Water Clear Polyester Casting Resin 1KG [inc. Catalyst, Syringe, Gloves]

Water Clear Polyester Casting Resin PY-WC-CR
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Product Description

Premium quality clear polyester casting resin suitable for clear sculpture casting, object embedding, jewellery making and set design. The resin is supplied complete with free MEKP catalyst, measuring syringe and nitrile gloves.

Water clear polyester casting resin is a cost effective alternative to more expensive clear polyurethane casting resins. Its low viscosity makes it suitable for reproducing incredible fine surface detail when casting sculptures and also ensures excellent wet-out when encapsulating/embedding objects in clear resin to make objects such as paperweights. The resin is very low reactivity meaning that quite thick sections can be cast in one go without distortion or discolouration and the natural UV stability of polyester means that finished parts will not fade or discolour even after prolonged exposure to sunlight which is great for outdoor pieces.

Water clear Polyester Casting Resin also has the advantage over polyurethane casting resin that it is less sensitive to moisture and so it is often possible to achieve better results with certain kinds of embedments using a polyester casting resin compared to a polyurethane casting resin, particularly those which naturally have a high moisture content such as organic matter. Although polyester is less sensitive to moisture it is still important to ensure that objects to be embedded are as dry as possible and some preparation is required to get the best results when working with certain types of material (see accompanying datasheet for further information).

Suggested Uses

  • Encapsulating / embedding objects (eg. paperweights)
  • Jewellery making
  • Water clear sculpture / artwork (glass-like castings)
  • Set design features (eg. ponds, lakes etc.)
  • Model-making / scenarios (eg. miniature lakes)
  • Stained glass effects*
  • Casting a semi translucent / tinted artwork*

*would require colour pigments

Pack Size and Contents

Our Water clear Polyester Casting Resin is available in 1KG, 5KG and 25KG packs; choose the pack-size you want from the drop-down list at the top of the page.

Also included in with all kit sizes is a measuring syringe, MEKP catalyst and nitrile gloves ensuring that you have everything you need to start casting right away.

Full Instructions

For full instructions on using the product, including hints and tips on artistic techniques and advice for embedding different types of object please download our Water clear Polyester Casting Resin Instructions Datasheet.

Translucent Tinting Pigments

Our Waterclear Polyurethane Casting Resin can easily be tinted with our range of Translucent Tinting Pigments to create stunning colour effects from subtle tints to vivid, vibrant colours.

Simply add a drop or less of these special pigments to your waterclear castings for amazing colour effects.

Colour tinting in this way can bring vivid life to lighting prototypes, jewellery and artwork.

Choosing the Right Resin System (Polyester or Polyurethane)

Easy Composites stock two types of water clear casting resin; this polyester casting resin and a polyurethane casting resin. Both resin systems can be used for similar projects so which one is right for you? Use this comparison table to identify the most suitable product for your needs:

Water clear Polyester Water clear Polyurethane
Price Low cost Higher Cost
Clarity Very good Excellent
Moisture Sensitivity Moderate Very Sensitive
UV Stability Excellent Excellent
Degassing Necessary? Not necessary Recommended
Air Contact Cured Finish Tacky Clean and clear
Reactivity Adjustable (by ratio) Fixed, fast reaction.
Pot-life (working time) 30mins 5mins
Cure time / de-mould 8-24hrs (depending on catalyst ratio) 1hr
Pigmentable? Yes, using polyester pigment paste Yes, using polyurethane pigment paste
Maximum casting thickness 75mm (per layer) 15mm (per layer)

Transport and Delivery Information

This product cannot be shipped outside of mainland United Kingdom. Customers from outside mainland UK should not purchse this product; it cannot be shipped internationally.

Click here for more information.

Technical Questions

Can I pour this resin over a polystyrene part?

No, our Waterclear Polyester Resin contains styrene which will dissolve polystyrene. If you need a water-clear resin that you can use directly onto polystyrene then we would recommend either our Waterclear Polyurethane Casting Resin or, if you need a clear resin but perfect clarity is not necessary then something like our EL2 Epoxy Laminating Resin could also work well and is a more cost-effective option.

