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Alumilite FAQ

Alumilite FAQ

1st May 2021

Some of the most commonly asked questions (and answers) about Alumilite.

Q: Is Alumilite toxic?

Alumilite is non-toxic. First of all, we recommend you read any and all MSDS (Material Safety Data Sheets) and warning labels on any product that you use. All urethanes contain some type of Isocyanate. Alumilite have a very small, diluted amount of MDI Isocyanate, which was deregulated as hazardous and is not considered to be a hazardous material. Alumilite is not considered to be carcinogenic. Alumilite is safe to use in your home but is not recommended for children without adult supervision.

Q: What are the VOC and solid content of the Amazing Clear Cast? Does it have an odor?

Amazing Clear Cast contains no VOCs and it's a 100% solids. And has an average epoxy odor.

Q: What is the shelf life for Alumilite's casting resins?

1 year. However if the resin has been kept free from moisture, it may still be good to use for much longer periods of time. Resin as old as 4 and 5 years old work with no problems as long as it has been sealed and free from moisture.

Q: How do I avoid air bubbles?

Cast Alumilite into a warm mold coated with baby powder. This will help the material flow better and cure more evenly. 

If you are using silicone rubber moulds, stick the mold in an oven and warm gently at around 80C for 30 minutes, or put your mold in a microwave on high for 1 minute per lb of rubber. Once your mold is warm to the touch, sprinkle baby powder or talc powder in the mold. Shake the powder around the mold so all areas are covered. Once covered, knock or blow out all of the excess powder. This will leave a light coat of powder on the outside of the mold that will release the surface tension and allow the material to flow much better reducing the chance of trapping air bubbles. 

You can also use any kind of paint or commercial brand of urethane release. For complex molds that have severe undercuts, you may need to vent those troubled areas with holes that can be created with either some copper tubing or an Excel or Exacto knife.

Q: What is the best way to pour my part to eliminate air bubbles that are formed when casting?

If you are casting a part in an open or one piece mold, pour slowly from one corner of the mold and let the material flow naturally to fill the mold. If it is possible run the material down one side of the mold. If the mold has an undercut or complex corner you may pour the material to that point and then rotate your mold to evenly coat that area before topping off the mold. If you are pouring a closed or two piece mold, fill it completely until the material comes out of the vent hole and then tap the mold on the table to release any bubbles that may need a little assistance to get through the vent hole. You may also wish to rotate the mold and possibly squeeze the sides of the mold to assist hesitant bubbles in reaching the vent.

Q: Why is my clear resin white or cloudy?

A white swirl or cloudiness happens when the mix ratio becomes heavy with A side. Keep the mix ratio as close to 1:1 by weight as possible. It needs to be measured out by weight, not volume.

Q: How do you use Alumidust and Metallic powders?

There are three ways to use Alumidust.

(1) Brush it on you your silicone mold. It will bond to the Alumisol or any Alumilite casting resins.

(2) Mix it into your casting resin or Alumisol.

(3) Brush it on the surface of cooled soft plastic lures. You must then quickly pass a heat gun or torch over the surface to briefly remelt the surface of the Alumisol to lock in the Alumidust. Alumidust and Alumilite Metallic Powders are applied the same way. You can also mix colors to create custom colors.

Q: Can you vary ratios?

No. Varying the ratios will not affect the working time but it will affect the cure time and physical properties. Meaning, Alumilite will still start to set up in its normal time but could take hours to completely cure. When it finally does cure, it will not have the same properties of the regular resin and may be considerably weaker.

Q: How much heat does Alumilite generate?

This depends on the mass you are pouring, but typically ranges between 50°C (120°F) up to 95°C (200°F).

Q: Can Alumilite be coloured? What do I use?

Yes. Alumilite offers a full line of dyes specially formulated for Alumilites Casting Plastics.You can also use many other dyes/pigments, just make sure they are not water based. Some oil-based dyes are compatible. Test a small amount before mixing in larger quantities.  PearlEx and Caster's Choice Mica Powders are great with Alumilite's resin, and most powdered dyes will work as long they do not contain any moisture.

Q: Are all of Alumilite's resins UV Stable?

