Alumilite clear resin not curing - advice please

[ChrisBcritter]

Has anyone had trouble with Alumilite clear resin not curing completely? I'm very careful to get an exact 50/50 mix; parts often come out soft and sticky. Is Part B the catalyst, and if so should I use a bit more? What's been your experience with it? Thanks as always for your help!

P.S. Room temp is mid-70s, humidity 35-40% if that helps.

[Ace-Garageguy]

In general you do NOT want to mess with the mix ratios of anything other than polyester...which this is not... and even then, we're talking about 1 percent + or - or so.

Six things are the most likely culprits when 2-component resin materials fail to cure properly.

1) Improper mix ratio

2) Incomplete mixing

3) Old material

4) Contamination. This can be moisture, or from mixing materials in waxed-paper cups, a greasy mixing stick, incompatible release agents, etc.

5) Section of casting too thin to cure fully. Some resins need to generate a little heat to kick off (exothermic reaction), and thin parts sometimes just don't go.

6) Low temperature. Most of these materials will work fine down to about 60F.

Your temperature and humidity are about perfect for working with this kind of stuff.

It may seem like overkill, but I ALWAYS mix everything (other than polyester) on a gram scale...and I never have curing problems if I do everything right.

NOTE: SOME resin products don't like SOME mold materials and SOME release agents, and incomplete cures can result. ALWAYS READ THE TECH MATERIAL FOR THE PRODUCTS YOU"RE USING TO DETERMINE COMPATIBILITY

Edited August 27, 2017 by Ace-Garageguy

[StevenGuthmiller]

Has anyone had trouble with Alumilite clear resin not curing completely? I'm very careful to get an exact 50/50 mix; parts often come out soft and sticky. Is Part B the catalyst, and if so should I use a bit more? What's been your experience with it? Thanks as always for your help!

P.S. Room temp is mid-70s, humidity 35-40% if that helps.

Had the exact same issue with Alumilite clear.

No matter what I tried, it never cured.

I gave up on it & started using Laser Bond glue instead.

 

Steve

[bill w]

I use Alumilite clear for all my clear parts and never had a problem. Everything Ace said is true, the mix ratio is 1:1 by weight. Clear resins as well as rubber resins

require a Platinum base RTV for proper curing, the Tin base RTV will inhibit the resin and it will not cure. Alumilite clear also requires heat for parts thinner than 1/8"

thick. I cast parts that are .065 to .075 thick and I always use pressure and 125 to 150 degrees F heat for four hours and let the mold cool for 10 hours.

 

Edited August 28, 2017 by bill w
spelling

[StevenGuthmiller]

I use Alumilite clear for all my clear parts and never had a problem. Everything Ace said is true, the mix ratio is 1:1 by weight. Clear resins as well as rubber resins

require a Platinum base RTV for proper curing, the Tin base RTV will inhibit the resin and it will not cure. Alumilite clear also requires heat for parts thinner than 1/8"

thick. I cast parts that are .065 to .075 thick and I always use pressure and 125 to 150 degrees F heat for four hours and let the mold cool for 10 hours.

 

Now I know I won't use it.

Way too complicated for me.

 

Steve

[ChrisBcritter]

Thanks to all for the advice! I've been using the Alumilite quick-set rubber for the molds - is that tin or platinum? Got a new mold poured for the '58 Ford taillights so maybe I'll take a shot at the Laser Bond first - I hear on this board that it doesn't turn amber like Bondic does?

Had one success with regular resin, anyway - cast a new set of whitewall inserts for the Aurora '34 Ford five-window coupe; I'm hoping vinyl tires won't melt resin like they do with styrene? I may be doing a lot of whitewall inserts if so!

[peteski]

Looks like Alumilite also sells UV-curable resin. https://www.alumilite.com/store/p/1027-Alumi-UV.aspx

Alumilite sells more than 1 type of clear resin. If you use Alumilite Water Clear then the tech specs state: that castings <1/8" will need a post-cure heating and that the molds shoudl be pre-heated to 125-150 deg. F.

 

As for which type of RTV you have (tin vs. platinum), that is described on https://www.alumilite.com/store/pg/47-Mold-Making-Alumilite-Mold-Making-Casting-Materials.aspx

 

Edited August 28, 2017 by peteski

[StevenGuthmiller]

Looks like Alumilite also sells UV-curable resin. https://www.alumilite.com/store/p/1027-Alumi-UV.asp

 

Now we're talking.

I say why mess with all of the trials of regular resin when you can zap it with UV light & have the part in hand & ready to use in seconds.

 

Steve

[peteski]

Now we're talking.

I say why mess with all of the trials of regular resin when you can zap it with UV light & have the part in hand & ready to use in seconds.

 

Steve

That resin seems fairly soft, but I suspect it is similar to all the As Seen on TV UV-curable glues. I'm also not certain if it is truly clear or slightly amber. One would probably have to contact Alumilite for a concrete answer.

 

The UV curable stuff is pretty much only good for open-mold and thin-cross-section castings. It is also fairly viscous. To me It has very limited application.

Edited August 29, 2017 by peteski

[StevenGuthmiller]

The UV curable stuff is pretty much only good for open-mold and thin-cross-section castings. It is also fairly viscous. To me It has very limited application.

Possibly.

But for the most part, I would assume that the most likely application for clear parts will be small parts like headlight, tail light, parking light lenses, etc.

At least that's all that I will need clear parts for.

 

Steve

[ChrisBcritter]

Plus four ounces of the stuff for $19.00 is a better deal than 4 grams of Bondic for $10.00.

Funny thing is, I was shopping at the Salvation Army thrift store a few weeks ago; spotted a UV nail-curing light for $12.00 and passed on it. Duh...

Edited August 29, 2017 by ChrisBcritter