vht+high+temp+engine+enamel&qid=1576863106&sprefix=high+temp+engine+enamel%2Caps%2C143&sr=8-2

[ctom]

That paint will work.

I know the bug mold is an essential mold. Are the senko molds both essential too?

[jrock22]

I have both...one senko es and one that's smooth aluminum.

[ctom]

The smooth one is a cnc cut mold and should not have any of the pock marks in a finished bait.

[WALLEYE WACKER]

https://www.youtube.com/watch?v=f3IZmISLEjY

Hope this helps in painting the mold

[bryanmc57]

I believe ctom meant to say spray the cavity of the mold, not the mating surfaces...   

Where did you get that recipe database?  It looks cool and I'm tired of having 100 pieces of paper laying around..  LOL

[ctom]

I second the where did you get the data sheet?

I've done the essential molds both ways - sprayed mating and taped and cut out cavities prior to spraying. Both worked equally well for me. I also used what it called liquid masking tape...a brush-on product that dries so it can be simply peeled off when the paint has dried. This stuff can be hard to find but is the cat's meow for prepping a mold for cavity painting.

[bryanmc57]

Where did you find the liquid masking tape?  That sounds like a neat product.  What do you gain by spraying the mating surfaces?

[ctom]

You save time spraying both mating surfaces. They're both equal unless a guy gets nuts with the paint. It takes very little paint to seal the sandcast. I can't recall where I go the liquid mas but it was a few years ago. I think a paint store...Sherwin Williams maybe.

[ctom]

JRock doesn't let us know where he's located. I'm in Minnesota and keep my molds in the furnace room of the house....on top of the boiler actually. They're hot from the get-go when I want to inject and I do that in a cool garage setting. This includes the Essential molds. A real warm mold will likely not get the dimples or pock marks as he describes because there's little heating of the mold required where air will be released in the micro pores of the aluminum causing the issues. If he's in a cold climate like I am and injecting the mold cold he may be able to eliminate the problem by simply pre-heating the mold.

I don't know how many cnc molds I have but hot or cold or in between I have never seen the small pock marks in baits from them. The Essential molds I have, if I inject the molds cold or un-sealed.

Cold and un-sealed sandcast molds can create vapor [moisture] when +325 degree plastic is shot into the cavities. Between the suddenly heated air and possibly water vapor from the resultant condensation created as cold and hot meet, these pock marks can occur. That's why I have sealed my Essential molds that may get winter use and have made the pock marks. I find that sealing them will work fine but I also know that keeping those sand cast mold really warm prior to injecting does away with the pock marks too. 

[MT204]

Someone clever needs to come up with an app. Take a picture and have the info listed. Maybe jrock has done this?

[BareKnuckleJigs]

Those bubbles are not from the texture of the sand cast.
That's marks left by bubbles that are getting trapped in the "scallops" in the cavity design.
CNC molds that have those details (and any other details that can trap air) will trap air in the exact same way.

Painting/coating the interior WILL NOT solve this issue.

Shoot that mold S-L-O-W.

Myself, I use the injector to fill the sprue and runner BEFORE putting the tip of the injector into the sprue.
Once the hot plastic is running out of the mold, WHILE STILL PUSHING PLASTIC OUT OF THE INJECTOR, ease the tip of the injector into the sprue and keep slowly filling the mold until it's full.
This way, there is no air held inside the sprue when the injector is in the sprue.
Slowly fill the mold.  Slowly.