Alumilite opaque and clear resins (like all resins) will yellow over time if it is exposed to UV light. Clear acrylics or lacquers work well for protecting the resins from changing color. There are two ways of applying paint to achieve the best adhesion. First paint the mold and allow it to completely dry before casting your resin. As the resin flows into the painted mold, it will chemically bond to the paint as the resin is curing and after the resin cures you will demold a perfectly painted part. Painting the mold prior to casting allows you to reproduce perfect detail by painting becoming the outside layer of the actual part rather than cover the exact cast replica with paint that could then cover up fine detail. The other option for painting your part is to paint the part as soon as you remove the cast part from the mold and after you remove any flash while the resin is still curing. Although the resin is demoldable, the casting resin is still curing and if painted during the first 5 or 10 minutes of casting the part, the resin will still crosslink with the paint to give you not only a mechanical bond but also a chemical bond between the paint and the cast piece. Paints have built in UV stabilizers which then block out the UV light from ever reaching the casting resin which could affect the color.

Q: How long should I mix Alumilite?

Mix thoroughly for 20-30 seconds (be sure to scrape the sides and the bottom of your container). It should be mixed until absolutely no swirls or striations are visible. Try not to mix the resin in the graduated measuring cups because the raised letters and rigid inside prohibits you from scraping the sides effectively.

Q: Can I paint Alumilite?

Yes! We recommend lacquers or acrylics but you may also use synthetics or enamels. A lacquer primer may be needed to assure the long term effectiveness of the paint. You may wish to paint your silicone mold before casting Alumilite. Paint the mold with a fast drying acrylic or clear coat. Once it is completely dry, cast your piece. When you demold the part you will pull out a painted piece. Alumilite will chemically bond to the dried paint. The other option is to paint the part as soon as it comes out of the mold while the resin is still curing to allow the curing resin to crosslink with the paint.

Q: Why is my Alumilite Casting resin foaming?

Moisture contamination in urethanes causes foaming. If it foams quite a bit, most likely the moisture is right in the Alumilite. The moisture is usually in the A-side. There is not a full proof method of removing moisture from your system. Typically the B side will crystallize when moisture is present. The A side, however, will not look any different. You can try to use a molecular sieve in the A side. Mix the sieve into the resin and allow to settle to the bottom for a couple days. Then test the resin to see if the sieve was effective in removing the air. You can also try to vacuum the A-side to relieve it of moisture. Vacuum the A side for 20-30 minutes until it completely stops bubbling. If you dont have access to vacuuming equipment or a molecular sieve, the last chance would be to boil the moisture off. This is possible because water has a lower boiling temperature than any of the other liquids in the A-side. To boil off the material, we recommend that you put the Alumilite resin in a glass or metal container and place the material in an oven at 250°F for 2 hours. This will draw the moisture out of the system and evaporate it. If you are getting a bunch of little pinholes, the moisture is probably coming from some materials you are using (mold, cups, stir sticks, filler, etc.).

Q: My part is very hard to get out of my one piece silicone mold. Is there anything I can do to help it release easier?

Yes! To aid in the release of silicone rubber from your mold box or your original, use a small amount of rubbing alcohol. The rubbing alcohol will make the cured silicone very slippery and will help seperate the silicone from the other surface. After you remove the original, dry out the excess alcohol with a paper towel or dry cloth. Be sure to warm and dry out the mold COMPLETELY before pouring resin into the mold to avoid the alcohol from contaminating and affecting the resin. You can also use rubbing alcohol to assist you in removing resin pieces out of a silicone rubber mold. Use the same process as mentioned above for removing your mold from the original and the mold box. Make sure the resin is cured before putting the alcohol in the mold.

Q: How do I determine if I need a mold release?

The rule of thumb is this; silicone bonds to nothing but another silicone, Alumilite (urethane) bonds to everything but silicone! When pouring RTV silicone against any non silicone surface (exception: a porous surface, such as wood, it would need to be sealed, silicone can wick into the pours while curing), mold release is not required. If you are pouring RTV silicone against itself a rubber to rubber mold release is REQUIRED! If you are pouring Alumilite into anything but silicone, a mold release is REQUIRED. The Stoner Urethane Mold Release works very well for non silicone based molds.

Q: If I short pour a mold, can I add more? Does Alumilite bond to itself well?

Bonding Alumilite to itself is best when the material is still curing or while it it is still warm. If the Alumilite has cooled down, make sure you have a clean surface and lightly score or/sand in order to give it some bite for better adhesion.

Q: It has been 4 hours and my clear resin is still flexible, will it harden?