Can I use an ordinary ice cream tub to hold the resin for embedding objects?

Probably. It depends what the icecream tub is made from. It's likely that it's made from polyethylene or polypropylene in which case the polyester should release from it naturally. I would suggest testing a small amount first to make sure it comes away easily with no adverse reaction.

Is it possible to add metal powders to this resin to create a metallic cast?

Yes, certainly; there's a few ways you can do this. You can dust metal powders into the mould first to add a slight metallic tint or you can mix the powders into the resin and then cast your piece. Following either process, you can enhance the metallic appearance by rubbing the cast piece with wire-wool to bring out the shine in the metal powders. You can also use polyester colour pigments in the resin, in combination with metal powders to make some very realistc metallic castings.

Can I use Uni-Mould based moulds with this resin for larger castings?

Yes, you can use Uni-Mould based moulds. However, you will need to use a mould release agent such as our Easy-Lease Chemical Release Agent to prevent the resin sticking to the mould. Also take care to ensure you do not pour layers deeper than 75mm in one go to prevent heat damage or discolouration.

When casting multiple layers, how visible is the boundary between the different layers?

Generally speaking you can only see the layer boundary when you look closely from particular angles. You will find there is a very slight refractive difference as the light passes through the boundary giving a boundary which is just about visible. In most cases it really is hard to spot.

I would like to embed metal items onto a table top using Waterclear Polyester Casting resin. How durable will the finished surface be?

For a primarily decorative piece with little use, this resin will produce good results, however it is not particularly scratch-resistant and so would be less suited for a table in regular use. Hot objects such as hot-drinks or plates would need to be avoided too. It’s important to note that any part of this resin that cures in contact with air will remain ‘tacky’ which means that if you pour a table-top, the open face will remain tacky. The easiest way to overcome this is to add some Solution MW Wax Additive to the resin (or if you’re doing multiple pours, to the resin on the last pour) which will allow the resin to cure hard on the surface. Other options are to sand and polish the tacky surface away or to pull a release film over the wet resin whilst it cures, preventing the surface from being in air contact.

Can I use this resin in vases as artificial water to hold the artificial flowers in place?

No, in most circumstances we would not recommend this resin as artificial water for flower arrangements. The reason is that if it’s a glass or ceramic vase then casting any rigid resin into it can be risky because the cast resin and the vase will expand and contract differently with variations in temperature. If you cast a rigid resin into a glass vase then it’s quite possible for the resin to expand a crack the vase. If you are using a glass vase then you would need to use a flexible clear casting resin which we don’t have in our range at the moment.

On the other hand, if it’s a plastic vase that you’re pouring into, such as acrylic or Perspex then it’s likely that a polyester casting resin like this would have an adverse reaction on the plastic of the vase and therefore should also be avoided. In this case, a clear epoxy casting resin should be used.

Can I use this to fill large natural holes within an oak board, whilst also embedding objects within the resin.

Yes this product would be suitable for this task. For best results add a little Solution MW Wax Gelcoat Additive to the resin to remove the surface tackiness associated with air curing of polyester resins. Once cured, you can simply sand smooth to be flush with the surrounding wood and polish the resin to a high gloss shine to show off the embedded items. Polishing would be best done using a range of increasingly fine abrasive papers and then polishing compound.

Can the Water Clear Polyester Casting Resin be used to coat a decorative table top?

In theory yes, Water Clear Polyester Casting Resin can be used in this way but polyesters have certain characteristics that you need to be aware of in order to make the best job of this. The main problem to overcome is to avoid ending up with the tacky surface normally associated with Polyester resins when it cures in contact with the air. We have found the best technique is to add around 1% of Solution MW Wax Additive to the resin. This will rise to top during curing and create a barrier between the resin and the air, ensuring that it cures without a tacky finish. What this will leave however is a slight ‘dithering’ on the surface which can either be left ‘as-is’ or polished to a full gloss using finer abrasive papers and polishing compound to ‘flat out’ the surface and polish it up to a full gloss.

