Making a Durable Aluminum Pattern For Casting Plaques

And why did you paint the embossments?

Was there some filling pores involved and you wanted to hide the filer material?

Yeah I'm going somewhere with this but await your answer first so I do stick my foot in my mouth.

 

Just a quick one, what grade sand paper did you use to get the shine on your numbers?

 

First off, any time you plan on painting aluminummmmmm, it needs to have a base coat of zinc chromate or phosphate applied.
If you go and look up the application parameters for the phosphate it's going to tell ya it's only for steel. Wrong, it works on aluminum as well.

Once it's applied and the correct amount of flash time has elapsed you can apply your top coat.

In reference to the embossed areas.
If finances are an issue the caster can take a bar of soap and coat the areas they wish not to end up painted one finished.
The soap will not only provide a barrier but fill all those pits in and keep the paint out.
After it's painted and sanded you can easily scrub the remaining soup out of the pits.

In reality, you could also apply some crystal clear resin to the embossments as well prior to painting since the embossments are gonna end up getting sanded anyways.
You would have to apply multiple coats though to build up the bottom of the pits to become level with the original highest surface point.

The is latex rubber masking on the market that can be applied to areas one wants to protect from becoming painted as well.

Years ago I ran a paint department for a LARGE sign manufacturing corporation and used a product called Spraylat.
It's a latex base masking used on all kinds of signage and illuminated acrylic faces and the like.

There's other product out there called Sign Stripe which does the same thing.

Here's one ink just to show you what it is.

https://www.coastairbrush.com/proddetail.asp?prod=Spray_Mask_by_Spraylat&cat=331

Shop around for pricing.

You brush or spray it on, let it cure, (usually over night or 8 hours depending on mil thickness) cut around the outlines or area to be kept masked off with an exacta knife, peel away excessive masking or areas to be painted.
Once product is painted, peel of remaining masking.

Or you could stop pouring aluminum Kelly sent you. No more holes.

Just ribbing ya Kelly.

Seriously, go by a darn replacement belt for your sander.

A regular ole electric orbital hand sander would resurface those embossments down with the correct sandpaper.
Would take awhile but it can be done.

Went prepping aluminum surfaces after a casting, 150, 220, 320, 400, 600 and polish out with some mag polishing cream.

There's all kinds of clear metal protector sealants out there to seal your metal projects with.
Just make sure the top sealant coat has the same solvent content as the base coat. (E.g., water based, solvent based, etc.)

If you spray a solvent based sealer over a latex based paint it'll gator it and cause crinkles/wrinkles.
You can spray or apply oil over water but can't apply water over oil.


There so many different ways and products you can utilize to apply to you projects to result in a quality finish.

 

Really great job that!

 

That looks first class.

 

Nice Green Color! (Makes me want Green Transtint dye...) Good casting!

 

Nice thread Jeff! I am working on something similar now but am going to add a bell for delivery people. Tired of finding my packages hidden in random locations. I drove around with a trampoline in the back of my truck for a day or two because I didnt know it was there. LOL

 

You can make changes to the gating on the cast pattern pretty easy. I saw the streaks on the first casting and figured that was where you had packed the sand harder and left some vents out. What other defects are you having issues with?

 

I will give you a couple of options to try and give broad advice. You can see some of those for yourself if they are consistent in all your thinner castings. High moisture in sand...low permeability of the sand...low pouring temps...volatile combustible in sand. I'm sure some are eluding me but I'm playing Peppa Pig with the boss so please forgive me if I add later..on just this pattern scenarios...pour faster...pour hotter...add more vents...dont worry so much about trapping oxides and try to make everything more of a smooth transition as I promise you sand wash is way more of a source of inclusions than oxides if you do a good job of cleaning your metal and try to pour without any interruptions. Reducing your runner will increase your velocity and make it pour faster and help get the streak out but will increase the risk of washing sand so make sure your mold is clean and hard around ingate area. Getting yelled at gotta bail.

 

That's an interesting observation. I understood that was from wandering metal fronts stopping and restarting, etc. I'm pretty sure that's what it has been in at least some instances because the "streak" frequently goes through the whole cross section of the casting to the other side, but maybe I've been misunderstanding the issue. Maybe we could explore this a little more?