Updated: Jun 13
If you are new to floral casting, please also read my blog post with floral casting tips & suggestions for lots of important & helpful information on creating floral preservation art. It covers tips on drying flowers, why it's important to work in layers when working with organics, regardless of resin type or depth a resin can be poured in, and other tips. The preparation of your florals is a huge part of creating nice floral castings.
This blog post is specific to working with iCoat products in floral preservation art.
iCoat's Pro Tip: For very best and most consistent results, always use an infrared thermometer every time you work with epoxy.
iCoat CE4100 HV casting epoxy, is iCoat's most used epoxy for floral preservation casting in North America. You can use it on it's own through the whole mould, but some floral preservation artists also often use the HV (for base layer 1/4" to 3/8", and setting of flowers layer), then for the balance of the mould, another option often used is the iCoat Depth or iCoat TP21, both of which can be poured a bit deeper then the HV, to reduce the amount of times going back to add layers until full (although these other options do have longer cure times then the HV). You can also use the TP21 solely throughout the mould, and same for the Depth, as long as you remember to respect each products minimum pour suggestions in order to get best cure results.
To see info with photos, regarding creation of a floral preservation block piece created using the iCoat CE4100HV, click this blog post called, "Floral Casting 6x6x3", iCoat CE4100 HV".
iCoat CE4100 HV Casting Epoxy, is a 1:1 ratio, and a medium low viscosity epoxy resin. For ideal results, you will need to heat the bottles prior to using (see below) to make it more viscous which aids in reducing bubbles. This epoxy has a shore hardness rating at D63 at 14 days. This casting resin is not ideal for thinner depth (below 1/4") castings requiring harder cures (such as wine holders, rulers, bookmarks, coasters, etc., the iCoat Countertop resins & iCoat TP21, will work for those under 1/4" depth moulds). The minimum pour depth for HV casting epoxy, is about 1/4" up to a max of about 3/4"d with florals, (temp, volume, mass & mould dependent) per layer. HV Casting Epoxy cures in about 24 hours, (as with any epoxy, the lower depths will take longer, deeper depths will cure quicker). With the HV, you can typically pour about two layers per day. In a 6" x 6" x 3" mould, being used with florals, it is common to pour up to 6 layers to complete the 3" depth mould (to ensure you don't take chances with resin going thermic and overheating on you).
For best bubble free casting with iCoat HV, set bottles in a 5 gallon bucket with hot water, for about 15-20 minutes. At 10 minute mark, take lid off, and aim your infrared temperature gun down the bottle neck, to check what temperature the liquid is at. You want the liquid to be at the 82F temperature (no lower). If needed you can add more hot water until temperature is reached. Once temp is reached, thoroughly dry off containers before pouring liquid into measuring cup to mix. Any water drips that may fall from bottle in to cup, can ruin the cure. Please do not put both parts of the resin & hardener into your mix cup, then place the cup into water, as this adds moisture risks.
If you check with your IR temp gun, you will notice the epoxy once in the mould, will heat up to over 110F - 125F and possibly more during the curing process.
IMPORTANT NOTE: With this epoxy resin, use Infrared thermometer gun, to check previous layer of epoxy in mould. If epoxy in mould has returned to room temperature, you can add next layer.
iCoat TP21 Hard Cast Epoxy, is a 2:1 ratio, and low viscosity epoxy resin. TP21 epoxy does NOT require heating bottles to 82F prior to mixing to achieve crystal clear bubble free castings, however ideally, it should not be cold (cold is about 60F/15c range, warm is roughly 76F/24.5c), so if needed you can warm the bottles in a bucket of hot water. TP21 has a higher shore hardness rating of D78 at 14 day cure. The TP21 epoxy does take longer to cure, about 2 days to demould, (mass & volume dependent). Minimum pour depth is about 1/4" up to max of about 2"d, (temp volume, mass & mould dependent). When using with organics (florals) however, and you're newer with this type of resin & floral casting, it is safest to only pour roughly 3/4" per layer on 8x8" block style mould, or 7/8" on a 12x12" block style mould. The TP21 Casting Epoxy, cures in about 2 days, roughly 48 hours (as with any epoxy, lower depths will take longer, deeper depths with more mass will cure quicker). IMPORTANT NOTE: With this epoxy resin, use Infrared thermometer gun, to check previous layer of epoxy in mould. If it has returned to room temperature, and no longer sticky, you can add next layer.
iCoat Depth Epoxy is a 2:1 ratio, deep pouring epoxy resin, that is very low viscosity (thin like water). Depth epoxy does NOT require heating bottles to 82F prior to mixing to achieve crystal clear bubble free castings, however ideally, it should not be cold (Cold is rougly 60F/15C, warm is roughly 76F/24c), so if needed you can warm the bottles in a bucket of hot water. Shore hardness rating is D71 at 14 days. Minimum pour for the Depth is about 1" deep up to a maximum of 3-4" deep, (temp, volume, mass & mould dependent). When using with organics (florals) however, it is safest to only pour about 2"d layer on 8x8" block style mould, or 1 1/2"d on 12x12" block style mould. Demould with Depth is closer to 3 days (a bit longer than the TP21). Depth cures to touch in about 48-72 hours if poured at 2 1/2"d (when not using florals/organics). Thinner depth layers will have longer cure times based on environment conditions, temp, mass, mould, volume, etc.