I have used this resin to cast thin (2mm) window section. After curing, the surface remained tacky, how to I remove this?

Polyester casting resin will always remain tacky on the surface where it's been in contact with air. The best way to 'remove it' is to prevent it in the first place which would be acheived by placing some release-film or visqueen onto the surface of the resin whilst it cures. If you do this then you won't have the tacky surface.

Given that you do now have the tacky surface, the only thing to do would be to abrade it away and polish the surface. Rubbing gently on some abrasive paper, going up through the grits and finishing with a polishing compound would be the way to go.

Can I use this in a silicone mould?

Yes, certainly. Both of our types of silicone could be used but generally you'll get better results when casting water clear resins (polyurethane or polyester) by using an Addition Cure Silicone Rubber.

The resin does not seem to cure as quickly when I cast thinner amounts. I don't see how this can have an effect?

Thickness will certainly effect the cure speed of a casting. In a thicker casting, the resin gives off heat as it cures, as it gives off heat it cures faster which in turn causes it to give off more heat which then causes it to cure faster. This process is called exotherm. In a thinner section this process is much less pronounced (in fact hardly occurs at all) which is why thinner sections will cure much more slowly than thicker sections and so explains why higher catalyst ratios (up to 3%) are used for thin castings when low catalyst ratios (down to 0.5%) are used for much larger castings.

Ambient temperature (the room temperature you’re working in) also has a significant effect on the cure time; working in cooler conditions the resin will take much longer to cure compared to working in warmer conditions. For this reason, catalyst ratio can also be adjusted to compensate for warmer or colder conditions.

I have purchased the polyester resin to dip cast a sheep heart specimen, preserved in formalin and then washed off and put in phenoxetol. How do I dry this product and how long should I leave before using the resin?

I'm not 100% sure I know what you mean by 'dip casting', maybe you mean encapsulate/embed (i.e. pour resin all around) or perhaps you mean something more like coating the specimen so that it's not suspended in a resin but instead still has its original shape, just with a plastic sealed coating?

If you do mean to encapsulate/embed it then this might need some experimentation because organic specimens can be quite tricky to encapsulate without adverse reactions with the resin. I think I would suggest simply patting the specimen dry very thoroughly and then dipping it in some un-catalysed then removing it and leaving it over night. The next day you can proceed with encapsulating it by putting it in your mould and pouring the resin around it. Remember that experimentation first with organic specimens is very important.

What I should use to flat and polish the surface of the cured resin?

You should be able to flat and polish the cast polyester resin just like you would any other plastic which means that you can use abrasive papers and polishing compound to polish and buff it to a gloss finish.

What do I use as a material in which to embed an object before pouring resin into a mould?

There wouldn't normally be a different material that you would use to embed the object in first. Some objects (particularly organic matter) need some extra pre-work before encapsulating them, such as dipping them in resin the night before, but they should not need a different type of resin or material for this purpose. Please take a look at the technical datasheet for much more info on this type of preparation.

Can you use this resin to encapsulate a terminal block within a junction box? Will it be able to withstand water and outdoor conditions?

In theory, yes; you could use a clear polyester resin as a 'potting' resin however polyesters are rarely used for this purpose for a few reasons - the main one being that there are quite a few materials (plastics) which could be attacked by the styrene in the polyester resin meaning that you could find insulators or components on a PCB being affected by the resin. Another reason is that polyester resins are subject to more shrinkage than alternatives such as epoxy and polyurethane. For this reason, most electrical potting is done using epoxy resin; it has excellent resistance to water, is incredibly unlikely to have any adverse reaction with other materials and has a very low shrinkage. We don't sell an epoxy resin specifically as a casting/potting resin but our EL2 Epoxy Laminating Resin used with our SLOW hardener would by fine for small to medium sized electrical potting applications.

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