A post heat cure is strongly recommended for all clear pieces, but less than 1/8" must be post cured. Post curing the clear on the lowest setting on the conventional oven typically 140-160 F. for an hour or two (parts may require some support during heat curing) will minimize part distortion and shrinkage, while giving maximum toughness. It is also highly recommended to preheat molds to 125F. prior to pouring your resin in the mold.

Q: Is the Amazing Clear Cast UV stable?

Amazing Clear Cast will begin to yellow over time and with UV exposure, therefore is not recommended for outdoor applications. The big advantage of it lies in the viscosity and cure time which allows you to coat large items such as bar tops as well as gives the air time to release out of the material before curing which in some cases can eliminate the need for degassing some parts that would otherwise require it.

Q: I'm using Alumilite Clear in an open box, and I've run into 2 problems: The resin climbs the sides of the box (capillary action), and the surface of the resin is not flat. Any tips on how to get a completely flat surface on the back?

What I like to do is get a piece of glass or thick clear plastic, mold release it!! I like the Stoner release for this application, as I think the UMR hazes the surface a little more than the Stoner. Only use a little to reduce witness marks for the release but make sure you have enough to release it. You would then over pour the cavity, and use the glass to slowly squish the excess material (from one side to the other) to create perfectly flat back. You do not want to squish the glass past flat. We only want to lay it on the back side until it is flat. If you force the plate too far down, when the mold retracts it will suck in air. So lay the glass on from one side to the other in a slow smooth motion and place an adequate amount of weight on top to hold it in place until it cures.

Q: I have some dried crystals in my Casting Resin in the bottom of the bottle is it useable?

Mild agitation by rotation of the unopended bottle will dislodged it but it returns after only a few minutes of standing. The best way to get rid of it permanently is to strain the chunks out. You can also simply not pour them into the measuring cup and it will work fine. Sediment in the Iso side (B side) is simply moisture that has reacted with it and fallen to the bottom.

Q: Are any Alumilite casting resins food safe?

The Amazing Clear Cast comply with FDA CFR 177.2600. Please note - the resin is FDA compliant only if it is measured 1:1 by volume exactly, and it is completely blended/mixed so all chemicals cross link becoming inert. It then needs to be left for a complete 7 day full cure schedule before using, and then washed with warm, NOT hot mild soap and water.

It is NOT recommended for hot food or drink, no dishwasher, no microwave. It is not recommended for outdoor use in high heat.

Amazing Clear Cast is the ONLY food safe Alumilite resin.

Q: What is the maximum heat temperature that Amazing Clear Cast can take? Will it melt at some point?

What prolonged exposure to high heat will do is soften the resin, whereas you could take your fingernail and make an indentation in the coating. Although, it's also very important that the resin be mixed accurately and cured fully. We've found that some users are mixing such small amounts that they do not realize that they are going off ratio. Mixing off ratio could cause the product not to cure fully or cure to cured specification. If users are mixing less than 1 fl. oz., we recommend mixing 1:1 by weight. Overall, we recommend avoiding prolonged exposure to temperatures beyond 130F.

Q: What is durometer and viscosity, along with other terminology that will help me understand, what I am looking for, what I need and what I am getting?

Viscosity...Viscosity tells you how thick or thin a liquid is. The higher the viscosity number the thicker the liquid. 

Durometer refers to hardness ... How hard or how soft a material is. Shore 'D' durometer refers to hard materials and surfaces such as the rigid resins. Softer materials are rated on the Shore 'A' scale. The higher the number, the harder it is. How easy it is to flex a rubber or the flexible urethanes it is decided by both the hardness and the thickness as soft flexible materials feel harder as the part thickness increases. 

Tensile Strength... is measured by grabbing two ends and pulling them apart until the part breaks. This measures the tensile strength and also gives you an idea of how elongation by measuring how much it stretches before breaking as well. 

Pot Life... Amount of time you have after two components have been mixed together before your chemical reaction starts to occur and your compounds will begin to set. 

Demold Time... The time you have to wait after it is solid enough to remove from your mold box or piece from your mold. At the demold time, it is solidified enough to handle but has not reached a full homogenous cure or it's full strength. 

Cure Time... Your materials has reached "full strength and cure" 

Fillers... Materials used to manipulate the resin to achieve a specific look, appearance, or function. There are many materials that act as fillers such as sand, aluminum powder, granite, calcium carbonate, microballoons, porcelain powders, etc. The percentage of filler recommended depends on the purpose and requirements of the finished piece. Typically 50-100% by volume is added to achieve the desired effect and not thicken the material so much that you are unable to mix and pour the material effectively.