IMPORTANT NOTE: With this epoxy resin, use Infrared thermometer gun, to check previous layer of epoxy in mould. If it has returned to room temperature, and no longer sticky, you can add next layer.
iCoat CT or MV Countertop epoxy resin.
While not necessary, some professional floral preservation artists, like to add a top flood coat layer using the iCoat Countertop or Medium Viscosity resin as a finish. It can also be used if there's any imperfections or dust on your finish. You would sand the top layer completely, Which also allows you to get nice edges, then clean it with isopropyl alcohol. Once dry, tape the sides, and be sure to burnish the tape tight to the piece, so no leaks can occur. Then pour the countertop resin over top, pushing the epoxy carefully up to the edges. With no mould to worry about scorching, the epoxy top coating can be torched free of bubbles. This will be dry by the next day. Be sure to remove the tape within 12 hours, so none gets trapped under hard cured resin.
For information on top-coating floral block pieces, please see the blog post Top-Coating /Flood-Coating Floral Pieces with iCoat.
Other example for using the iCoat CE4100 HV Casting Resin (1:1 ratio), for beginning layers to set flower arrangement, then once set, followed by the iCoat Depth Deep Pour casting resin (2:1 ratio) for balance of mould.
Example Using a 12”w x 12”h mould, you could pour about 3/8” base layer (for resin between florals & base) with the iCoat HV. With the iCoat HV, you can do your next layer in About 2 hours or so). So add florals, then pour about another 3/8” layer to help secure florals in place. Once this is set, you can fill balance of mould with the iCoat Depth. Or if you prefer to continue with only the HV, you can finish balance of mould, after you are past the florals section, in 1/2 to 3/4" or so layers,(depending on mass & volume, & mould size).
If you’re using the iCoat HV, ideally get resin warmed to temperature of about 82F. Warming bottles prior is best. But iCoat advises you can also use your heat gun on the resin in mix cups (the non melting cup type), after initial mixing, for short bursts between gentle stirring to get resin up to correct temp. (note: this process does not work with all casting resins, but does with all of iCoat's). You will see the resin go clear of bubbles. Then carefully & slowly pour resin in to mould, as close as possible to surface layer, to avoid adding bubbles during pour. Pop any bubbles as you see them. Let set.
Once it’s set, put flowers carefully in place. pour resin gently around & over florals. Once temperature of resin in mould returns to room temperature, flowers previously set in resin, should be secured, & you can then pour the iCoat Depth deep pour gently in about a 1 to 1.5” layer.
Note: The depth you pour will depend on the size of the mould, and amount of florals as well. Bigger molds and more florals/organics, may require you to pour shallower layers (regardless of depth epoxy is capable of), so that resin doesn't go thermic on you.
The deep pour epoxy stays in liquid state a long time, so it is less likely to overheat and burn florals, like some resins can in the 2 to 3” depth layers. Again, this is dependant on mass, mould, temperature, inclusions, etc. Practice and take notes for your mould size, and details you are using in your environment.
If you are pouring smaller ring holder style moulds, you can do your initial pour with HV to set the florals, then once they are set, you can fill the rest of the mould with HV to finish it, since it's not a large mould with a lot of mass, it won't overheat & burn the florals. Just be aware when working upside down the florals often float, so you may need to secure them in place with a layer, depending on floral type. If not using florals or anything that floats to the top, you can pour the smaller ring holder molds with one pour of any of the three iCoat Casting epoxies. The larger size ring holder moulds, would need to be done in more layers, or as some floral preservation artists do, you can switch to the Depth or TP21 depending on depth, for balance of mould.
For best results in perfect cures, keep room temperature consistently warm & over 75F throughout cure process. If room temperature cools, it can take longer to cure, and if it is not consistent temperature, it may not finish as nicely. Never move your moulds once cure process has started. Any changes during cure process, movement, inconsistent temperature in room, can cause a non smooth finish. Note: Even air blowing or movement around mould can cause a rippling effect in cure finish (watch there are no air conditioners, fans or heat vents near your curing area).
If that occurs, or you need to topcoat for another reason, you can add a thin 1/8” topcoat of iCoat Countertop or iCoat MV (medium viscosity countertop) resin (which will cure by next day). If using one of the iCoat countertop epoxies to do a clear topcoat, heat the Countertop bottles up to about 82F, (check with IR temp gun aimed inside neck of bottle). Because you are putting it on and spreading it out right away, the temp will drop quickly again. If you overheat epoxy by leaving it sit too long in mix cup, it will go thermic, which could cause dimples in finish. If only doing a topcoat, ideally remove the piece from the mould first, so the thicker topcoating resin can be torched to remove bubbles, without damaging mould.
Or, alternatively, you could add a layer of the iCoat HV casting resin, however if it's 1/4" you can use the HV, but be prepared to leave it cure longer. This will then take roughly a few days to cure before demoulding.